FM Transmitters

[ThelegacyParticipant Total posts : 148]

Earlier on another thread there was mention of so many different transmitter manufacturers that I decided to start a new thread just for Transmitters so we can get this thing going. Please tell us rather or not the Transmitter has a certification and if so the FCC ID# if possible. Here is a start.

 

SainSonic AX-05B http://www.sainsonic.com/sainsonic-0-5w-long-range-10km-dual-mode-stereo-broadcast-fm-radio-transmitter-fashion-black.html

 

FCC Part 15 compliant FCC ID # 2ABT5AX05B7C Low Power -48dbM/500 mW (To adjust power hold down the power button while unit is unplugged then plug power in. Press Down arrow to switch to -48dbM or up arrow for 500mW Click power to confirm. You’ll see the highest frequency 108Mhz click to confirm. Then you’ll see lowest frequency 88.1 Mhz click power to confirm. Click again and transmitter will say OFF and the desplay will be dark. Now press power and select a blank frequency.

 

FM Stereo IC with PLL technology 75uS Audio pre emphasis, Limiter and Low Pass filter circuit. Large Digital display with blue backlight. Aluminum Enclosure. 88.1-107.9 Mhz US Factory setting or 76-108 Mhz outside USA. Tuning step 100Khz/0.1 Mhz. Power Supply 9-12 Volt DC (the current load of power supply should over 1A). Stability of frequency +- 0ppm (-10C +50C). Frequency Response 100-15000 Hz. Frequency to noise ratio >70db. Distortion <o.5%. Operation Time: True 24.7. Antenna Design: Rubber Antenna. Output Impedance 50 Ohm. Audio Input Connector: 3.5 mm headphone connector. Mic Input Connector: 3.5 mm headphone connector. Size of transmitter 113*88*38 mm. Transmission Signal: Stereo. Barrier free broadcast on 500mW setting 1,300 Feet (gray area in USA Note: I put that one in).

 

All specs were from the actually box the transmitter came in. Website says low power is 100mW but the actual transmitter when it arrived and I opened the package says low power is -48dbM (far less than 100mW). Again this is the revised transmitter with reverse threaded TNC connector.

 

[Carl Blare Total posts : 0]

On my website’s Part 15 page I have a column of transmitters where much information can be found.

http://kdxradio.com/am.html

Also, the ALPB has started a growing collection of transmitter manuals and data sheets thanks to Jeff Station8.

http://thealpb.com/equip-info.htm

Undefaced by water marks.

[MICRO1700 Total posts : 0]

I want to do some reading myself about

the transmitter mentioned above by Mr. Legacy.

What is -48 dbm in milliwatts or fractions of milliwatts?

I should know how to convert but I forgot and don’t

have the references.

Thank you for starting this thread.

Very best wishes

Brooce, DOGRADIO etc.

[ArtisanRadio Total posts : 0]

Here are some other FM transmitters that I’ve used.

The Decade MS-100.  Excellent quality, built well, probably can be considered the cadillac of all the certified FM transmitters.  Both Industry Canada (RSS210) and FCC certified. Transmitters shipped within Canada can be tuned for the BETS standard of 1000uv/m at 3 meters.  I believe the list price is around $700 for a mono one but you can buy for less.  Sometimes they show up used on e-bay for a fraction of the new price.

Landmark FM-350.  Both Industry Canada (RSS210) and FCC certified.  Good quality, good sound, built-in power supply and industrial grade CD player.  Can operate in either stereo or mono.  Discontinued & hard to find (if not nearly impossible).

Broadcast Vision made a series of FM transmitters targeted at gyms and other such establishments.  FCC certified.  Reasonable quality and sound, stereo only.  I don’t know if they’re still made or not. Can sometimes be found used on e-bay for around $100.

Panaxis ACC-100.  Mono or stereo FCC certified transmitter.  OK quality and sound.  I had problems with hum on mine until I threw away the supplied wall wart and replaced it with a much better one.  Discontinued but you can occasionally find them used on e-bay, sometimes for $50 or less.

I’ve put them in order of my preference.  Unfortunately, only the Decade is still made.  I still own one Decade (mono) and the Landmark.

[station8 Total posts : 0]

Hi ArtisanRadio: Here is information on the Panaxis ACC-100.  Mono or stereo FCC certified transmitter,Discontinued but you can occasionally find them used on e-bay, sometimes for $50 or less.

Let me corrected you on the panaxis acc-100 fm transmitter & stereo generator.

I found out  while working on a panaxis manuals that panaxis company was bought by progressive concept back in 1990 and they own the copyrights.

I have talked to the president of progissive concept to comfrim this and he has given the alpb written premission to put some of panaxis manuals on our web site.

Progressive concept will NOT allow use to put the panaxis acc-100 fm tx and the fm stereo generator manuas up do to they still make both of these products and you can purchase from progessive concept.

So if you would like to purchase the panaxis ACC-100 fm tx and the fm stereo generator please contact progressive concept.

 http://www.progressive-concepts.com/

Can find it under part 15 fm transmitter

I hope this clears some items up

station 8

 

 

[ArtisanRadio Total posts : 0]

Thanks for the updated info.  I wasn’t aware that they were still made.  Bet you they’re a lot more than $50 new, though.

[Carl Blare Total posts : 0]

One transmitter I haven’t noticed mentioned is the EDM.

Brooce MICRO 1690/1700 Dog Radio Studio 2 WIFE 750 tells us that the EDM is an excellent and highly rated transmitter.

I got a link so we can see it:

http://www.edmdesign.com/

[MICRO1700 Total posts : 0]

About the EDM – I have had no personal

experience with it and I’m 99 percent sure

it’s not certified.  I have just heard tons of

good things about it.  I would rather have

a certified transmitter.

I’ll probably listen to your station tonight.

Especially overnight when you are running

the (creative commons) book reading shows.

It will go out from my Maxell at 88.3.  As

we know – the Maxell covers the house great –

but I would have to put it outside for anyone

else to hear it – so it will just be me listening.

Me and the dogs.

Bruce, DOGRADIO

[wdcx Total posts : 0]

Broadcast Vision still around.

[MrBruce Total posts : 0]

So far so good, keep the information coming in.

Bruce.

[Carl Blare Total posts : 0]

The EDM appears to be something of a kit, so I guess it couldn’t be certified. But it sure looks interesting.

Right, tonight on “Radio Books” we will hear a reading of “The World Set Free” by H.G.Wells.

Maybe someday we’ll read about “Part 15 Set Free.” The watchful jail guards will be out of a job.

Got to go now, busy evading things.

[ArtisanRadio Total posts : 0]

I had an EDM and played around with it a bit.  Mixed feelings about it.

First, it’s way too powerful, even for Canada.  When my Decade was fading out, the EDM was still strong.  You might be able to create a mismatch on the antenna to reduce the field strength sufficently for Canada.  But I don’t know what that would do to the output transistor if you used it for any extended period of time.

It’s really, really sensitive to hum from the power supply (there’s no on board filtering, at least in the one I had).  You have to use a well regulated power supply.  Luckily I had my amateur radio supply; I even had issues with regulated wall warts (I guess they weren’t regulated enough).

If you can eliminate hum, it sounds really good.  But I did notice that it did bleed onto adjacent FM channels more than other transmitters, even at a distance.  When I’m running the Decade at, say, 103.9, I can tune my car radio to 103.7, or 104.1 and hear another station there (weak, but they’re there).  With the EDM, at the same distance, those stations are obliterated.

Even ignoring the fact that using one wouldn’t be legal, I think that there are better alternatives (albeit more expensive, but you do get what you pay for).

[Thelegacy Total posts : 0]

I’ve read about some of those issues.  Funny that the SainSonic costs far less and you don’t get that sort of issue unless your right on top of it and that is only at high power.  Its the fault of the EDM transmitter from what I see.

[Carl Blare Total posts : 0]

Another undocumented discovery, by simply adding a length of wire to the C.Crane certified FM transmitter it is possible to match BETS field strength.

Of course there is no way I could know this on my own without exceeding 15.239 which would bring the Rulebook Thumbers and Stone Throwers, so I had it independantly checked by an anonymous individual at an undisclosed location.

[Thelegacy Total posts : 0]

There is also the variable pot I assume is for BETS but it would have to be compared with the Decade.  How is the harmonic and spur issues?  Does the C.crane wipe out the dial on high power like the Whole House FM transmitter 3.0?

[MrBruce Total posts : 0]

I suppose it wouldn’t hurt for everyone to add a band pass filter into the transmitter to help prevent out of band spurs and harmonics.

Ramsey has a filter kit that can also be bought already assembled that can be placed inside the transmitter cabinet just before the output stage goes to the stock antenna or rubber ducky.

Has anyone tried this on these various certified FM transmitters?

Has anyone tried this on FM transmitters kits?

If so, please share your way of using this filter, whether it was internally installed or externally installed in the transmitter’s antenna feed line.

Did it clean up any issues with out of band interference or spurs?

If there is proof this filter or ones like it actually work, perhaps we should all install one in our FM transmitters to go that extra mile to prevent unwanted interference.

http://www.ramseyelectronics.com/FM-Low-Pass-Filter-Kit/dp/B0002NRJQS

Bruce.

[MICRO1700 Total posts : 0]

I have had many FM transmitters over the years.

Right now, I only have a few Part 15 FMs here.  Some of

my other FM transmitters are in other locations.

Anyway – I use the

Maxell P-13 (certified) to run the computer audio

out to radios that are here.  Lately, it’s been 

streaming stations of most of you guys.  The Maxell

is an odd beast.  A little round thing that just plugs

into the computer.  3 AAAs, a blue power-on LED, and

just 4 channels, as mentioned before.  88.1, 88.3, 88.5,

and 88.7.  Not easy for me, or anybody – I figure – with

just those 4 channels.  Also, it only does about 80 percent

modulation – and the EQ is wrong.

Still for an audio link – man – you can’t beat it.  Just

put it in your pocket and go wherever you want.

You can lose it in your pocket.

The P-13 came after the Maxell FMT-1.  The FMT-1

had a red power LED, and a very small antenna wire

in the battery compartment.  I’ve never seen an FMT-1,

but I think the wire  could hang out the bottom of that 

transmitter.  So when Maxell went from the FMT-1 to the

P-13 (why do they call it a P-13) they changed the color

of the LED, and got rid of the little antenna wire.  Otherwise,

all is the same.

I’m very happy with my Maxell P-13.  It is what it is.

OOOps.  The batteries ran down again.  Back to the

charger.

The only other transmitter I have here is a Whole House

1.0 circuit board that came from E-bay for about 9 dollars.

It seems to be the right field strength, but if you put the

transmitting antenna next to the board you get RF feedback.

Other than that it appears to be clean RF wise, but I don’t

use it much.  It needs to go into a shielded case, and needs

some other things to make it practical.

Now to my real question  – the Sainsonic FM transmitter.  That

sure looks like an FCC certification number.  The Sainsonic can

do 500 miliwatts and can go out of band down to 76 MHz.

However, as we know, the Whole House FM transmitter can

do the BETS field strength.  Also one of our members has 

an FCC certified Part 15 transmitter that can also do 87.5,

87.7, and 87.9.  (I forgot the manufacturer and model number,

but if you told me it- I’d hit myself over the head and say, 

“Oh – right!”)

I’ve heard that some of the clones of the Sainsonic had

problems with unwanted RF products outside the desired

operating channel.  Several manufacturers seen to market

this thing – they all look the same – but are under different

names.  So the Sainsonic is the only one out of the bunch

that passed certification?  Was it a mistake?  Back many

years ago, the FCC certified some kind of AM “Real Estate”

transmitter that was too strong.  I want to know more about

the Sainsonic.  I need something with more than 4 channels,

and is in a good strong enclosure, and is NEW.  Mono would be

great, but I don’t know if the Sainsonic does mono.  In the

$54.00 price range, this is less expensive than many other

Part 15 certified FM transmitters that we KNOW AND TRUST on

a technical level.  But is the Sainsonic really any good??? 

Does anybody with the ability to see if it is “clean RF wise” have one?

Is the certification a mistake?

If I was rich I would just get one to check.

Best Wishes,

Brooce, DOGRADIO

 

[Thelegacy Total posts : 0]

The SainSonic is 100% Clean. I know this because I had to call an ambulance because of someone who had a heat stroke working outside my house. I forgot to turn off the transmitter and the cops and paramedics were in the room right outside of where I transmit. No interference was caused but I quickly remembered Oh crap gotta turn off the transmitter. If I would have caused interference I would have gotten arrested right johnny on the spot by the police here as they don’t play here in this town. And as reported the SainSonic is even cleaner than the $125 Whole House FM Transmitter 3.0. Out of the box it is set to 88.1-108 Mhz and the wattage to -48dbm and can be set to the 500mW setting and can be reset to go to 87.9 Mhz but here in the USA that is a gray area. Even at the high power level the RF beats the Whole House FM Transmitter all over the place. Though it comes from China SainSonic made sure that they modified this transmitter to the specs SainSonic wanted. The FailSafe, Sinstec, and all the others are knock off copies and are not the same thing as the SainSonic. The SainSonic is aluminum and made extremely durable. I run mine all the time and is the best Transmitter I ever owned even better than the one I had years ago. I’d never IMHO buy the Whole House FM Transmitter 3.0 after I heard so much about spurs and harmonics something the SainSonic does not do yes even at High Power it causes less Interference to the FM band 10 foot away than the Whole House FM Transmitter 3.0. More money doesn’t necessarily mean better in this case. I’ve research this for more than a year before I bought the SainSonic and darn glad I saved $100 and bought this one.

[wdcx Total posts : 0]

Audio-wise, I think the knock on this uncertified transmitter is that it is 50 uSec rather than 75 uSec.

 

[ArtisanRadio Total posts : 0]

Brooce, the Sainsonic really is certified.  The entire purpose of certification is to allow them to sell the transmitter they got certified in the U.S.  That number does exist in the FCC database (or at least it did a little while ago).

Whether the Sainsonic that is being shipped from China really is the same one that was certified is unknown (in my opinion).  The existence of a ‘high power’ switch obviously doesn’t matter to certification, as the Whole House 2 & 3 has those (and the original C-Crane had a hidden power adjustment), and they are/were certified and sold in North America.  The fact that Sainsonic is advertising up to 1/4 mile range is suspect, as there’s no way without an elaborate receiving system, including an outside directional antenna, that you could receive a legal Part 15 signal that distance (and even then, I’m not sure).  However, that could just be the marketing hype.  The transmitter box as shipped does have the certification number on it (according to theLegacy), so anyone purchasing it certainly can’t be accused of attempting to circumvent the rules.

It would be interesting to measure the field strength of the stock, out of the box Sainsonic.

[ArtisanRadio Total posts : 0]

John, are you talking about the Sainsonic?  If so, do you know that the pre-emphasis is is 50 as a fact? 

[wdcx Total posts : 0]

There are no applications on file that match the search criteria specified: 
Grantee Code: 2ABT5 Product Code: AX05B7C

To Artisan, Yes they are 50 uSec

[MICRO1700 Total posts : 0]

very much.

Great into from everyone – this will help me to

figure out what FM transmitter to get next.

Bruce, DOGRADIO

[Thelegacy Total posts : 0]

It is 75uS not 50 uS ans I both called and Emailed SainSonic to make shot gun sure it was 75uS.  This was a mod SainSonic had the Chinese do to the transmitter to meet their specs.  James told me many folks wanted to have the 75 uS pre emphasis so this transmitter has it.  I bought it just before June 5th and it was shipped to my Studio’s here at The Legacy and I can tell you it came certified.  So this transmitter is the real deal.  Audio quality meets the Album Rock standard and I’m picky about audio.  The volume will be a little less than a commercial licensed station. Here is how to set it up using NextKast.

 

1. Purchase a separate sound card.  I got mine on Amazon for $16.  Set the volume of the separate sound card to 35%.

2.  Set NextKast’s second sound card to your new sound card.

3.  Set the Audio volume on the SainSonic AX-05B to point to where the two halves of the transmitter meat the line if you will.

 

Now start your encoder in NextKast.  Turn on your SainSonic AX-05B and set the frequency to a blank one.  Your done and sounding Rock Solid.  The 1/4 mile range is on High Power.  You’ll have to follow the instructions for High Power as out of the box you get -48dbm.  It is far less than 1/4 mile as there is some fade when you walk around the house in a few areas.  But this transmitter sounds great.  Best I’ve heard under $300.

[Thelegacy Total posts : 0]

When I put the whole string in google I did see the FCC database with the certification for the transmitter.  I don’t know how you got the revised one as 50uS because I was told it was 75uS.  Maybe it would have a little more highs at 75uS but still it does not sound too bad compared to some other transmitters I’ve heard.  I don’t have a scope to really tell if it is 75uS.

[wdcx Total posts : 0]

If you go directlt to the FCC database Sainsonic has only 1 product certfied and it is not a FM 88.1 to 107.9 transmitter. They falsly state on the web site that it is certifed.

[Thelegacy Total posts : 0]

https://fccid.io/document.php?id=2216818

 

As you can see there was two versions of the transmitter.  One with the BNC and the other with the TNC (Revised transmitter).  I don’t know why you could not find it in the FCC database but when I went to google and entered the string for the FCC ID# it did come up.  You can even see the inside circuit and it does match the CM-10 except that it has a connector and a rubber duck instead of the telescoping antena on the Decade.  Plus you can see the full name and entities associated with SainSonic when you open this link.  I did’t see any froud here.  It all looks liget here.  Hope this helps.

[wdcx Total posts : 0]

That is a bogus site. The FCC does not sell advertising on thier site.  Here is where you want to go: https://apps.fcc.gov/oetcf/eas/reports/GenericSearch.cfm

 

[wdcx Total posts : 0]

http://www.am1000rangemaster.com/pdf/nwxam1000.pdf

[Thelegacy Total posts : 0]

I swor I found it before.  I’m not sure why it has to -48dbm and why at low power it acts like most of the part 15 transmitters out there.  Plus the manual has the usual stuff about part 15.  If they faked this they did a really good job of it.  I’m just wondering if there is a reference issue here.  If I just do the grant code I come up with other stuff from SainSonic but not FM Transmitters.

[MICRO1700 Total posts : 0]

I sure didn’t know any of this.

Very good stuff.

Brooce, DOGRADIO

[ArtisanRadio Total posts : 0]

The Sainsonic was certified.  But then a little while ago they applied to get that certification revoked, and they stated that they had not sold any transmitters in the U.S.  It’s my guess that is why the certification is not in the FCC database.  A lot of this info can be found at the Radio Insight forum.

[wdcx Total posts : 0]

No reference issue.  I have been working with the FCC for years. Sainsonic ONLY has the items you found on the database.  If the site does not end in dot.gov you are getting hosed.  Typical of Chinese crap as they plagiarize whatever they can!

[Thelegacy Total posts : 0]

I will admit there’s a lot of fraud coming from China on the Internet however in this case this Transmitter is not crap it’s just that the way they try to represent it might be a little bit fishy. It is a well-built unit and at the – 48dbm setting you are obeying part 15 fm rules.  And since the Transmitter used to be certified I don’t think you’re breaking any laws by owning it. You’re just going to have to be careful with it and don’t do anything stupid.  The low power setting will get you a few feet away from your house and that’s only on a good radio as if I sit between the transmitter and Radio there is fade just like typical part 15.  It is compared to the Whole House FM transmitter 3.0.  I don’t think the unit is bad if I did I would had sent it back.  Im not sure the C. Crane has 75 Us pre emphasis.   Do what you will but this transmitter is the same as a Decade CM-10 and me being disabled I cant afford $200.  I thought I got a good deal.

[ArtisanRadio Total posts : 0]

I don’t know why you’re getting your knickers in a twist over this, John.

There’s a thread over at Radio Insight on the Sainsonic in the Community Radio section.  They did have something certified at one point, and then asked for the certification to be rescinded.  I don’t know whether it was this transmitter, or something else, and others are claiming something else, but like anything Part 15 FM coming from broadcasters, I’d take it with a grain of salt, as there was no reference associated with the comment.

It appears that theLegacy purchased this transmitter in good faith, as Sainsonic is putting the certification number they did have on the box.  Ultimately, it’s up to the end user to determine whether or not they are complying with the rules.

I’m also not so sure that I’d call the transmitter junk without doing an analysis of the signal that it produces (and I don’t think that has been done, at least that I’ve found).  Saying that all Chinese transmitters are junk without having any data to back that up is just beng silly.  The Decade CM-10, for example, is certified, is eerily similar to the Sainsonic, and comes from China.  Has anyone done an analysis of the Sainsonic’s signal?

[mram1500 Total posts : 0]

And besides, nothing says a transmitter has to be certified to be USED.  Only needs certification to be mass produced and marketed.

[wdcx Total posts : 0]

I dont think anyone said that.

[MICRO1700 Total posts : 0]

This computer is killing me.

Back to the thread, which is wonderful,

by the way.  I’m disabled too.  Most of

my vision is way over on the extreme left

side, and the vision that is there is not very good.

So here’s why the Sansonic would be good

for me.  The good digital display and the metal

case – i.e. – it wouldn’t get pulled off of a table.

These plastic transmitters…  Although I have to

say, the C Crane has been a VERY FAITHFUL friend,

as far as “electronic friends” go.  It’s over at another

Part 15 station on the other end of town.  I lent it and

a mixer board out.  I’ve had it for 10 years or so.

What worries me about these things coming out of

China – how do you really  know what production run you

got?  Maybe the RF out has a big spike in the 108 to

136 MHz aircraft band. 

There were a bunch of other things I was going to

say – but that will have to wait for another later

post.

Best Wishes to All,

Brooce, DOGRADIO

 

[MICRO1700 Total posts : 0]

that has been on this board in a while.

By the way, I’m disabled too.

You know why the Sainsonic is so tempting

to me?

The metal box and the fact that it won’t get

pulled off of a table.  Also the digital display

that I can see.  I’m legally blind.  The vision

that I have is way way over on the left side of

my head.  (Oh yeah, there’s the low price too.)

Anyway, though – I get uncomfortable unless I

can see the RF output on a spectrum analyzer.

How do I know I got the right production run?

How does the distributor know?

Somebody said not too long ago, “Gosh, what a

dumb thing it was to put the FM broadcast band

next to the aircraft band – whose idea was that?”

If I got the wrong production run – the thing could

have a spike on Bradley approach (the local big

airport)  or something.  That would be BAD.

As a ham operator I learn stuff like that when I

was a kid.  o

[MICRO1700 Total posts : 0]

another one.

There might be part of a post that

got up on the board.  It’s not proofread.

I’m just going to leave it there.

Best Wishes,

Brooce, DOGRADIO

[MICRO1700 Total posts : 0]

they both say about the same thing.

You can take one out if you want.

I guess I’ve hit my limit here.

Best Wishes,

Brooce, DOGRADIO

[wdcx Total posts : 0]

No knicker twisting here. 🙂 If you carefully reseach my posts I was refering to the phony FCC site the Chinese folks created. Also, I contacted Sainsonic a while back and they could make a special order with 75 uSec pre-emphasis but as shipped they were 50.  A neighbor about a mile away has a Sainsonic. It goes way below the FM band as well as above.  His is 7 watts with the same FCC ID as the that we have been chasing around. Huh? 

But note that the CZH-05B can be a Sainsonic, Fail-Safe, CZHFM, FMuser, etc.  You get the idea.

The Decade unit is manufactured by Artika. So I am guessing the others are knock offs.

[Thelegacy Total posts : 0]

Their website says 100mW-500mW when in actuality when I got the transmitter it was -48dbm low and 500 mW high power.  Im sure when the transmitter is recertified with the same FCC identification number it will have information to reflect that.  That transmitter design has been changed and the box and manual reflect that but the website does not have all the correct information.  This is probably why they requested to have it removed so that they can get the information correct.  It would not make sense to certify a transmitter that is not sold in the United States. So that’s not the reason I think the reason is that the information was cross reference and did not match.  They have to get the information 100 percent right. So on the website its still saying 100mW-500mW.  There is no reason for them to make a Transmitter at- 48 dBm. Unless they intended to have it certified for part 15 rules.  Its very confusing to the public because there has been more than one version of the sainsonic Transmitter. So I see 3 versions so far. This is why there was a problem with certification because the unit in question all looks the same but there are differences in them. One very important one is the low power setting.  Trust me this is very different from the version with the BNC connector.  FailSafe’s CZH-05B also has a TNC connector but the low power is 100 MW and not – 48 dBm for the low power setting. Both these Transmitter are made in China by the same distributor who distributes  to different retailers with different brand names This is why they needed to get the the informa updated properly.

[Carl Blare Total posts : 0]

First of all the name sounds like “Saint Sonic.” Wow, a Catholic FM transmitter from the Vatican!

The confusion over different versions and certifications reminds someone of that AM transmitter that had 300′ of coax and a remote ATU (Antenna Tuning Unit) that flowed against normal Part 15 logic.

Back when that transmitter was the buzz of the forums there were members who desperately posted “Can’t we talk about something else?”

It hasn’t reached that point yet with the Saint Sonic, but that other transmitter finally got removed from certification and vanished into history.

[Thelegacy Total posts : 0]

MICRO1700: I only see out of my left eye.  I can tell light from dark on the right eye and sometimes see movement.  My issue is the optic nerve.  I have tunnel vision out of the left eye and read with an 8X magnifier as well as use the magnifier in Windows 8 (modified to look like Windows 7 with Classic Shell).  It was the reason that I bought the Sainsonic.  Sometimes I drop things and it was one of the reasons the transmitter I had in Michigan blew out.  I didn’t notice after I bumped it that the antenna had came lose and when I powered it up all was well till I walked out of the room and the connection lost good contact.  When I came back I smelled something and noticed I was no longer on the air.  The transmitter had fried.  So before I bouht the Sainsonic I wanted to make shot gun sure the antenna had a good connection.  Even those BNC connectors had issues with being lose and could cause a transmitter’s final to melt.  When I noticed you had to screw this connector in I said “This is the one I want!” and done some more reading.  Now after I placed my order I quickly asked for the 75uS pre emphasis but I have no way to verify its true 75uS other than James saying “Yours is 75 uS pre emphasis No worries.”  It does have a slight more base than other stations BUT NOT SO IT SUCKS HOWEVER but you can tell my station is not pro at times because it doesn’t modulate the same way and I also don’t push the modulation.  James had told me not to try and make it as loud as a regular station or I’d overmodulate the transmitter and eventually cause the audio circuit to fail.  He also reminded me that missuse is not covered in warrenty.  And for those who are thinking of transmitting without an antenna Never Do That!!  Some of the transmitters without finals you may get away with it but still I’d not do it.  Now there is a HLLY transmitter with a variable 0-1 Watt and I thought of buying that it was the TX 01S but didn’t get any reviews of it and I was afraid of harmonics.  And by the way speaking of watts I found that -48dbm equals 15.8 Nano Watts.  I think I read where someone said the Whole House FM Transmitter 3.0’s part 15 setting is 18 Nano Watts.  So the part 15 setting should be true part 15 as far as that goes.  We all know the high power end in the USA is gray and even if you do deside to do it if you live in a Metro area its gonna get you busted really quick as the experimenter I know told me it would go 1/4 mile at that level.  If your in a metro area at that power level you’re gonna get a complaint from an NAB station or possibly a Ham operator who is trying to win a tranceiver from the FCC.  So especially in those areas you want to stay at -48dbm or 15 nano watts.  And that 7 watt transmitter your talking about gets really Hot.  Temperature wise I mean by Hot!  the fan inside is cheap and will fail quickly.  The antenna it comes with is telescoping and will transmit more than 20 miles Inside Your House on the second floor (Per Youtube Test Video).  Bad reviews of this transmitter even came from Amazon and Youtube itself due to the poor quality of the circuit of this transmitter.  SainSonic won’t sell it on their site and James and I had a talk about that unit.  It was never supposed to be sold in the USA but Amazon is selling it and one person got injured due to the heat that transmitter puts out.  7 Watts Really?  That is some crazy insane power to try on an inside antenna!  Someone is gonna get a nasty RF burn when they accidentally tuch the antenna while their transmiting on High Power.  I bet they’ll never do that again.  I did that once on a CB and I never done it again lol.  The wash out over the dial I bet is more than 150-200 feet I bet the first time someone done that for an hour they are gonna have the feds at their door with a bettering ram and guns drawn.  Stupid insane I say.  Even at the 1 Watt level that transmitter got Hot as well.  It just sounds like pure junk and that is what gives all Chinese transmitters a bad rap.  Some are POS’s like that one.

[MICRO1700 Total posts : 0]

It sounds like our situations are pretty

similar.  What are the odds of that?

Thanks again for the info.

I’ve got to go.

I would really like to figure out a way so 

we can talk.  We’ll have to do that.

Best Wishes,

Brooce, DOGRADIO

[Thelegacy Total posts : 0]

If you tune into my station (See my signature) you can talk to me.  I usually have the Google voice forwarded to my cell so that won’t be an issue.  I’m sure we can catch up on some good stuff dealing with FM Transmitters.  I’m sure we can share ideas as well.  I’d be more than glad to help those who want to make a change for Radio and part 15 for the good.  As long as your not an Anti FM troll I’d be glad to help those.  But then again that is why I have apps that block the bad guys lol.

[MICRO1700 Total posts : 0]

Oh trust me, I love streaming Part 15

stations and finding out about them and

the people who run them.

I will show up to talk to you hopefully soon.

But we have the eye thing in common too,

and I’m wondering how you deal with it.

I try, but I need to do better.

Very Best Wishes,

Brooce, DOGRADIO

P.S.  Oh, I’m not an anti-FM troll,

either, but it sounds like a good idea

for a comic strip or something.

(I was a cartoonist in early life.)

[Carl Blare Total posts : 0]

Can’t remember if I’ve already blogged about it, but I fancied the idea of starting a “Troll Patrol,” but then realized that to carry it out we’d need to become trolls in search of other trolls.

That’s probably why U.S. spying is such a mess.

[wdcx Total posts : 0]

WE should also monitor those who do not wash their hands when departing a restroom.  We can issue “Golden Handshake” awards.

[Carl Blare Total posts : 0]

Big greasy finger blotches on vinyl discs, crud on headphones, gummy telephones, strange aromas from the waste basket, it’s public radio.

[MrBruce Total posts : 0]

Okay, let’s talk about Chinese transmitters for a bit.

Like any person who likes broadcasting as a hobby, I like visiting websites that carry AM and FM related equipment. Be it receivers or transmitters, or equipment that helps either end of the hobby.

I have seen some high powered FM transmitters out there, that are sold on line and also the same units are sold on ebay.

Looking at the internal designs of these transmitter, by way of published photos, showing the transmitter with its top cover removed, has shown quite a few have internal 5 poles for filtering to cut the 109MHz to 216MHz 2nd harmonic range from reaching the external antenna.

Some of the designs I’ve seen, make me wonder why anyone would claim that they cause interference to the air craft bands of VHF television frequencies.

I would love to see studies done on those transmitters, the only problem here in the USA is they are virtually illegal to own, because their RF power output seriously exceeds part 15 FM for the USA and are not certified for any use. But I’d be willing to say, that NOT all of those Chinese FM transmitters are prone to creating interference, that to me is just a myth the licensed broadcasters come up with because those transmitters can be adjusted from 1 watt to as much as 1000 watts.

In almost every case against a person who got an NOUO from the FCC, there is 99 3/4 percent of them that claim the station was causing interference to a licensed station or other service.

Although some cases may be same channel interference, most are about a pirate station interfering with a licensed station on another channel, or the air craft band. Is that really true? Or just a false reason to remove the completion?

Bruce.

[Thelegacy Total posts : 0]

Or like RIKA FM who knew they were causing interference and did not care.  The 01S was a transmitter I thought about because I could adjust it from 0-1 watt.  Id set it to 1mW or till I could reach 800 feet on a car Radio.  But there may be times I only want to transmit 30 feet and id adjust the power so my private messing around isn’t heard outside my house.  Especially just using my stereo like wireless speakers.  Its why I wish my tx could do that.

[MrBruce Total posts : 0]

Most of us care about causing interference in my personal belief and want to avoid it at all costs.

Not caring only gets you shut down a lot quicker.

Here is my theory, I personally believe that any transmitter out there AM or FM can be made to stop creating interference.

Even if it does, there are ways to stop that interference if anyone one really wanted to and I am not saying that is done by simply shutting the transmitter off either.

I am in the USA and don’t wish to import equipment that may get me into trouble with the Federal Government. But I’d really like to be allowed to do tests on such equipment to see just how junky they really are. But there is a risk factor there I do not wish to take.

I’ve always wondered what the FCC does with the equipment they seize from pirate stations. Where does it go after they seize it? Has anyone ever asked? Does anyone even know? Or does everyone just not care? I know I’m curious.

I do look over the equipment that is sold by various websites that sell AM and FM transmitters and several show the inside of the cabinet where the audio processing circuit boards and amplifier section of the RF power amp. I see signs of a filter, similar to those band pass filters I see for FM. If there is a 5 or 6 pole filter, and it is designed to block everything above 108MHz, how is there going to be interference to the aircraft bands above 120MHz?

As for spurs, if signs of your signal on another portion of the FM broadcast band is the issue, I know of licensed radio stations in my area that interfere with other portions of the FM broadcast band. This is not always a case of a poorly designed radio receiver, it is a case that at 15,000 watts ERP, your truly going to interfere with something.

Case in point, WBMW 106.5MHz recently went from 10,000 Watts ERP to 25,000 Watts with a move to a new tower location and an authorized power increase of 25,000 watts, you can hear them bleeding over various other parts of the FM band as far away as 15 miles from Stonington, CT. which is where their new tower is located. They were formerly transmitting from Ledyard, CT.

Nothing has been done about that and it still continues to interfere with 107.1 and 107.3MHz.

Now back to those Chinese transmitters, I personally do not believe that every complaint made about interference is 100% truthful. When it comes to a licensed station filing a complaint against an unlicensed station, their most successful complaint is that unlicensed station was causing interference to our listeners ability to listen to our signal, even if that is not really the actual case.

Now as far as WBMW goes, their interference does not interfere with a station on 107.1 or 107.3 that covers the area they interfere with. WAAF on 107.3MHz from the Boston, MA market does not have a 30dBu contour in southern Connecticut and there are no stations on 107.1 MHz that serve this area, one is in Hampton Bays New York and the other is in the New Bedford MA area.

I may be wrong, but without actual testing, we can not be sure one way or another if those Chinese transmitters really actually cause interference.

Now as far as those unlicensed FM or AM stations out there that actually cause interference, what are they using and why don’t they look into some type of filtering to avoid this interference in the first place?

Transmission line filters are available for both the AM and FM broadcast bands, they should stop the 2nd and 3rd image from leaving the antenna and they don’t cost more than 50 to 130 Bucks tops. Spending that money could save an operator that $25,000 fine for creating interference.

That’s my opinion and I’m sticking to it.

Bruce.

[wdcx Total posts : 0]

Bruce:  I am told by the FCC that seized equipment is destroyed if it is not being used as evidence. Now in a case in South Florida a few years back, the Delray Beach PD seized a transmitter from a pirate radio station after it was shut down under Florida’s Pirate Law. The PD contaced the FCC in Miami but they never responded. After some time, the PD returned the transmitter to the pirate operator. That was the last the PD is ever going to do the FCC’s job again. True story.  I know the cop that handled it.

[Carl Blare Total posts : 0]

Here is your schematic for the C.Crane FM1 Transmitter

http://scwis.home.comcast.net/~scwis/files/ccsch.pdf

[Carl Blare Total posts : 0]

As suggested by Bruce MICRO 1690/1700 Dog Radio Studio 2 WLP 1590, I am going to use the official FM Channel Numbers in place of frequency when identifying any of the KDX-FMs.

If you do not have a chart showing the FM Channel Numbers you can assemble your own chart by simply knowing the beginning and the end of the numbering:

Channel No. 201 = 88.1 MHz

Channel No. 300 = 107.9 MHz

To raise a related matter, the channels 201 to 220 are designated as non-commercial channels, and all those 221 and above are commercial channels.

Yet a Part 15 station operating in the non-commercial portion of the FM band can operate commercially and be entirely uneducated,

[MrBruce Total posts : 0]

Carl Said:

To raise a related matter, the channels 201 to 220 are designated as non-commercial channels, and all those 221 and above are commercial channels.

MrBruce Says: That may have been true at one time, but now channel 221 through channel 300 has many LPFM’s scattered about which are non-commercial in nature. I’ve seen some licensed high school radio stations in the upper FM band region as well.

I do realize LPFM is a totally different class of radio station service, but in the old days, all stations above 221 were commercialized radio services.

Bruce.

[Nate Crime Total posts : 0]

I’m surprised it’s that much to the circuit! Some of the small FM transmitters for mp3 players have just a couple of ic’s and a few dozen other components on a board to fit the case and that’s all. If that’s what CCran is still using, that’s great, audio limiter diodes, MAX drive chip and tuned circuit on the ouptut.

[Carl Blare Total posts : 0]

I think a main deal about the Version 2 C.Crane FM is an improved FM synthetic chip.

I believe I read that in a review linked somewhere in this maze.

[Thelegacy Total posts : 0]

I wonder if the new one has the same range?

[Rich Total posts : 0]

RE: The clip below from the opening post of this thread:

… FCC Part 15 compliant FCC ID # 2ABT5AX05B7C Low Power -48dbM/500 mW (To adjust power hold down the power button while unit is unplugged then plug power in. Press Down arrow to switch to -48dbM or up arrow for 500mW Click power to confirm. …

A power of 500 milliwatts is +27 dBm.  If the text above is accurate, then the output power of that unit is adjustable over a range of 75 dB (a ratio of more than 31.6 million to 1).

Just to observe that an r-f attenuator or otherwise adjustable circuit of that range and required accuracy would cost far more than the transmitter itself.

[Thelegacy Total posts : 0]

So are you saying that the High power is NOT really 500mW (as I suspect)?  That would really make more sense as to why the low power was so crappy and I could not go far at all as compared to the Whole House Transmitter 3.0.  To me I don’t think I am breaking any rules here at all.  We’ll know for sure when the real tests with the Potomac FM-71 is done.  But if the Decade CM-10 is no longer made I wonder if it will also cause SainSonic to have to stop their AX-05B (unless they copy the circuit themselves)?  If they want to continue making (or reselling) transmitters they would have to go with Ramsey and assemble all of them and then have each kit certified as a fully assembled unit.  So far I see no mention of not making SainSonic on their website.  Still I’d like to see the test done to it as I suspect the supplier is HLLY.  I don’t know how they would have done it in the IC Chip to switch between the high and low like that unless they have two separate routes for the signal to pass.  Switch to low power it goes through some sort of resistance.  the Transmitter is not that big so there is only so much they could do.

[Rich Total posts : 0]

Clip from Reply #58 above:  So are you saying that the High power is NOT really 500mW (as I suspect)? …

I posted nothing that would deny the power values you expressed either in milliwatts or in dBm in your original post.  I have no basis for such denials.

All I did is to comment on the difference between them, and to point out the technical difficulty and cost needed to (accurately) produce such a range of output power.

Note that the transmitter output power needed to exactly meet the field strength limit given in FCC §15.239 depends on the configuration/gain/impedance match of the transmit antenna it uses.

A power of about 11.43 nW (0.000 000 011 430 watts) applied to a matched 1/2-wave dipole transmit antenna produces that maximum field.  Not much more power than that would be required when using a very short and electrically inefficient transmit antenna — in almost most cases less than just 1 milliwatt.

So it is unclear as to the reason that some domestic/international manufacturers and their distributors offer (uncertified) transmitters for the FM broadcast band with advertised output power ratings of 10 mW, 25 mW, 35 mW and more for use as “Part 15 FM” transmitters.

Caveat emptor.

[Carl Blare Total posts : 0]

Here is another transmitter that claims Part 15.239 specs

http://www.canakit.com/usb-fm-transmitter-kit-ux300-ux300-ca-ux300-ex.html

[Thelegacy Total posts : 0]

Only 7 frequencies which sort of kills that transmitter.  Otherwise it looks like it is made really well.  Since it has a built in sound card the audio quality would be really clean.  It use to be on sale for $89 at one time.

[Carl Blare Total posts : 0]

I’ve been made aware that the junction between the telescoping antenna and the circuit board depends on a spring-tension clip, a piece of shiny-smooth metal with two-teeth at the contact with the RF spot on the circuit card.

In too many cases that technique has failed, as in our case, solved by soldering a wire in place of the telescoping antenna.

To restore original conditions I may fabricate a better antenna connecting method so-as to restore the certified antenna.

[Thelegacy Total posts : 0]

Drill a hole in the antenna at the bottom and then buy a horse shoe connector and  solder it to the small wire and screw rhe screw into the hole with the horse shoe touching it.

[Carl Blare Total posts : 0]

The bottom of the telescopic antenna has a screw that firmly attaches the spring-tension metal, which bends downward like a phono-styles where it is meant to pierce into the solder bump at the RF point of the card.

Therefore the telescopic antenna already has a firm attachment screw, so we need a piece of metal that can be soldered down below where it touches the card.

There could still be a problem as the antenna is swiveled and adjusted, putting tension on the connection… but that can be solved by using a piece of highly flexible braided shield wire which can absorb the movement.

I might even install an RF output connector so a cable can be run to an antenna at a different location.

The certification allowed C.Crane to market the transmitter. It does not obligate me to do or not do anything.

Only 15.239 is of importance to my use of the transmitter.

[Carl Blare Total posts : 0]

By “Holy Reviews” I’m taliking about a review of the Wholehouse 2.0 that is full of holes. I ran across it at a website somewhere.

In the “includes” section of the so-called “review” there was no mention of the small lavalier microphone packaged with the transmitter that effectively allows using the Wholehouse as a wireless mic.

Tonight, after owning the Wholehouse for several years, I thought I’d test the microphone function.

From the outset it sounded distorted even when I turned the modulation level down, and the graph on the Audacity screen showed flattening (clipping) at the top and bottom of the display.

By backing several feet away from the microphone I was able to hear it without distortion.

Conclusion, the microphone pre-amp inside the transmitter is set very hot and has no adjustment.

Go figure.

[Carl Blare Total posts : 0]

Here’s a very good one about the C.Crane FM 2 Transmitter

C.Crane FM Transmitter 2

[wdcx Total posts : 0]

There is NO WAY this is FCC Certified with a starting freq of 76 MHZ. 🙂

[Thelegacy Total posts : 0]

If out of the box the transmitter does not drop down to 76 Mhz it still can hold the certification. But yes I know it should not be reprogram able to drop down to that frequency, but since Radio’s in the USA can’t receive that far down who is honestly going to drop an FM Transmitter to 76Mhz in the first place? Also the Whole House FM Transmitter 2 and 3.0 are both certified and yet can be programmed for higher power. Nowhere in the manual does it talk about this however. Hackers figured it out and published how. That is not the fault of the manufacturer that their logic circuit was hacked. It only proves that the circuit for the Whole House Transmitter 3.0 may not have originated in the USA. SainSonic however as well out of the box is set to low power and 88.1-107.9 Mhz. If you re program it yes you can go to 76 Mhz. They talk about the High power mode in the manual however so again its gray on that one. Ramsey’s FM Transmitters on some web sites are being accused of not being certified or somehow “Cheating” on the rules. But no one (Yet) has had a full 250 uV/M (Tested by the patomac FIM 71) and was able to report that range. Again all of this is dodgy and speculative until we have concrete solid testing and data. Hopefully in a few weeks Tim will be able to start to debunk some of the speculations running around for several years. I thik it may even surprise that other site as well.

[Thelegacy Total posts : 0]

Good point carl I wondered when that would be brought up.

[Carl Blare Total posts : 0]

Someone will eventually spill the beans, so you might as well hear this from me.

It’s true that I just ordered a C.Crane FM2 Orphan Transmitter.

Why would I do that?

After learning that the Wholehouse 2.0 puts out spurs all over the educational band, I needed a reliable transmitter that won’t cause inteference.

“Orphan” transmitters are those returned by unhappy campers and offered for re-sale by C.Crane, $10 saving.

Some people return those when they discover it doesn’t go as far as needed.

All this talk about Part 15 FM has me filling every blank spot on the dial.

[Mark Total posts : 0]

I hope they check it to make sure it’s ok and not been tampered with….they don’t mark orphans down that much. A new one  for $10 more may have been best. I’m just wary of things like this.

 

Mark

[Thelegacy Total posts : 0]

Maybe the orphan transmitters have been set to Full legal porwe.

[Carl Blare Total posts : 0]

I think C.Crane states that the “orphans” have been checked over to assure their condition, but we shall see.

I knew a woman who tried a C.Crane FM Transmitter and was very displeased and returned it.

With their stub antennas they give such poor performance that you might as well just skip the radio and use your ears straight to the CD player, but with an improved antenna and checked for Part 15 field strength they get better.

Even orphans can be returned.

[Thelegacy Total posts : 0]

We will have to see if there is any difference in range.

[Carl Blare Total posts : 0]

For your convenience here again is Radio Jay Allen’s Review of the FM2, indeed mentioning the new improved chip, improved signal to noise ratio and other upgrades.

I don’t see that he talked about range at all.

C.Crane FM Transmitter 2

[Thelegacy Total posts : 0]

I don’t know why Range was not talked about in the article.  He did talk about the audio quality.  It may stand up against SainSonic’s Audio which in my opinion is very good.  Its very clear and not too muddy but you really have to pay attention to the way you drive the audio of the transmitter.  Since NextKast has audio compression built in this is a very nice companion to any FM Transmitter but really works well with mine.  I could imagine the C. Crane would really sond good with NextKast as well since they do have the indicator to warn when your over modulating the transmitter.

[Carl Blare Total posts : 0]

Sitting on a home frequency is what licensed stations do. They are only able to move to a different spot on the dial with great effort, expense, and might not be able to do it at all.

Part 15 is a different animal. It can change frequencies as often as desired, using the good practice of charting out clear channels.

Following many days on a single frequency it began to bother me that strangers might discover the programming and tune in as a habit, so I jumped to a different frequency without notice.

The wonderful disappearing radio station.

Why would anyone try to dodge the potential audience? That’s an easy one. KDX is not seeking a radio audience of strangers. KDX exists as the personal customized radio station of Carl Blare.

At times KDX is only AM, at other times FM, flitting around the dial.

The ultimate will be when they all get turned on at the same time.

[Carl Blare Total posts : 0]

One of my measuring devices is a Grundig Satellit 750 Radio with S-meter, range 0-5.

But on the FM band the S-meter sits on 4 across the whole band.

The other bands are ok, AM and SW, the meter ranges from 0 up to 5. But on FM everything is always “4.”

Where can one turn, what is there to do?

[Thelegacy Total posts : 0]

Either the meter was not meant to measue FM or the voltage inside the Radio to the meter is too high when on FM.  Not too sure if there is a way to calibrate the meter or not.  Brobably would have to know a radio repair man that would even be willing to mess with the meter in the first place.  Heck I’ve seen CB meters do the exact same thing you just mentioned.

[Carl Blare Total posts : 0]

The C. Crane FM1 (and FM2) has a battery compartment for 2x AA batteries, which I installed with new batteries.

The antenna on the C.Crane was at 7″, frequency = 89.5 MHz.

The AT5005 Spectrum Analyzer was in its permanent position in the NW corner of Blare Towers Executive Office desk with telescopic antenna raised 14″.

How close to get a maximum reading on the scope? Anser, 4-inches = 80 dBu.

In order to set the scope for a stronger signal I’d need to push a -10 dBu attenuator button, but I keep it set at “wide-open,” no attenuation, because no signals exist in my vicinity that exceed the analyzer’s range in this mode.

The C.Crane was moved to the center of the office onto a 2-foot stack of books for a reading of 50 dBu.

The C.Crane was set in the SW corner of the office by the copier, 30″ above the floor : 50 dBu.

Just inside the doorway of the next room the C.Crane was set in its “usual position” on top of the computer : 50 dBu.

In the center of the computer room, known as the Vacuum Room, along the western wall the C.Crane was placed at the base of Tower 1, a bamboo indoor tripod tower : 39 dBu.

Mounted also on Tower 1 is Wholehouse 2.0 which was set to 106.9 MHz : 34 dBu.

Out of curiosity I re-tuned Wholehouse 2.0 to 89.5 MHz for comparison : 48 dBu.

Returning to the C.Crane it was set center of Vauum Room on a foot-stool : 38 dBu, and for an unknown reason the carrier was pulsing up and down about 1 dBu. The overhead (3) lightbulbs are LED type, possibly interferring.

Moving to the center of a third room, the Upper Management Lounge, C.Crane : 38 dBu.

Top shelf of tall (5′) shelving unit by Panasonic Radio, C. Crane : 33 dBu.

Because the Wholehouse 2.0 had exhibited different power outputs at different frequencies, I set C.Crane to 106.9 and tested it from base of Tower 1 : 20 dBu.

Last, I placed C.Crane within 4″ of spectrum analyzer antenna : 61 dBu.

Main Observation : These Part 15 certified transmitters output different field strengths at different frequencies.

[Thelegacy Total posts : 0]

Which one was more even the Whole House or the C. Crane?  I see where the Whole House was 10 dbu above the C. Crane on some frequencies.

[Carl Blare Total posts : 0]

The Wholehouse 2.0 is overall stronger in this present test.

Wholehouse 2.0 : 89.5 MHz = 48 dBu ; 106.9 MHz = 34 dBu.

C.Crane FM1 : 89.5 = 39 dBu ; 106.9 MHz = 20 dBu.

IMPORTANT DISCLOSURE: The telescopic antenna (fully extended 12″) is temporarilly removed from my C.Crane FM1 due to a defective coupler to the circuit card, and is replaced by a 7″ vertical wire. Therefore with the full 12″ certified antenna the readings would be higher.

What’s To Come –

This week I’ll receive a C.Crane FM2 and will annoint it as the new laboratory standard certified FM transmitter.

What I’ll do right away is sweep the band to report on how output fields vary from low to high on the dial.

[Carl Blare Total posts : 0]

The C.Crane FM2 Transmitter arrived already… how did the C.Crane Company get it here so fast?

Funny, I heard a bonk out on the porch and saw that the mailman had dropped the box, but I wasn’t worried. These little transmitters are made to withstand being dropped and stepped on.

Meanwhile, I had repaired and restored the 12″ telescopic antenna on the FM1.

So I set them up side-by-side, outfitted with new double-A batteries, 16″ inches from the spectrum analyzer, and looked at low band, mid-band, and high band FM.

FM1:

89.5 MHz = 53 dBu

101.5 MHz = 43 dBu

106.9 MHz = 45 dBu.

FM2:

89.5 MHz = 50 dBu

101.5 MHz = 48 dBu

106.9 MHz = 44 dBu.

MY FINAL REMARK: These certified FM transmitters are all putting out more or less the same field strength, varying across the frequency band.

[Thelegacy Total posts : 0]

Interesting Test and though the FM2 may be a little better yes it is so close there really isn’t much difference.  I’d like to see the difference between that and the Whole House FM transmitter 3.0.  Plus I’d like to know how far it could possibly be received in its stock condition.  Actually Marc did a pretty good test with it and he got 800 Ft.  So we’d have to see what Tim gets out of his.  Maybe the key is the building and the area around you.  AM at least does have potential for more legal range as far as I can see.  I’d like to see what can be done with the Talking House or the AM Stereo transmitter I saw in the video.  The night time inversions do kill it for me and I don’t want to cause any issues so I go silent when this happens.

[Carl Blare Total posts : 0]

These little FM transmitters down here inside the house sort of get 200-feet.

If they were up on a chimney mast above the house then we’d be seeing 800′ or better.

That’s the way it is.

[Thelegacy Total posts : 0]

OK at least your getting that.  Like I said on Low Power I’d only get 20 feet at best.  200 Ft would be about from my house to the house next door maybe the one after that.  So at least your doing pretty good.  Actually better than other reports I’ve read about the C. Crane.  So looks like the coupler was the issue between the antenna to the circuit board.  They just need to make sure all their transmitters are soldered or whatever way they make that connection is a solid one.

[MICRO1700 Total posts : 0]

I love it!

Brooce, WLP

[Carl Blare Total posts : 0]

From an FCC Report and Order dated August 5, 2015, in review of accomodations for wireless microphone users in the core VHF & UHF TV bands under Part 74 and Part 15, this section directly addresses the FM band and 15.239:

b.

88

–

108 MHz FM Band

67.

Background.

As discussed in the

NPRM

, wireless microphone operations have long been permitted in the 88

–

108 MHz FM band on an unlicensed basis under Section 15.239 of our Part 15 rules.

174

While we did not propose any rule revisions in the NPRM

, we sought comment on whether wireless microphone users continue to make use of this band for their operations and the extent to which existing or revised rules will be useful for accommodating wireless microphone users’ needs in the future.

To the extent that revisions were proposed, we requested that parties submit technical information in support of their proposals, as well as analysis of the benefits of such revisions and likely impact on FM broadcasters.

175

68.

We received few comments regarding wireless microphone use of this spectrum, with no commenter suggesting that the band offers potential for supporting significant future use. BSI states that the FM band is not useable for wireless microphones that support program production, and that there is no room in that band for wireless microphones generally, without fear of interference to and from FM broadcasters.

176

Similarly, SBE asserts that, while some unlicensed, low

–

power wireless microphones have been manufactured for t

he FM band, the potential for interference to FM radio reception in major markets is far too high to permit such use.

177

Moreover, Sennheiser contends that the FM band has exceedingly limited potential for wireless microphone use because antenna length requ irements are very cumbersome for either worn or held microphones.

178

Along those same lines, Shure maintains that the wavelengths in the FM band are too long to be acceptable for most contemporary wireless microphone applications.

179

69.

Discussion.

Based on the comments and record before us, and the apparently minimal

opportunity for making use of this band, we decline to make any revisions to the rules applicable to wireless microphone operations in the 88

–

108 MHz FM band.

 

 

Back to me – a careful reading of this text demonstrates that the FCC has been reviewing the status of 15.239 in relation to wireless microphones. The conclusion is that they decline any change to 15.239.

[Thelegacy Total posts : 0]

Well this sounds like we may be looking at an oppertunity for extended part 15 now that they are revisiting part 15:239.

[Carl Blare Total posts : 0]

It says that the FCC looked at 15.239 in regard to wireless microphones and it says they decided not to change anything because the FM band is not suitable for wireless microphones.

[Carl Blare Total posts : 0]

In his duplicity our good buddy Carmine5 is giving advice for us but posting it at hobbycaster, referring to us as “the good folks on the other site.”

He thinks we should forget FM and petition the FCC to open up other bands.

But since, according to his earlier posts, we are magical thinkers living in a fantasy world, I suggest we stick with our fantasy and let him can keep his.

[Carl Blare Total posts : 0]

Based on observations by me and others, the certified transmitters we’ve inspected have very carefully isolated RF ground well out of reach of the user.

It seems obvious that the reason for concealing the RF ground is to discourage implementation of full dipole antennas, which could result in range well in excess of 15.239.

Do you agree/disagree with this opinion?

[timinbovey Total posts : 0]

Based on what I’ve observed on the Decade CM-10 and wholehouse 3.0 that I have received in the past few days.  There is no access to RF ground, and in fact the “Reverse SMA” connector on the WH 3.0 is listerally just a 1/4 x 36 bolt with no center conductor at all and the use of this bolt is certainly no way to prevent ssomeone from connecting whatever the heck they want to this output terminal. 

After I do my field strength reading and range work I’ll be taking these buggers apart to see what’s up.  I really want to put them on an RF watt meter and see what they’re really generating as far as output, and how much loss they’re counting on in the antenna. 

Tim in Bovey

[Rich Total posts : 0]

… There is no access to RF ground, and in fact the “Reverse SMA” connector on the WH 3.0 is listerally just a 1/4 x 36 bolt with no center conductor at all and the use of this bolt is certainly no way to prevent ssomeone from connecting whatever the heck they want to this output terminal….

No matter how simple/cheap the transmitter or how complex/expensive, the antenna system it uses is subject to the laws of physics in order to produce e-m radiation.

Those laws show that useful power cannot be delivered across an open circuit.

For a simple proof of this, disconnect one terminal of your car battery, and see if you can start your car.

For a test needing less effort, turn off a ceiling light in your house or apartment using its wall switch or dimmer, and note what happens.

In the case of these transmitters used for Part 15 FM, the return path needed for e-m radiation is provided by some combination of the d-c circuit “common” return trace on the transmitter board, and the radiating cable(s) used as the progam source connected to that transmitter.

[Mark Total posts : 0]

On the Decade CM-10 the ground can be located by removing the top of the case and you will see how the telescoping antenna is connected to the board. You’ll see the centre connection to the swivel for the antenna and right beside is the ground where the BNC board mount used to be…also the two posts that the antenna assembly is mounted is also ground. The aluminium case is ground if you scrape a tiny bit of black anodised coating off. Also anywhere you see the silver tracing on circuit board along left side is circuit board ground.

With the Wholehouse the threaded reversed SMA is only + not ground….you have to open and find on circuit board or the negative battery connection should be circuit board ground.

 

Mark

[Rich Total posts : 0]

… With the Wholehouse the threaded reversed SMA is only + not ground …

Just to note that a-c (r-f) signals are not conveyed using two terminals/conductors where one of them always has a positive voltage.

That characteristic applies only to d-c circuits.

[Carl Blare Total posts : 0]

Regarding the RF ground of certified RF transmitters, Rich said: “In the case of these transmitters used for Part 15 FM, the return path needed for e-m radiation is provided by some combination of the d-c circuit “common” return trace on the transmitter board, and the radiating cable(s) used as the progam source connected to that transmitter.”

Having the circuit diagram for the C.Crane FM1 Transmitter I see that the audio shield and the power lines have inductors in-line which I suspect inhibits RF flow and avoids radiation from power or audio cables, and also discourages attachment of a negative antenna element.

I would expect to find similar filtering in all part 15 transmitters, unless physically found otherwise.

[Carl Blare Total posts : 0]

I’ve thought about it, and here is what I believe is true about the RF ground path of the certified part 15 FM transmitters.

Half of what Rich said is true: “the return path needed for e-m radiation is provided by the d-c circuit “common” return trace on the transmitter board.”

The few inches of the circuit card carrying the negative trace of the circuit is the RF counterpoise.

[Mark Total posts : 0]

Yes I’m aware of the difference between A/C signals and + & – with DC……just couldn’t find the term to decribe what I was explaining so I just said +. I think Timinbovey knew what I was referring to.

Mark

[Carl Blare Total posts : 0]

Yes, TheLegacy, the Wholehouse 2.0 is a spectral mess and that’s why I took it out of daily service. It makes a “better than nothing” backup, and eventually I’ll sell it.

Mark, you have told me more than I knew before about what the secret switch does, but I still want to see it… maybe a pot could be put in there to do what TheLegacy is talking about.

The C.Crane Transmitters have internal pots to back-down from “legal.”

[Thelegacy Total posts : 0]

In his duplicity our good buddy Carmine5 is giving advice for us but posting it at hobbycaster, referring to us as “the good folks on the other site.”

He thinks we should forget FM and petition the FCC to open up other bands.

 

Really?  Just what other bands shall we open?  And who would listen?  Now I’m all for getting rid of the ground rule for AM even if they keep it to 100mW.  But really I’d like to see 1 Watt.  AM needs to have a breath of freshness and part 15 hobby Radio could save it.  At least part 15 operators won’t be afraid to experiment with music on AM Stereo.  Maybe awareness will get more AM Stereo receivers available to the public.  Along with more power we need to get the FCC to have higher standards for phone chargers and the power supply that powers laptops and other things.  Once this has been fixed we can expect more possibilities for AM Radio and part 15.

[macdev Total posts : 0]

I saw that post too and just shook my head. His logic about the scarcity of FM radios *40 years ago* was silly.

No, we’re going to march on and get something accomplished.

[Carl Blare Total posts : 0]

Tracking down the FCC ID numbers I have obtained the shematic diagrams for the C.Crane FM2 and Scosche FMT4R.

Unfortunately the diagram for Wholehouse 2.0 is not posted due to a “Confidentiality Request” filed by the manufacturer. I wanted to see what the secret switch actually does in the circuit.

The diagram for C.Crane FM2 is much different than the older FM1. One observation is that the diagram for FM1 is so complex it’s difficult to study, and the diagram for FM2 is simplified shorthand making it difficult to reconstruct for lack of detail.

The Scosche diagram is not overwhelmingly complex.

I’ll eventually get these linked at

http://kdxradio.com/am.html

Maybe within a week.

[Thelegacy Total posts : 0]

Since the Scoche FM 4R is not made anymore it would be cool to make one that runs on electric and battery.  The little transmitter could be nice and cheap to build too.  Maybe add 75 uS pre emphasis to it and you’d have a nice little transmitter.

[Carl Blare Total posts : 0]

The Scosche already has 75 uS Pre Emphasis.

It sounds beautiful.

It does NOT have audio level controls, but they could be added.

[Thelegacy Total posts : 0]

Use a nice virtual compressor for your Audio like NextKast has or Breakaway Broadcast.  I wonder what the modulation percentage is before it limits it.  Hopefully not too high and not too low like 15-25% either.

[Carl Blare Total posts : 0]

Today KDX-FM put into service a second C.Crane FM Transmitter, giving us two side-by-side channels, one for the main program stream and the other for editing and auditioning.

The Wholehouse 2.0 has been closed and will undergo deep surgery in an attempt to draw a map of the innards to figure out what that secret switch does.

Once it’s put back together the Wholehouse 2.0 will serve as a backup.

[Thelegacy Total posts : 0]

Carl was that you that said that the Whole House FM Transmitter 2.0 was a spectoral nightmare with the spurs its generating?  It seems to me I read that somewhere.

[Mark Total posts : 0]

Carl, it’s very simple what the switch does…..it’s a high-low power switch switching  between two resistors controlling the gain of the final. It’s a switch instead of a continuous power out adjust with a potentiometer.

Mark

[Thelegacy Total posts : 0]

Too bad it don’t have a variable from 0-Legal.  As I’ve said before there are times you don’t want to transmit to the neighborhood especially if your just transmitting to your stereo accross the room or your home theater system playing the audio of a movie or meeting or just trying to tune the Audio for when your ready to go Live.  That is when things could be interesting if you could adjust from those levels.  I suppose he maybe on the same page as I am in trying to construct a variable from 0-Legal.

[Thelegacy Total posts : 0]

Again just so there is no misunderstanding of what I am trying to say. Nothing illegal simply saying to make the power level from 0-the value of the low power Legal USA setting. Since your not increasing the RF output to the final only decreasing it at times when you don’t want or need to transmit to the houses next to you. Just felt the need to clarify this attempt. Thanks

 

Best Regards.

[Carl Blare Total posts : 0]

I agree TheLegacy!

It has been said by persons in the know that some certified transmitters might be set low. If that is true, we have a legal right to “trim” the setting to get on the exact dot.

Or, we have the right to lower power to the level where it does what is needed, which is neat housekeeping.

Let there be no suspicion about it.

[MrBruce Total posts : 0]

If it was me, I’d replace any single pole double throw switch with a varible potentiometer.

Yes I am sure we are talking about making the certiication void, but still, working on CB radios all through the years, the output stages always used varible potentiometers to adjust the pre stages and final stages. I believe this can also be done to make sure a unit complies, not to exceed the final output stage legal limit.

Also, some transmitters did not come with any potentiometers for audio input adjustment, I believe adding those should not void the certification either, but I am not the FCC.

Please excuse typos, Windows 10 does not support browser spell check software plugins for IE or Edge.

Bruce.

[Carl Blare Total posts : 0]

I operate two C.Crane FM Transmitters, Models FM1 & FM2.

FM 2 sits atop the computer tower so the computer case acts as a ground plane, but FM1 sets atop a wooden shelf right behiond the computer.

An idea popped into my brain… put a CD disc under FM1 to give it something of a ground plane.

Zingo! The field reading on the spectrum analyzer increased +3 dBu.

[Thelegacy Total posts : 0]

I didn’t think of that one Carl. CD and aluminum inside the disc might make for a good capacitor. Pretty good idea. The things you learn just playing around with these transmitters.

[Carl Blare Total posts : 0]

Turned off everything but the Wholehouse 2.0 which I set at 101.5 MHz with a 440Hz tone at less than 50% modulation. The spectrum analyzer shows 30 dBu.

It seems the worse spurious noise is spread across the low FM band from 87.5 to 90.1 MHz, with all of it being very low level according to the spectrum analyzer except 89.5 and 90.1.

89.5 had a very small bump on the spectrum analyzer, well below the required 20 dB attenuation.

The signal at 90.1, however, was almost as good as the main carrier, at 21 dBu (only 9 dB down), which should have invalidated certification.

Below the FM band there were a few spurs from 77 MHz to 86 MHz, but they were all in the low noise region.

Above the FM band there were one or two very supressed traces of the tone with no reading above noise.

It will be very interesting to learn what Tim finds with the Wholehouse 3.0.

[Thelegacy Total posts : 0]

If I had a Patomac I’d find out what exactly 250 uV/M @ 3 meters will do.  We sort of know what 1,000 uV/M @ 3 meters will do because supposedly Decade sets their transmitters by hand (We’ll Not know this till someone has a Patomac and does this).  This is an expensive way to find out.  Unless one of us wants to start their own transmitter company lol.  This too has been my point in all my rants.  Its all speculation till we know what it will do.  And it seems even if one tests with a Pagomac FIM 71 there will still be questions as the the value of your results.  Rather yours is 100% equal to the FCC’s measurements.  There is so much we’d have to show in data and end the end the FCC can still hand out a NOUO if they feel you are over the limit.  Seems FM is going to always be a gray area in any sense.

[Thelegacy Total posts : 0]

11.4 Mhz.  There was an article on one of the I hate to say it “Pirate Radio” sites.  Agan I was searching for “Harmonics”+”CZH” or “Harmonics”+”FM Transmitter” and found peole talking about the CZH Transmitters and Chinese transmitters being junk because of the 11.4 Mhz harmonics.  Now studying what happened with my SainSonic AX-05B (Modified CZH 05B) at 87.9 Mhz – 11.4 Mhz is 76.5 Mhz.  This would have been around Channel 5 with the strongest spur.  Now its interesting to note that I’m using an older TV and the TV is tuned to channel 3 which the RF from the cable box transmits on.  Now keep in mind that the Whole House FM Transmitter is made from Richfield electronics.  Indeed doing my research its from China.  So my question is do all transmitters comming into the USA from China do this as was talked about on HB as well as Pirate Radio sites?  I thought maybe it was a myth that all chinese transmitters would do this. I thought that one model may do it where as the next won’t.  Turns out somehow they are getting their transmitters into this country forgetting about these spurs.  Here again shows why more strength on FM won’t work for too many transmitters are not actually made in the USA only C. Crane and I dont know about Scoche.  No wonder you see NOUO’s for just a little over.  Someone’s TV is being killed in the low end by these FM transmitters.  Again not a good rap for FM hobby Radio.  Why such cheap trash?  It should never be this way.  I may complain to SainSonic and demand my money back if I can prove this.  Or get them to fix the transmitter or send me a filter that blocks this at their expense.  Just one time I fond someone in my area with a spectrum analyzer and I’m gonna pust it on youtube for all to see.  They won’t want that I’m sure but the people must know by solid proof if this is what is happening.  11.4 Mhz almost as good as your main intended frequency is no way to do business selling transmitters.

[Carl Blare Total posts : 0]

Last I knew the C.Crane FM transmitters are made by Sangean.

I’ll check them for spurs, but I think they’re clean.

[Carl Blare Total posts : 0]

Earlier I described a problem and solution to multipath interference caused to FM radio when transmitting inside the house.

At the start, most people set their home transmitter for vertical antenna operation, then discover that as doors are opened and people move about, radios go in and out of tune, giving annoying bursts of multipath noise.

In previous posts I shared the first solution I found for about 90% or more of the multipathing, namely, a Mid-Fed L Antenna taped to the wall, the intellectual property of Carl Blare, shared with members of ALPB and part15(dot)us.

While installing a second C.Crane FM Transmitter I’ve happened upon an even simpler solution to the indoor multipathing problem.

Set the FM transmitter within a few inches of a wall, swivel the antenna into a horizontal position facing away from the transmitter, tilt the transmitter so the tip of the antenna touches the wall, set a surplus CD (disc) under the transmitter as a ground plane (unless you already have a metal surface).

Give it the multipath test by tuning a radio in another room to your frequency and walking about the house. For me, reception is solid without multipath.

[Thelegacy Total posts : 0]

I wonder if that would help that as its a metal transmitter already.  And unlike the C. Crane this transmitter at low power seems to be receivable further if you place your Radio near anything that is pluged in.  I even noticed in the laundry room that if I place the Radio on top of the washing machine I got better reception of my station at low power.  I wonder what would have happened if there was a close outside outlet on the porch?  It probably would have been heard in full Stereo and without any noise there as well. Someone (I think it could have been Bruce) mentioned that his Decade MS-100 did the same effect and seemed to transmit along the main power of the house or apartment making it nice and clear no matter where they were in the building so long as they had a pluged in FM Radio.  This could prove interesting too.  If you modify the Scoche for electric operation would it too follow the power lines like my SainSonic and the Decade does?

[Carl Blare Total posts : 0]

As reported, I am now using two C. Crane FM Transmitters on side-by-side frequencies.

In the published reviews on the two versions, FM1 and FM2, the main improvement in FM2 is reduction of a noticable hum on the FM1. I can verify that this is correct.

When FM1 is operated with full modulation, the noise is far enough in the background to become unnoticable, for which reason I transmit KDX Main Channel Programming on the FM1.

FM2, with the cleaner background, is assigned to editing and auditing chores as well as audio for Youtube, HULU, and listening to WCFI.

As time advances, I have the question of whether the hum in the FM1 can somehow be reduced, and will be on alert for anyone who reports their experience.

[Carl Blare Total posts : 0]

As planned, the Wholehouse 2.0 got popped open for inspection.

The front half of the plastic case is snapped to the adjoining half by small plastic clips, 3 out of 4 of which broke off.

The circuit board is held by 3 tiny screws which came free with a jeweler’s scredriver, allowing the card to be removed and viewed from all angles.

Aside from a few multi-contact chips the component parts are very tiny and all look alike, leaving me unable to distinquish between resistors, capacitors, inductors, or what-notters.

Only one chip contained an almost readable marking, the others were blank.

Trying to map out a circuit seemed un-doable, so I re-assembled it and will ban the name “Wholehouse” from the entire house.

Part 15 FM is a shabby business.

[Carl Blare Total posts : 0]

In light of Tim’s findings about inter-connecting cables radiating and so causing increased RF field strength in his testing of Wholehouse 3.0, I set up this morning to analyze the two versions of the C.Crane FM transmitter with and without cables attached.

Placing each transmitter in the top center of a 30″ stool located 12′ from the spectrum analyzer on a 30′ high desk, the first test was with fresh batteries and no external cables connected. It should be mentioned that these transmitters have an attached audio cable which is coiled to a length of 18″ and can be stretched to a reach of 5′. I had this coiled into a small bundle set alonside the transmitter. Antenna was horizontal pointed away from the transmitter with the broadside toward the spectrum analyzer, whose antenna was likewise horizontal broadside toward transmitter.

The second test for each unit was AC powered with the 5.5′ wall wart supplied with the transmitters.

Third test was connected to computer audio output 1.5′ from transmitter.

RESULTS:

C.Crane FM1

41 dBu with batteries only

52 dBu with AC power

59 dBu with audio connected.

C.Crane FM 2

56 dBu with batteries only

58 dBu with AC power

61 dBu with audio connected.

After completing the above measurements I realized the stool is metal, the surface being a round sheet of flat cork. Point being, the stool no doubt provided a decent ground plane which most likely raised all readings by some equal amount.

The Specifications for FM2 instruct, under Audio Input Cord: “Extention cords are not recommended”. There is no explanation given.

What we learned: connected wires and cables slightly increase the output strength.

 

[Ken Norris Total posts : 0]

I may have missed the post (many on this topic), but, in the end, with certification and education institute experimentation aside, there is just one criteria for the legal use of FCC Title 47 Part 15 FM as used by the public, which is spelled out in 15.239 (the 200 kHz refers to bandWIDTH in subparagraph a):

“(b) The field strength of any emissions within the permitted 200 kHz band shall not exceed 250 microvolts/meter at 3 meters. The emission limit in this paragraph is based on measurement instrumentation employing an average detector. The provisions in §15.35 for limiting peak emissions apply.”

Having said that, there is also a very general guideline of clear transmissions of 200 ft for Part 15 radio, although the rules themselves take precedence. Part 15 AM as we know, can get out much further depending on other criteria besides field strength, but for us, FS is the only true criteria for Part 15 FM. 

This means, although antenna loading and ground conductivity do have an effect on any radio transmission, you could still have other circumstances for a “FCC Certified” transmitter which could either push the intentional radiated signal beyond legal FS

[Carl Blare Total posts : 0]

Hi Ken Norris, glad to hear from you I love the “Walkie Talkie Show.”

What Tim’s field measurements of the Wholehouse 3.0 certified transmitter and now my simpler tests with both versions of C.Crane FM Transmitters has demonstrated is that ownership of a certified part 15 FM transmitter is no guarantee whatsoever that we are complying with 15.239.

That leaves us with NO WAY of checking our own compliance, since we obviously don’t have the expensive measurement equipment.

The “200 foot rule” is way to unofficial to be a reliable guide, and it is subject to different results with different radios.

[Thelegacy Total posts : 0]

Something I brought up Carl when I first started the initiative for more power on FM.  It was why I wanted to ask for 500mW, 800mW on Rubber Duck antenna.  This is something tangible.  Something the avarage Joe can wrap his head around.  Field strength is NO WAY for a common person to even begin to make sure he or she complies even with a Certified FM Transmitter.  The Rules for AM as in 15:219 is 100mW into a Antenna/Ground combo not to exceed 3 meters in length.  Now that we can wrap our heads around.  So in a sense the FCC has set all part 15 operators up for failure to comply with the rules.  This way someone can complain about you taking away listeners and the almighty NOUO to come afterwards.  So this is why we need to get the FCC to throw away the idea of field strength and allow more power maybe just under a watt into an inside antenna.  That again you can wrap your head around and also gives FM some usefullness as far as personal broadcasting or short distance neighborhood broadcasting.

[Carl Blare Total posts : 0]

The comment just made by TheLegacy is the ONLY approach that makes sense!

Dear FCC;

Your cavalier gentrified jab joke called 15.239 is played out. It’s gotten old. By now lunchtime drinks have worn off and you can lower yourselves to serve the (ugh) public.

SincerelyPart 15 Hobbyists of the Homeland

[Rich Total posts : 0]

The comment just made by TheLegacy is the ONLY approach that makes sense! etc etc

IMO, the clip above is based much more on emotion, than science.

Can anyone (including the author of the above clip) show/prove why that clip is true, in this context?

[ArtisanRadio Total posts : 0]

If you know the power, and the antenna characteristics, along with the receiver sensivity, you can calculate the approximate range.  That will give you the potential for interference.  You did that yourself, Rich, when you did those NEC plots.

I don’t believe that 1 watt, or anything close to that, will fly.  With one watt and a good, elevated, outside antenna (how are you going to regulate that the antenna be inside, and just what exactly does that mean), you can get miles of coverage (as evidenced by unlicensed New Zealand broadcasters).

I don’t think that you can hope to get much more than making Part 15 FM equivalent to Part 15 AM (and likely not that either, with interference concerns) – so for the best antenna, with the best receiver, you would maybe get up to a mile range.  Much less with typical antennas and receivers – Part 15 AM transmitters typically get 1/4 to 1/2 mile.  I don’t know what kind of power that would work out to, but it can be approximated.

If we assume a field strength at 5280 feet (approx 1 mile) of 2.5uv, that works out to a field strength of 4400uv/m at 3 meters.  That then works out to be about 200 nanowatts – so take it up to 1 microwatt to allow for all sorts of inefficiencies and the other factors that seem to affect low power FM signals so much.  I wonder what a NEC plot would say about the 2.5uv contour for a microwatt of power, and a dipole antenna (say, installed at a 10 meter height).  That would give you pretty much the maximum possible range for such a transmitter.

[Rich Total posts : 0]

… If we assume a field strength at 5280 feet (approx 1 mile) of 2.5uv, that works out to a field strength of 4400uv/m at 3 meters. …

Note that a field intensity of 2.5 µV/m arriving at the receive antenna of most FM receive systems would not provide a very useful output for the users of those receive systems — especially for analog or digital FM stereo transmissions.

Also note that your statements in the clip above apparently are based on free-space path loss, which does not apply for transmission paths near the earth.

[ArtisanRadio Total posts : 0]

I agree – that’s why I bumped up the power.  2.5uv is the absolute minimum that you can receive a signal with on a car radio with a sensitivity of 1uv (or possibly under).  I chose it because the FCC won’t care about the typical user and range – they’ll want to know the maximum range and the possibilities of interference.

[Thelegacy Total posts : 0]

Here is what we do know. As I have talked to Brian we know that the Whole House FM Transmitter is just under 100mW at its low power (Out of the box) setting. We also know that the field strength at 3 meters with cables plugged into this unit is 1775 uV/m at 3 meters. This is far above the strength of 1000 uV/m at 3 meters for Canada. With this in mind it would not be hard to ask for a multiplier of 2-3 times that strength which is 3550 for twice the power and if you want 4 times that you get 7100. This would get you close to a 500mW transmitter into a rubber duck (Same as the Whole House 3.0 or Sainsonic AX-05B). To further test my theory of someone has a Patomac FIM-71 and tests the SainSonic AX-05B or FailSafe CZH-05B transmitter at its 500mW setting I am sure you will come up with this reading onto a Rubber Duck antenna (The one SOLD with this unit). If the law sated Any use of any other antenna is in violation of the rules and made 500mW the legal limit I don’t see what Rocket science it would take to understand this. We have the Data for a Rubber Duck. So talking about a di pole, Ground Plane, Beam or any other antenna except Rubber Duck and 500mW is irreverent at this point. Now after we have the tests for a telescoping antenna at 100mW we can compare that as well. SainSonic does sell a telescoping antenna that is suppose to go with their 7 Watt transmitter. However you can buy the antenna separately. What we would have to do is test that field strength assuming the TNC connector is the same as the TNC for the rubber duck. Something tells me that the strength would quadruple for the telescoping antenna. There is also a Signsteck CZE-T200 transmitter which has a Rubber Duck and 4 power levels that we can test for field strength. It is not certified but would also prove my theory because it has 4 levels and 4 ranges in reception to a car Radio. 1MW (10 ft), 10mW (150 Ft), 100 mW (¼ mile), 200 mW (½ Mile). This was to a Car Radio. If we test the field and range we have the exact proof on a Rubber Duck antenna to present to the FCC. The already illegal strength the Whole House puts out has not made planes fall from the sky, Ambalances miss their patients, Police to miss their dispatches, Public Safety has not been harmed, and life continu3ed as normal. So though you have organizations with the Chicken Little syndrome we have data to prove otherwise. We know SainSonic’s output, FailSafe’s output and Signsteck CZE-200’s output and we will say Whole House’s output at 100mW. All have Rubber Duck antennas so lets start with that for forging the new rules for FM. Put up an outside antenna – GO TO JAIL!!! That is it for FM.

[Carl Blare Total posts : 0]

In August the computer that operates KDX Worldround Radio froze solid three times, having never done so before.

During the same period I’d been conducting transmitter/antenna tests with two C.Crane FM transmitters in close proximity to the computer, and wonder if that was causing the freezes.

Since September 1 the transmitters have been moved to a distance and no compter crashes have happened, so things are looking good for naming the RF from the transmitters as being potentially hazardess to computers at close range.

Please report your experiences of this kind.

[Carl Blare Total posts : 0]

The computer “freeze” problem has continued to occur at random, and Youtube has a few videos about the “XP freeze problem,” but the main point is, it wasn’t being caused by the proximity of the C.Crane FM transmitters.

In signal-level tests with the spectrum analyzer, I previously reported gaining a little output by placing a CD disc under the C.Crane FM Transmitter, giving a kind of capacitance-coupled ground-plane.

Which brought the thought… perhaps if the RF output of Part 15 FM transmitters was higher than allowed under 15.239, the radiation might start to interfere with nearby computer components, since many people place their transmitters on top of or alongside computers.

Then I realized, a ground plane is only good for vertical polarization, but I find that horizontal works better indoors. Instead of a “virtual ground,” placing metal under the transmitter, perhaps we can come up with a “virtual di-pole” by placing wire or a CD on the side of the transmitter facing away from the antenna ??

[Carl Blare Total posts : 0]

There are two main changes in the C,Crane FM Transmitter 2 compared to the earlier C.Crane FM 1.

Several published reviews have noted that a detectable noise floor can be heard in the FM1 when listening closely to the carrier, which is gone from the FM2.

And while FM1 has a single red LED that flickers to display overmodulated sound, the FM2 has 2 LEDs, the green lights during average audio and the red showing overmodulation.

Other than those two differences, the two transmitters sound exactly alike and have the same range.

Using Stereo Tool or any good processor for raising the average audio level, the modulation heard from an FM1 is excellent and the audio will conceal the relatively low level of the noise floor.

Doing A/B comparison, FM1 on 89.5 MHz driven by Stereo Tool and FM2 at 89.9 MHz carrying unprocessed audio, the FM1 sounds stronger and more dominant due to the diffence in audio handling.

The conclusion shows that the C.Crane FM1 remains a viable and useable transmitter and there is good reason to own one if it comes at a good price.

 

[Mark Total posts : 0]

There’s pro’s and con’s to everything….every idea has a negative and positive. Key is to find a middle ground that works for all involved.

Rich, even you have to admit the FM rules in the USA are a “little” to restrictive and a slight relaxation in the allowed field strength won’t cause any interference that would be a problem as long as the transmitters are clean.

Mark

[Carl Blare Total posts : 0]

We are at an impasse based on what Tim has demonstrated.

His field tests find conclusively that a certified FM transmitter produces significantly more power than 15.239 allows, with added strength caused by connecting cables.

I have run tests on two other certified transmitters, FM 1 & FM2 from C.Crane, and found that connecting cables increase the field strength output as does the addition of a metal surface (ground plane) under the transmitter.

Because certification does not guarantee compliance for the end user, we are left with no means whatsoever to assure compliance with 15.239.

Take this further… if we can’t determine the present field strength as allowed by 15.239, we will also be unable to calculate any higher field strength, if allowed.

Nothing is gained by talking about anything but this basic point.

[Rich Total posts : 0]

… it was why I wanted to ask for 500mW, 800mW on Rubber Duck antenna.  This is something tangible.  Something the avarage Joe can wrap his head around.  Field strength is NO WAY for a common person to even begin to make sure he or she complies even with a Certified FM Transmitter.  …

Radiated field strength at a given distance is the most logical measure/limit for the interference potential of unlicensed setups legally permitted by Part 15.  Interference potential is the main concern of the FCC and licensed broadcast stations.

Permitting “500mW, 800mW on Rubber Duck antenna” does not define the field strengths such systems can generate at a given distance — when considering the radiation that can be produced by the program, power, and “ground” leads connected to that FM transmitter (FCC-certified, or not).

Tim in Bovey documented this very well by his field intensity measurements of an apparently FCC-certified Part 15 FM transmitter while using two different, calibrated FI meters — which FI readings supported each other.  NEC software evaluations of those systems produce the same conclusions.

The FCC has documented the same for the effects of such conductors attached to AM transmitters, as stated in NOUO citations issued by the FCC to operators using such configurations — and by Internet comments that those operators were using AM transmitters having Part 15 certification.

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