Oh, and I wouldn't be afraid to ask questions at all.
Most of us here, even those who have been doing this for some time, recognize that we all have a lot more to learn. And I haven't seen anyone yet discourage someone who wants to enter into this hobby.
I think what bugs people the most is those who think that they know it all, and proceed to tell everyone that no matter what the subject at hand, when it's pretty obvious that they don't.
I would like to know where the documentation is on the certification setup to the TH/iAM/ATU system.
Was it certified with the external ATU sitting on a table at 1 meter off the ground plane, or hoisted up on a pole.
This thing was marketed for real estate sales, meaning 99.9 percent chance no typical house being sold and featured on the radio is going to have a 20 foot or taller pole handy to mount the ATU, and I doubt too many real estate agents would climb up on a ladder to mount this ATU.
It was meant to be mounted on the for sale sign, at most a few feet off the ground. The long coax allows for the ATU mounted on the sign to be out in the front yard as far as possible towards the street to get the signal up and down the road.
Point here is that just because there is so much coax that comes with it, I would want to find out for sure what height that ATU was sitting at when the entire mess was certified.
RFB
The InfoSpot system is built around the IAM/Talking House transmitter and ATU.
They specifically advertise the system as legal under Part 15 rules, placing the ATU (antenna) up that pole with up to 300 feet of coax.
They imply the legality (FCC acceptance) of this with their advertisement. Please view INFOSPOT SYSTEM information.
It would be much more comforting to view what RFB is referring to, the actual test setup.
If the system is installed as advertised and failed to pass an inspection, well I'd want a refund.
Also, it seems to me, that because the ATU on 300' of coax is such a total departure from the rules, assuming it is truly approved and certified, shouldn't there be a "trickle down" effect where the method becomes generally available under 15.219?
I really would like to have the advantage of a transmission line so transmitters could be in a common room and the antennas located out there in various locations.
Get the NALPB to work on this.
Well When I contacted Radio Systems for a quote on a complete iAM and ATU package, the quote specified that a 100 foot long coax was included.
So wishing to know more, I went to the RS/iAM website.
Tried to find this 300 foot long coax for the TH/iAM/ATU systems.
I cannot find this 300 foot long coax offered anywhere on the TH/iAM/ATU website. Only the 100 foot long coax.
So is the other company correct in stating that the TH/iAM/ATU units are in fact certified to use that 300 foot long coax, regardless if it's up on a pole or 300 feet away ground level?
I just get this feeling that the TH/iAM/ATU systems were not certified with 300 feet of coax sitting up as high as it can go with that 300 feet of coax.
I do not think it was even certified to have the ATU as high as it can go with 100 feet of coax either.
I think it was certified to use that 100 feet of coax to the ATU with it mounted in the standard test configuration of 1 meter off the ground plane in the test chamber.
And if some thought on this were expanded, the typical real estate for sale sign post is right about 1 meter or slightly taller.
Yep, that actual certification documentation should be available to the public, if not by the FCC, then by Radio Systems themselves. It's not necessary to show any company secret information, but I believe it IS necessary to see exactly how the TH/iAM/ATU combination was tested for being granted an FCC certification to comply with Part 15.219.
The ATU's internal toroid transformer, and the coax, all use the same ground, which is the same ground stub on the outside of the cabinet. When connected, your coax ground is now at the same continuity as the ground lead of the stud connecting to the mounting structure or wire ran down to the ground system.
This means that the return path for RF is now not only on the mounting pole and ground system, but along that coax too.
So I want to see the documentation of how these were certified before I purchased one, or at least go to the extent of putting the ATU up on even a short 10 foot pole if the coax becomes a part of the antenna's return path because the grounds are all of the same continuity.
RFB
I have emailed William Baker at "The Radio Source".
I have requested information regarding FCC acceptance of the InfoSpot system specifically regarding ATU (antenna) installation.
Standby for further details...
300 feet seems like a long run even at 1.6 Mhz, anyway to get rid of hum on my talking house installation I use a gel cell battery, and charge when not transmitting, that completly isolates the transmitter from the power lines. Some how the RF gets intangled and modulated into the 60 HZ in the power lines and its a mess.
Using a standard talking house with the plug in power supply, I always get the buzz, then when the refigrator comes on or wash machine starts or a light goes on or off, the hum would change in intensisty or id have to turn the radio this way or that way to null it out. I finally went to and out side vertical antenna and fed with coax, along with running direct DC got rid of the hum period.
I also need to say you ground everything to the same point, the transmitter, the audio chain the audio source ground it all. I did also have to use ground look isolators just about every where but that is insantiy but it seems to work. Some times it made the hum worse.
I also found that running a ground directly to the coax terminal when using an outside antenna helps, ground it there and ground it at the ATU if your using one. I use a loading coil but have the coax grounded at the loading coil end also.
On the voltatge, I did several tests, at 12 volts the oscilliator some times wont operate at the frequency the display shows, then when I increased voltage to 13 or so, then it locked, the RF output once past 12 volst does not change so the RF output has a voltage regulator in the chain some place. I run mine at 18 volts like the sticker says.
I use two 12 volt batteries and then a variable voltage regulator set to 18 volts for the transmitter.
Thats all I know, I would vist more but I have a yard to broadcast to out there - sorry for any mispelling, you get old you forget-
Radio Joe
" the RF output once past 12 volst does not change so the RF output has a voltage regulator in the chain some place."
Not the case. There is no voltage regulator feeding the final's B+ supply or the current amplifier (modulator). The 18 volts is directly fed to the modulator transistor collector, emitter feeds modulated B+ to the finals, npn and pnp pair.
The two stages before the finals run off a regulated voltage from the 18 volt main, and operate at 12vdc. Since these driver stages are fed a regulated B+ of 12 volts, it wont matter what voltage you increase on the input, those drivers will always see 12 volts B+ from the 12vdc regulator on the left side of the unit where the heat sink is.
And this is why when you dropped voltage below 12 volts, the 5 volt regulator, which gets its B+ from the 12 volt regulated rail, won't produce enough voltage to run the PLL, the oscillator, and even mess with the microprocessor.
A member here (kc8gpd) was able to obtain the real schematics to the TH unit which also shows the factory modifications which are hand drawn onto the existing circuit paths and components.
An isolation transformer at the audio input will eliminate any hum loop problems.
RFB
One thing I noticed is that in none of the example photos do they show any infospot unit in operation, or mounted anywhere in the picture frames.
Also, on the specs, it states "UP TO 300' - 25 recommended".
So there it is, in plain text. Nothing there is saying that unit is actually certified for 300 feet of coax or it's ATU certified to be mounted 300 feet up, or even 25.
Can't wait to see their info!
RFB
Let go of the Argument fellas . It's really very simple , Just work on your
station and put that Antenna where it works best.
Should the FCC Not like it then make the necessary changes.
The Law is vague at best , so do what you think is right and then stand up for you're self and make the Inspector work for a living.
Use your brain and make the inspector use his.
Then at the end of the day if you need to make the changes to get the station back into spec.
Arguing ain't getting anything done.
I did receive a reply from an individual at Radio Source by way of Information Station Specialists (ISS.)
This person, who will remain nameless until given permission to devulge their name, avoided the question regarding acceptance testing.
Rather, they stated the "system" includes the ATU which is viewed by the FCC as the final RF stage when used. He further states the ATU may be placed any distance from the transmitter and the length of the coax is not considered as part of the total antenna length (read antenna, lead-in and ground wire.) I am pressing for clarification of this.
On the other hand ISS states the InfoSpot ATU is mounted inside an enclosure and to maintain the 3 meter antenna rule no separate ground wire shall be connected to the ground lug of the ATU using an 8 foot whip antenna.
Both individuals indicate the length of the coax has no bearing on the total antenna length as far as the FCC is concerned.
Here is a PDF Product Slick that has a better view of the InfoSpot transmitter cabinet and ATU cabinet mounted on a pole. It clearly appears the ATU is at least 25 or 30 feet above the transmitter cabinet.
Further details as received...
The advertisement for the Info Spot has a few stand out claims...
100mW Output ......
Most well known and best designed transmitter....
Sounds like a siding sales pitch.
Keep the mystery train on the tracks.
Next stop... ahead!
"Arguing ain't getting anything done."
I'm not sure exactly where this "arguing" is taking place, but I don't see it in this discussion.
Information is being sought and observations made about certain claims of a product.
Just because there is a photo of it mounted up on a pole does not mean that photo is proving how it was certified. I'd rather see the actual submitted documentation, which would include photos of how the unit was set up.
If we see a photo of the ATU hanging high, wonderful! I will order one in a micro-flea-low nanosecond!
If however there is no photo showing this high in the sky, and only a photo of the ATU mounted on a short stub attached to a table that is 1 meter in height off the ground plane system in the testing chamber, or sitting on a stool in the middle of a field 1 meter off the ground, then I would think otherwise before tossing the ATU up on a flag pole, but would still consider a purchase, and request that they "fix" the wording in their information.
All I'm doing here is noting some very important and valid points that anyone should ask ahead of time instead of just flinging it into the wind and doing the 50/50 swing ding dance that an agent will simply say fix it or hand you a NOUO/NAL.
And IMO, any company making claims as to their unit being certified to install in such and such manner in where such install is obviously way outside of the "functionally compliant" rules had better back that up with OFFICIAL documentation to prove it, you know the one that is published by the OET that even has the fancy FCC seal which anyone knows, anything official when it comes to the original certification document or license, it has that infamous FCC seal.
Show us your seal....honk honk! :p
Do I do a good impression? 😉
RFB
I bought a ground loop isolator for $20 at radio shack and hooked it up between my mixer board and the line input going into the transmitter and the hum went completely away.--Bill
Garrett Conover of Radio Systems (read Talking House) informs me that, per the Talking House (I AM) Part 15 certification, the FCC considers the ATU as the Final Stage of the "system" and the coax has no bearing on the 3 meter antenna definition.
Futher, he gave permission to quote him regarding this:
Gerrett Conover <[email protected]>
08/17/2012 15:46
To "[email protected]" <[email protected]>
cc
bcc
Subject RE: InfoSpot
The coax has no bearing on the antenna length on the iAM transmitter/ATU. The final RF output is the RF connector for the antenna.
Gerrett
--------------------------------------------------
Gerrett H. A. Conover
Vice President, Radio Systems
601 Heron Drive
Logan Twp, NJ 08085
856-467-8000 Voice
856-467-3044 Fax
856-803-1060 Direct
On Aug 17, 2012, at 7:52 PM, "[email protected]" <[email protected]> wrote:
So, what you are saying is the FCC does not consider the coax shield as part of the ground connection to the ATU even though it is connected internally to the ATU grounding lug.
This satisfies many questions regarding the legality of mounting the ATU up on a pole whereas the coax shield is grounded through the transmitter chassi.
The ATU has been the subject of many forum debates regarding a long ground wire (read coax shield) connected to the ATU given the ambiguity of the Part 15.219 antenna requirements.
Thank you for the info and I will post this on the forums I frequent. May I quote you as the source of this information?
Reply:
Gerrett Conover "Yes. Sent from my iPad"