WSPR on 13 Mhz.

I would be beaconing from FN00cr at about 3 dBm into a quarter wave vertical antenna ...  Both power and frequency stability should be well within FCC compliance standards for this band.

Ambitious and interesting project, Jim.

Just to note that 2 mW (+3 dBm) radiated by a 1/4-wave, base-fed, vertical monopole with a very low-loss connection to r-f ground potentially could produce a maximum field exceeding 14,000 µV/m at a horizontal distance of 30 meters.  The legal limit at 30 meters permitted by FCC §15.225 is 10,000 µV/m.

That's not much over, and probably would not come to FCC attention, though.

Also -- that vertical antenna system probably will have loss in the connection to r-f ground, such as to a ground rod or buried radials.  If that loss reduced the radiated power to about 0.9 mW, then the field at 30 meters would just meet FCC §15.225.

Looking forward to reading about the results of your experiments.

This is an interesting project and I bring the good news that a more recent issue of FCC 15.225 shows...

(a) The field strength of any emissions within the band 13.553 - 13.567 MHz shall not exceed 15,848 microvolts/meter at 30 meters.

Earlier editions of the rules show 10,000 microvolts/meter, as Rich mentioned.

I Googled up an old FCC document, and would delete my previous post here except it is now too late.

Thanks Rich,

I've heard that the 13 Mhz. band is one place that RFID tags are allowed to radiate RF? I can't imaging what an FCC certification process would look like for an experimental WSPR transmitter feeding directly into a 17 foot vertical or groundplane? I wonder if they have ever certified such a beast? For one thing, field strength measured at 30 meters from such an antenna would be almost meaningless in terms of indicating what interference, if any, might be created after the first hop by sky-wave. I suppose they don't actually care about that and as long as you comply with limiting whatever is radiating from the antenna to under 14,000 µV/m at a horizontal distance of 30 meters you're good. Perhaps they did not anticipate that skip at that freqency could even be a factor? Anyway, I don't want to be the first to set the precedent for how they certify an RF device that can have any kind of antenna and feed line as long as its RF field strength remians under 14,000 µV/m. It sounds like an inappropriate and largely  meaningless test to me. But heck, I'm new here, so I'm willing to learn.

Having said that, I'm very curious as to how one without lab certified test equipment might set up and meaure field strength with such a setup to obtain some ballpark figures. What would I need? Just don't menion HP, because I can't afford it.

I was reading on his forum what some of the group were doing in this area back in 2000, or thereabouts, but I've found very little in the way of posts since that describe what others have done with regard to building and operating ultra low power beacons on 13 Mhz under Part-15. Perhaps I've missed something.

Many thanks,

Jim

Hi Carl,

Firstly, let me apologize if you did not receive my reply comments regarding my first post on the forum about the DC-38-10S. I was having trouble getting the system to accept my replies at the time - probably my confusion - and could not see any of my replies. It seems to work ok now. The unit is still sitting on my bench and after many inquiries I still have not sorted out any useful documentation or schematic. I think you said you might have something that could help, and if so, I would be very happy to pay costs to have it duplicated. The boards and wiring look pretty straight forward, but there are a million wires and connections and it might take me a long time to troubleshoot it without any doc. If I ever get it running again, I may loan it to our KDKA exhibit at the Saxonburg Museum, although it's not that vintage. Thanks

Thanks also for bringing me up to date on the FCC doc regarding field strength compliance for 13 Mhz.

(a) The field strength of any emissions within the band 13.553 - 13.567 MHz shall not exceed 15,848 microvolts/meter at 30 meters.

After reading comment here and elsewhere I was guessing that that would end up meaning that the maximum ERP in the case of a ground plane might lie somewhere between 2 and 4 mW, but it's still pretty fuzzy for me.

Again, my first task is to pick a frequency to beacon on within the band? Not that it would cause a great deal of harmonic interference, the transmitter would have adequate filtering in terms of a well engineered LPF.

After operating on the 30 and 20 meter ham bands over the past year, I have been greatly amazed at the distance that can be obtained with powers down to 1 mW into an isotropic radiator. I have noticed that on WSPRnet, there are a number of SWL stations reporting to the net from all over the world. I would hope that this could also be the case on the 13 Mhz. Part-15 band. I may be too optimistic, but I don't think so.

Thanks for your comments and for having me on this very interesting and stimulating Group and Forum.

Jim

Having said that, I'm very curious as to how one without lab certified test equipment might set up and meaure field strength with such a setup to obtain some ballpark figures. What would I need? Just don't menion HP, because I can't afford it.

I remember measuring for compliance a device below 30 MHZ though I can't remember the device specifically. The instumentation consisted of a calibrated Field Intensity Meter and a calibrated magnetic loop antenna.  Antenna correction factors + coax loss (negligable)+ observed FS = Real FS.  The measurement for this device was performed on an open area test site. (OATS)  The FIM was an Eaton though you could use a HP 🙂 Hope this helps.

Thanks John,

I wonder if this is what you are referring to? It's sure a nice looking piece of equipment. Toronto is usually pretty expensive, so perhaps there might be a chance to pick one up in the open market for less than $900. I'm sure it's worth it though.

http://www.torontosurplus.com/test-equipment/meters/specialized-function/eaton-nm-17-27a-emi-field-intensity-meter.html

Thanks very for the reply and the lead.

Jim

You might want to hook up with the

Long Wave Club Of America.  These

guys build lots of beacons, as I'm

sure you know.  They are the Lowfers,

and then there are the Midfers (just

below the AM broadcast band) the

medfers (just above the AM BCB) and the

Hifers at 13 MHz part 15.  Canada also has

an unlicensed allocation around 6 or 7 MHz,

but we do not in the U.S,, as I'm sure you

know.  There are a lot of unlicensed beacons

out there that are legal and have been running

for years. 

I built an AM transmitter for 13.560.  It was just

for fun, and local use.  It worked well, but would

never work with the digital modes. 

If you do this, you will do best when the maximum

usable frequency is just slightly higher than the

13 MHz band.  Then, I think, the ionosphere

should be a better mirror. 

I don't know must about F2 propagation, but

I have heard some great stories.  As I'm sure

you have read, around 1957 to 1958, 50 to 70

MHz was the place to be.  I think some of the

lower TV channels skipped thousands of miles

then.  Television broadcasting was still fairly new,

so there were not many stations on the air.  TV DX

was easier.  I know of a ham radio guy in Connecticut

in about 1958, who had a great contact.  On 6 meters

he worked a guy in California with a 1 watt AM 6 meter

transmitter.  (A Gonsett Communicator, or something

like that.)  His signal was very strong in California, and

his transmitting antenna was a dipole taped to his

basement ceiling!

Propagation study.  Great stuff.  If you can help

all of use solve the eternal mysteries of E-skip

let us know.  And let me know, too.  I have been

trying to predict E-skip for decades.  Oh, those lucky

guys who have made 222 MHz E-skip contacts.  Only

opens up for a minute of two, but is 60 over S9.  What

a thing to see.  (I haven't, I can only imagine.)

BACK to what you are doing - these new digital

modes that can dig signals out of 20 or 25 dB of

noise - well - it's mind boggling.  Whatever you

can do will contribute to the state of the propagation

art.

Best wishes, good luck and keep us posted.  Even those we

are "program broadcasters" here, a great many people will be interested.

Bruce

I found info about 13.555 Part 15 beacons

and then lost it.

It looks like there are at least 20 active 13.555 MHz

beacons, maybe more.  It's seems that they are 

using cw, QRSS, and WOLF.

I have bad eyes, hence, the loss of the web page,

but I will try to get it back. 

It's there, you just have to dig. 

By the way, it seems some guy got across

the Atlantic on 9 kHz.  Now, that's

really something!

Great stuff!

Bruce

It isn't even "Part 15" because,

officially, as far as I can tell, there

is sort of - well - no "radio" below 9 or 10 kHz. 

Of course, I know nothing about this except bits

and pieces.  It was not a contact, and no info

was transmitted.  It was just - is the carrier there -

or is it not there...  That's the way they went with

it, and I'm sure a lot of software was involved. 

Still, it's a miraculous achievement!  The guy

transmitting the signal was a ham - W4DEX -

I think he is in North Carolina, although I

could be wrong.  It looks as if the carrier was

received in the U.K.

Bruce

That would be the one.  $995 = 995 pounds also.

Thanks Bruce,

I remember that Gonset Communicator from the early 60s. By best friend had one and I thought it was one of the best looking rigs ever. I'm still looking around for one (the white one).

In the early 70s, I had a TenTec Argonaut and I could sit in my driveway in LA and talk to Japan and VK on 15 just about any summer night with its 5 watts.

About 10 years ago I was driving from Pittsuburgh to NYC listening to 10 meters on a very short mag mounted whip. The band opened up and I was able to work every continent but Africa (I heard SA though) in the space of about 2 hours. I was running 5 watts.

My best QRP contact, though, was between Egypt and JA a few years back when I was SU9AM in Cairo. I was running a Harris exciter putting out 200 mW into a curtain rod on 14.060. I worked two five watt JAs in a row and got both QSLs later.

When I did not have a license in Egypt I would SWL'd Longwave airport and port beacons. I had 36 countries heard, the furthest away being the Cape Verde Islands. I think that was the most radio fun I ever had, actually.

But now it's even better because I'm heard in Europe on WSPR running only 10 mW on 20. So that's why I love low power. You just never know what is going to happen.

Thanks for the tip on Long Wave Club of American - I will look them up.

PS - I was also listening on 10 meters in 1958 on my NC-98. The band was covered from one end to the other. Ah, the good old days.

Many thanks,

Jim

W3BH

Jim, first let me talk about the Ramko situation... I thought I read in one of your previous posts that you had located the needed Ramko documentation, so I stopped action on finding a SCSI cable to test my scanner.

HOWEVER, it appears that you would still like what I have to offer, and since I also would be well off reviving the scanner, I will GET ON THE STICK and get back to work!

Now over to 13MHz Part 15... the center frequency of 13.560 MHz was the focus of a project here at part.15.us in which a "committee" of us designed and built an AM transmitter for this frequency. Many members contributed design helps and the final result is published on my website:

http://www.kdxradio.com/bigtalker.html

WOW!  Great F skip stories!

I don't have much.  All of mine involved

listening.  I'm a ham, but didn't have transmitting

gear up and running at those times.

There were a couple of things.

For years, the BBC ran on 15.070 MHz -

their world service.  I'm sure you know

about that.  I was lucky to hear the second

harmonic on 30.140 MHz, on a Radio Shack

scanner with an indoor antenna.  (New Years Day, 1989.)

At a time when I had never ever listened between

30 and 50 MHz - i walked down to the local Radio Shack,

and bought a portable that received (among other things)

that range - 30 to 50.  Then home, I took it out of the box, pulled up

the antenna, plugged it in - turned it on - and 30 to 50 Mhz

was FLOODED with Spanish language transmissions.  (South or Central America?)

I was in Connecticut.  (I still am.)  I turned up to the top (50 MHz)

of the big flooded bunch of signals, and W6XW in California

was blowing the receiver away in CW - of all things.  An indoor

radio and whip antenna - he must have been 40 or 50 dB over

S9.  And this was an FM receiver - so - the Morse Code was

inverted.  The receiver was quiet when he transmitted, and

noisy in between characters.  (I think this was the fall of 1981.(?)

The only other interesting weird thing I can think of is - in the

late 1980s, in the Spring, I heard a strange signal for hours in

the afternoons.  It was some kind of sporting event in the 46 or

47 MHz range.  My mind wants to say 47 - but that doesn't fit in

with any audio- television channel 0 or channel 1 assignments that I

can think of - from anywhere in the world.(?)  Maybe it was a

feeder.  That one was really strange.

Yeah, the guys who have seen TV channel 2 or 3 F-skip - even

if it is too distorted with phase shifting and that sort of thing to ID- -

that is still a once in a lifetime thing.  And it will never happen any more,

as we know.

Oh - I did talk to Japan on 10 meter SSB with an indoor antenna

in my  Cinnecticut apartment.  But it was with 100 watts, so it really wasn't

a big deal at that time. 

We have another thing  in common.  I really like longwave, too.

When the heck are they going to open up that 472 to 479 kHz

band??.  Like - I am SO on there!  Or want to be...

Gotta love it!

Bruce