HFU HF Underground
Technical Topics => Part 15 AM and FM Station Operation => Topic started by: Tim Bucknall on August 25, 2018, 1250 UTC
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is anyone keeping score?
AM & FM would both be interesting
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I had an ersatz Part 15 in the 80s (an AM broadcast RAdio Shack P-box), and I ran higher power than the transistor was designed for (18V instead of 9V), and it was clearly audible on my portable radio over two blocks away. I had it tuned to an empty spot in the 1400's.
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There was a local guy that had a range of about 2-4 miles on AM in the daytime depending on the time of year. I heard the carrier 6 miles away, but w/ no audio.
It was straight up legal, but he'd been at this stuff for years, he knows how to tweak it. I couldn't believe it.
I fooled w/ 10 mW's of FM and a wire dipole on and off for a few years. I live on the end of a ridge and have some height. I could get a half mile, give or take, depending on whether the leaves were out. That one was strictly by the book and surprised me. I was thinking a couple of hundred yards, tops. I just wanted to hit the bars at the bottom of the hill at closing time.
The tx was one of the infamous Ramsey 10 series, a noted spur generator. I live on the flight path to two airports. I wasn't about to amplify that noisemaker. No point in pissing off two Gov. agencies.
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Cool stories guys, thanks
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I've imported a talking house tx to England, as a tech novice the auto ATU is a godsend.
The Stepdown transformer doesn't seem to have compromised the txs inbuilt earth system
I initially tried the top of the expanded band as recommended by the instructions but it's much happier lower down.
Yesterday I got 4 miles on car radio on 1440 which is currently empty in Europe but not for long
My goal is to have the carrier spotted as a trace by the carrier monitoring guys at DX distance with their ultra sensitive set ups
I guess you could call it a medfer with voice loop basically.
I'm a frustrated AM dxer, the band is lost to noise here but I still want to do something with this fascinating band before noise kills the hobby everywhere.
We're having somewhat of a LPFM boom in England right now, with most operating in the hazy area between I-TRIP and 0.5 watt pirate with an eBay tx
A few Sundays back I think we must have hit peak LPFM.
At a local hilltop the band was full of stereo blank carriers as well as the music pirates
From home the same day using an FFT display, I counted at least 5 permanently on stereo carriers on 108 with associated stereo sidebands.
That seems to have been an exceptional day.
It's nice to see, none are strong enough to interfere with dxing
It would be nice to get your part 15 regs pasted into UK law after Brexit, it encourages science and engineering skills and would provide relief from the hideously dull state of commercial radio in the UK.
Our community radio stations were supposed to do this but outside the big cities CR just copies commercial radio formats
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For am daytime use you might want to go vertical due the d layer absorption, d layer devours vertical polarity least. After sundown it doesn't make much diff save for in the near field when you want the rx and tx polarity to be the same as the losses from polarity mismatch can be high, d layer goes away with sunset.
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It would be nice to get your part 15 regs pasted into UK law after Brexit, it encourages science and engineering skills and would provide relief from the hideously dull state of commercial radio in the UK.
I'm in the US, and really appreciate the relatively generous allowances provided for by our Part 15 regulations for the AM band, contained in 15.219. However, New Zealand have us all beat. I would love to have the ability to run 1 watt license-free on the FM band, as described in this article from Radio Survivor. Just imagine how cool that would be!
http://www.radiosurvivor.com/2017/01/03/new-zealand-legal-unlicensed-low-power-fm/ (http://www.radiosurvivor.com/2017/01/03/new-zealand-legal-unlicensed-low-power-fm/)
Our community radio stations were supposed to do this but outside the big cities CR just copies commercial radio formats
I think some radio enthusiasts just want to "sound like the big guys", seemingly unaware that what the big guys are doing is largely devoid of creativity, individuality, and personality.
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I had an ersatz Part 15 in the 80s (an AM broadcast RAdio Shack P-box), and I ran higher power than the transistor was designed for (18V instead of 9V), and it was clearly audible on my portable radio over two blocks away. I had it tuned to an empty spot in the 1400's.
How'd you not fry the thing? LOL.
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For am daytime use you might want to go vertical due the d layer absorption, d layer devours vertical polarity least. After sundown it doesn't make much diff save for in the near field when you want the rx and tx polarity to be the same as the losses from polarity mismatch can be high, d layer goes away with sunset.
Speaking of technical stuff.....my station can get out about 1400 feet, which covers a lot of potential listeners in my neighborhood (I live on what is basically my town's main street/commercial area). I would love to get a bit more range, though....nothing like three miles, but maybe a mile to a mile and a half would work.
Scratching my head as to how to do this.....my situation is such that I cannot put an antenna outdoors (I rent an apartment on the ground floor of my building). Any thoughts?
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Speaking of technical stuff.....my station can get out about 1400 feet, which covers a lot of potential listeners in my neighborhood (I live on what is basically my town's main street/commercial area). I would love to get a bit more range, though....nothing like three miles, but maybe a mile to a mile and a half would work.
I can just barely reach the end of my driveway :)
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Hey Matt_B!!!! Try going Carrier-Current if you are APT bound. That's how I started out, with a Panaxis AM-100 TX, (100mW TX.), to a 100uH coil and Neutral Injected that. How did it work? I was GND Floor of an APT complex and it covered into several buildings. So, not bad. Today, I have some better gear and use either the LPB T-8, or the Radio Systems CP-15, AM C-C Couplers. BTW, if you can, best to use an Independent GND rod to the Coupler. Also, look for any books about the subject from Ernest Wilson and James R.Cunningham to download and apply. A lot of stuff you can build yourself, and you might have to, since anytime LPB and RS stuff come up on ebay, they get bought out almost immediately. So, someone wants that stuff, badly.