Using a Signal Generator for an "In Home" radio transmitter

Yeah, but it'll sound like crap. Because most of those old generators will only do about

30% modulation. And they're not exactly set up for any kind of modulation bandwidth.

There's the SSTRAN 3000 which I use. Another option is the Talking House transmitter.

Or, you can roll your own.

--
"I am a river to my people." 
Jeff-1.0 
WA6FWi 
http:foxsmercantile.com

It is absolutely possible. And, the quality of the signal transmitted will be based on the quality of the generator. BUT:

Make sure your radiated power does not exceed FCC part 15 limits. Which, as I remember, is about 100 mw on the commercial AM band. Also, make sure you do not exceed antenna 'developed length' - which is very roughly ten (10) feet. You will get better results if you trim your antenna to the target fr equency. When I lived and worked in Saudi, I covered 80 acres with an SSTRA N transmitter, using a based-loaded coil mounted about 10 meters above grad e, and transmitting on 1380 AM. Not so good on the stucco-on-mesh villas, s o I converted to FM in short order, using a Ramsey FM100B (1-watt). That co vered a radius of about 5 km in good stereo.

Look up the FCC Part 15 rules for Medium Band AM.

Peter Wieck Melrose Park, PA

You're off by a factor of ten. You want up to 1,650 KHz. Actually it is so easy to build an oscillator like that and easy to amplitude modulate that m ight be a better option. Well unless you have nothing better to do with the generator.

Crystal controlled would be better because drift is not good. But then if y ou just leave it on all the time it will settle in and be stable enough.

Another thing is to keep the power down, you don't need problems with the F CC. They got a SWAT team, I shit you not. I am not sure what you can get aw ay with, maybe 100mW or 500, something like that. A quick Google didn't yie ld a straight answer but I would say just make sure the signal doesn't leav e the house.

I know it is absolutely illegal to use any of the FM band, that this when t hey come and treat you like you're running a meth lab. However there is so much noise on AM that they might never even suspect. You might be better ru nning the "transmitting antenna" through wires to the desired locations. I fit leaves the house, even on your own property that might mean trouble. An d we are talking feds here, that means your miracle worker lawyer is no goo d.

Yes. Your signal generator can be used for that. I doubt you need more than a foot or two of wire for the antenna. The frequency you mentioned, however, isn't MW. It's short wave (which may possibly be received on your antique radios in addition to MW). Perhaps it was just a typo on your part, but the AM broadcast band is from 540 to

1700 kHz (formerly referred to as kc). 1600 to 1700 wasn't part of the band until after any radio called antique was sold, so 540 to 1600 is what you want to use.

Have Fun, Pat

Which is all well and good, but old table AM radios don't do FM.

--
"I am a river to my people." 
Jeff-1.0 
WA6FWi 
http:foxsmercantile.com

I'm not sure what you meant by "trim your antanna to the target frequency". If you are talking about an antenna that is resonant at AM broadcast band frequencies, that is not practical (or legal as you correctly pointed out) for a home transmitter. One wavelength at 1600 kHz is 187 meters (over 600 feet).

Think of PowerLine.

No problem:

"Cuthbert FM to AM Converter MKII"

This solves the problem for those who can't find anything worth listening to on AM, but want to listen on an antique radio. So, they listen to FM broadcast on the AM radio.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Short answer: NO. Longer answer: Check the FCC regulations for what you're allowed to do on what frequencies. Depending on where you live, you might get in trouble if some harmonic landed on some emergency frequency.

Turn on the generator; tune the radio to that frequency;Is the unmodulated signal absolutely quiet on your radio? Let it sit for an hour; is the generator still on the same frequency as the radio? If you got this far, you might have a chance.

Well, yes, it's possible. But, it isn't necessary. There are Bluetooth options if your 'antique' radios can accept a bit of straightforward audio input. A variety of MP3-compatible Bluetooth players (like, maybe in your cellphone?) can be found, with Bluetooth output, and receivers are a common item: some inductive coupling to the audio signal channel could be easy to arrange.

If you can put an induction coil in the vicinity of the radios, it doesn't take much power to tickle an AM radio, with minimal AM interference at longer distances.

This app note comes to mind:

note especially figure 116

Very cool! I actually have a tube AM transmitter that I built from a Lafayette kit in 1970. Found a photo and description online:

The design seems typically dangerous for the time, it's a wonder I managed not to electrocute myself or blow up other equipment with this thing! It would be interesting to try resurrecting it with some appropriate safety modifications.

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All things are possible if you have enough time and money to throw at the problem.

In college, we threw together a radio station based on an AM carrier current broadcast system. The key to the system was the isolation transformer between the transmitter output and the AC power line. You don't want 60 Hz going backwards into the transmitter causing hummmm and you do want the frequency response of the transformer to include the AM broadcast band. That's not easy as there are a bunch of compromises that need to be made. Our first transformer literally exploded when plugged in. Our 2nd version did a little better by only catching fire. When we tried to measure the RF impedance of the power line at 900KHz, we blew up the signal bridge.

We eventually bought a commercial system after the fire marshal decided that he would not tolerate an untested system. I got lucky and found an original data sheet: Note the T-8 power line interface. On Page 6 it lists "Univ. State Poly, College" (Cal Poly Pomona) which is where we built the system.

A tube type LPB carrier current transmitter:

Doesn't have enough RF power for carrier current. It can probably be heard somewhat all over the house, but will probably be noisy.

Try 1650 KHz instead. Kilocycles died 50 years ago.

I wrongly assumed that you wanted to do it down the power lines using a carrier current system. Yes, an inside antenna MIGHT work. I'm fairly sure that your signal generator doesn't belch enough RF power to be heard around the house without background noise. I suppose it would easy enough for you to try with your existing generator.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Go to the section on "tuning".

Peter Wieck Melrose Park, PA

they come and treat you like you're running a meth lab. However there is s o much noise on AM that they might never even suspect. You might be better running the "transmitting antenna" through wires to the desired locations. I fit leaves the house, even on your own property that might mean trouble. And we are talking feds here, that means your miracle worker lawyer is no g ood.

No. There are multiple FM & FM stereo Part-15 compliant transmitters. Typic ally, they are around 25 MW or so, and with a good antenna mounted high eno ugh will easily cover a few acres.

rge.jpg

I keep this one, and it gets its heaviest use at Kutztown twice per year, c overing both pavilions, and then some. Matched to this antenna:

nna-kit---25-watts-.jpg

There are (at least) half-a-dozen more options.

Eventually, I am would like to set up a small NTSC TV transmitter, as TVs a re becoming a greater and greater presence at Kutztown. But, it is somethin g I would never use at home.

Peter Wieck Melrose Park, PA

are becoming a greater and greater presence at Kutztown. But, it is someth ing I would never use at home.

Years ago, I used to feed my shop's cable box into a distribution amp to co ver the several drops I had around my store, one of which I fed into an ant enna. This would allow quick verification of TVs with just putting my fing er on the antenna terminal of any TV. One day the cable co. shows up and s aid we had a huge leak and wanted to check for an open ground. I switched off the AB switch feeding the antenna and the problem was gone.

In any case, you can try feeding the RF output of any VCR or any RF modulat or into a decent VHF amp and feed an antenna. Probably cover the area you need without spending any money.

I do it the other way, I feed antique radio programs from my internet radio into my FM transmitter, so I can listen on my portable radio.

Two of my favorite Old Time Radio Stations,

Stoke up the fire and listen to,

Sherlock Holmes Johnny Dollar Philip Marlowe Dragnet- Features Jack Webb and advertises Fatima cigarettes >

of Fantasy The Bob Hope Show Have Gun Will Travel Escape Bold Venture with Humprey Bogart and Lauren Bacall Tarzan The Whistler Richard Diamond The Lives of Harry Lime Orson Welles does the lead role Broadway Is My Beat Bob & Ray Suspense Box 13 Philo Vance The Lone Ranger Screen Director's Playhouse The Six Shooter Gunsmoke ?William Conrad did the voice for Matt Dillion Fort Laramie Raymond Burr does the lead role. X Minus One

Mikek

And how is that supposed to work with a bunch of AM radios?

--
"I am a river to my people." 
Jeff-1.0 
WA6FWi 
http:foxsmercantile.com

You feed the headphone jack of the FM radio into an AM XMTR...

Sheesh Jeff!!