Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!unmvax!bbx!yenta!dt
From: dt@yenta.alb.nm.us (David B. Thomas)
Newsgroups: sci.electronics
Subject: Re: Boosting output of a little walkie-talkie
Message-ID: <1694@yenta.alb.nm.us>
Date: 1 Aug 90 07:56:30 GMT
References: <3011@media-lab.MEDIA.MIT.EDU>
Distribution: na
Organization: yenta unix pc, Rio Rancho, NM
Lines: 34

adam@media-lab.MEDIA.MIT.EDU (Adam Glass) writes:

>Could I use a high-frequency op-amp as a voltage follower to amplify
>the output of a little walkie talkie?  I'd like to increase the thing
>to more than 100mW and get enough output out of it to boost the
>effective range up to a mile or two.  Maybe up to 3 or 4 watts.

>Is this possible?  Legal?

Yes, no.  Fun and useful?  Yes.

The circuit you are looking for is available from a hobby mail order outfit:

	Panaxis Productions
	P.O. Box 130
	Paradise, CA 95967-0130
	(916) 534-0417 M-F 9am-6pm CA time

They sell plans and kits for all sorts of things, including bugging and anti-
bugging devices, pirate radio gear, radio transmitters and amplifiers of
all sorts, etc.

I have bought (but of course never used :-) several of their products.  The
plans are often sketchy, but the circuits always work as advertised, so far.

The specific product you want is the "peak power booster".  It's an
ingenious walkie-talkie power amplifier.  It switches your carrier on and
off 8,000 times a second, providing 5 watt peaks, but averaging very low
current (long battery life).  The receiver is very unlikely to be able to
reproduce the 8,000 Hz whine and will get only your voice, just as strong
as if it were transmitted 5W continuous.  I haven't built this one yet,
but the plans look easy enough for a hardware hacker type.

						David