Path: utzoo!utgpu!watserv1!watmath!att!tsdiag!davet
From: davet@tsdiag.ccur.com (Dave Tiller N2KAU)
Newsgroups: sci.electronics
Subject: Re: Boosting output of a little walkie-talkie
Message-ID: <1052@tsdiag.ccur.com>
Date: 31 Jul 90 15:06:14 GMT
References: <3011@media-lab.MEDIA.MIT.EDU>
Distribution: na
Organization: Concurrent Computer Corp. Oceanport NJ
Lines: 47

In article <3011@media-lab.MEDIA.MIT.EDU> 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?  

No. Unless you find a very high current op amp, you can't supply enough
current (remember it is power we're talking about here) to get 3-4 Watts.
Most op amps can only source a few mA.

-Legal?  

Probably not. You didn't mention what band the walkie talkie is in, but if 
it's anywhere but the Citizen's band, what you propose is _very illegal_.
Please don't add to the already widespread problem of illegal operators
in the non-CB bands.  I spend enough time chasing after illegal operators
brazen enough to operate _inside_ the Hams bands, I don't want to have to
chase people in the cordless phone band as well.  (flamestopper: I only
actively chase and tattle on people that infringe on my rights as either
a legal Amateur operator or cordless phone user.  This does not include
inconsiderate _legal_ operators. Case in point: the commercial fishermen
on 10m FM 28.185)

-If it isn't possible, how could I boost the signal to increase the range?
If it's in the CB band, buy a better one. They do sell 4 Watt handhelds.
If it's a 49MHz version, either use better receivers or by a 4W CB one.

-Also, can the crystals just be desoldered and replaced with different
-frequencies as long as you get crystals of the same type?  Or are
-other things in the circuit tuned to the crystal's frequency?

Sort of.  If the crystals are reasonably close to the design frequency,
you shouldn't have too much trouble by just replacing them. (Just how far
you can go depends on the design of the radio and the frequency you're
dealing with.)  If you want to go relatively far, you'll have to re-tune
the front end of the receiver and parts of the transmitter.
-
-Adam


-- 
David E. Tiller         davet@tsdiag.ccur.com  | Concurrent Computer Corp.
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