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From: dana@lando.la.locus.com (Dana H. Myers)
Newsgroups: sci.electronics
Subject: Re: Boosting output of a little walkie-talkie
Message-ID: <15102@.la.locus.com>
Date: 10 Aug 90 21:44:01 GMT
References: <90080614412836@masnet.uucp> <38070@ucbvax.BERKELEY.EDU>
Sender: news@locus.com
Organization: Locus Computing Corporation, Inglewood, CA
Lines: 26

In article <38070@ucbvax.BERKELEY.EDU> hull@janus.Berkeley.EDU) writes:
>
>An antenna is hooked up so that it looks like a short circuit at D.C. and
>is usually 75-300 ohms at the RF frequency.

    Not necessarily, it depends on the matching networks in use.  Some
antennas have 'baluns' or some form of shunt matching network installed. For
instance, a quarter-wave ground plane which has the radiating element
perpendicular to the ground plane will not directly match a 50 ohm line. A
match may be achieved by placing some 'shunt reactance' from the radiating
element to ground, this could be an inductor or capacitor. An inductor would
appear as a DC short to ground. (IMHO, the best way to match a quarter-wave
is to droop the radials)

>Design of a power amp also requires transistors with enough power handling
>capability.  The design requieres some knowlidge of electronics beyond 
>Ohm's law.

    I'll second this motion. An improperly built RF power amp can be a
real nuisance. I've seen some real hacks out there. For the record, I've
built several amps from scratch, sometimes just to experiment.
*****************************************************************
* Dana H. Myers KK6JQ 		| Views expressed here are	*
* (213) 337-5136 (ex WA6ZGB)	| mine and do not necessarily	*
* dana@locus.com		| reflect those of my employer	*
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