Article View: sci.electronics
Article #5555Re: Boosting output of a little walkie-talkie
From: USENET News Administration
Date: Thu, 09 Aug 1990 23:04
Date: Thu, 09 Aug 1990 23:04
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> > 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.
>
>Why high current? There is very little current travelling through
>the antenna, so you'd require a higher voltage, wouldnt you? After
>all, P=VI... And air is a very good insulator. A high current would
>be impossible, at reasonable (below 1,000,000 Volts) voltages.
>
>
> -=Peter Saulesleja=-
>
>
>--- Opus-CBCS 1.13
> * Origin: Nowhere(833-2814) "I hate origin lines!" (1:250/630.0)
From: hull@janus.Berkeley.EDU (Christopher Hull)
Path: janus.Berkeley.EDU!hull
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. You need both higher voltage
and higher current to put out large amounts of power. Tranformers can be
used to convert a high voltage and low current to a high current and low
voltage or vice-versa. A standard 9v Cell will not delver enough power
to drive more the 100mw for a reasonable amount of time. Hence, most
powerfull C.B.'s use banks of 8-12 AA cells to derive the necessary
power output over a sustained time.
Design of a power amp also requires transistors with enough power handling
capability. The design requieres some knowlidge of electronics beyond
Ohm's law.
Chris Hull
hull@Janus.berkeley.edu
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!ucsd!ucbvax!usenet From: usenet@ucbvax.BERKELEY.EDU (USENET News Administration) Newsgroups: sci.electronics Subject: Re: Boosting output of a little walkie-talkie Message-ID: <38070@ucbvax.BERKELEY.EDU> Date: 9 Aug 90 23:04:31 GMT References: <90080614412836@masnet.uucp> Reply-To: hull@janus.Berkeley.EDUIn article <90080614412836@masnet.uucp> peter.saulesleja@f630.n250.z1.fidonet.org (peter saulesleja) writes: Organization: University of California at Berkeley Lines: 37