Thread: Pre amps
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Old September 20th 04, 08:39 PM
Allodoxaphobia
 
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On 20 Sep 2004 11:00:44 -0700, David Harper hath writ:
I'm still new in regards to radio, but had a couple questions
regarding equipment. I've seen some info about pre-amps, and was
wondering if this is just a low-power transmitter that "should" have
an amp between it and the antenna. Is the preamp basically everything
before the power amplifier? If not, where am I mistaken?

Thanks in advance!
Dave


There are preamps, and there are preamps.
In general, a preamp is used to amplify a Very Low Level signal
up to "general, utility" levels.

E.g.: A mic preamp is used to amplify the Very Low Level signal
of a microphone up to a level where the audio circuits can
better modify and/or filter it. Or, a rcvr preamp is used at the
front of a receiver's antenna input to get the rf input up to a level
where the signal(s) can better be mixed, filtered, or modified.
There are many considerations in the design of a preamp -- but
foremost, maybe, is the design for low noise due to the fact
that these signals do not stand very tall over whatever noise
exist in the system.

Preamps may be external or internal. I.e., a mic preamp could
be found in the base of the microphone, on the cable, or in the
device (transmitter, P.A., etc.) to which the mic is connected.
Same-o for a rcvr preamp: It could be mounted up at the antenna,
somewhere in-line in the transmission line, or inside the receiver.

HTH es 73
Jonesy
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