I built the TenTEc 1340 40 meter QRP rig and wanted some extra power so
I bought one of those CB amplifiers that are so popular. Yes, these
things are everywhere! All you gotta do is put a wtb: on rec.radio.cb
and you'll get plenty of offers. Expect to pay about $125 for a 150w
model.
Mine is made by Palomar and is called the tx-150. It has an rf sensitive
changeover relay so all you need to do is simply connect your qrp's
antenna output to the amp then the amps output to your antenna. When you
tap the key, you are instantly in transmit mode. There is an adjustable
delay. Of course, you loose your qsk this way but it's sure quick and
easy.
These amps are usually advertised as covering all bands 80 through 10
meters and in fact they do. There are no tuned circuits to worry with.
Whatever harmonics you generate will be sent to the antenna. In a mobile
installation, usually your antenna has such a high Q that little
harmonics could be generated. An antenna tuner would help attenuate them
even more. In the case of 40 meters, If you stay below 7050, no one
would notice you on 20 meters anyway.
Another feature of these amps is the receive preamplifier which can be
activated by a switch to boost the rx signal another 10 or 20db. Most of
them are of the "brick" construction and resemble vhf amplifiers. They
usually require 12 volts dc.
I don't know if these things are still being manufactured but I've seen
tons of them at hamfest. Just look around for the guy with all the CB
junk! My 1340 with it's 4 watts output can drive this amplifier to 75
watts which is plenty of power.
There is absolutely nothing illegal about buying these and using them on
the ham bands.
They do defeat the whole purpose of QRP though and that is: To prove
that it doesn't take much power to establish a qso but it does take some
power to keep one.
Steve N4LQ
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