Hi, Barry,
It's not the signals that determine whether you need a preamp, it's the noise
level. A receiver should have enough gain to put its internal noise floor below
the external, atmospheric noise floor, so that it doesn't become the limiting
factor in hearing weak signals close to the noise. That's what makes a preamp
necessary.
Certainly, if your noise floor is lower than here in urban North America, there
may be cases where a preamp does us no good, but is necessary for you.
I think I once posted a case study here a while ago... but I would have to go
searching for it. The numbers I used were definitely US-biased. Life for a ham
here has become a really discouraging exercise in trying to copy signals below
your neighbors' app-enabled pet massagers and internet-controlled wine coolers,
all fed by those infernal switch-mode power supplies. My two neighbors' homes
are really just enormous square wave-producing things. This is also why
everybody you hear is running 1,000 watts or more. It's power inflation. The
military spends millions on radar jamming equipment... when all they'd have to
do is do whatever my neighbor Johnny is doing. He must have a phased array
radar, arc-welding, barrage jamming plant next door. If you ever bring your rig
over here on vacation, be sure to pack a 60 dB attenuator with it.
R,
Al W6LX
From: Barry Simpson <vk2bj...@gmail.com>
To: elecraft@mailman.qth.net
Sent: Saturday, April 7, 2018 2:25 PM
Subject: [Elecraft] K3 Preamp 2
I often see posts from US stations questioning the need for any preamp below
20m and just now challenging the need for preamp 2 on 10m.
That may be all well and good in the land of the huge antennas and the
thousands of big signals from the US and Europe but let me tell you that down
here, when you are scratching around for weak signals on 10m and 12m, preamp 2
makes a world of difference.
Barry Simpson VK2BJ.
Sent from my iPad
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