There are two major problems with turning off the K3's AGC:
1. There is very little dynamic headroom until the AF Limiter
causes severe distortion on even a moderately loud signal, even
if the AF Limiter setting is max.
2. Never use the speaker amp with AGC turned off. It takes just
one dit from a loud signal to destroy the delicate speaker
amplifier IC. That will require a $110 factory repair, plus
postage.
Dave Hachadorian, K6LL
Big Bear Lake, CA
-----Original Message-----
From: Kevin Rock
Sent: Tuesday, June 21, 2011 10:12 AM
To: Elecraft
Subject: [Elecraft] [K3] AGC-OFF
I was having a hard time making out characters today during my
daily sked
into the Southeast. The QSB was a fast flutter and was chopping
up the
letters badly. I was running fast AGC and thought maybe slowing
it down
may help. It did - a little. So I took the next logical step
and turn
AGC off entirely. The characters popped right out at me. I just
rode the
RF gain as the signal went through its slower QSB while the fast
flutter
QSB did little to bother me. AF gain was cranked to high as I
normally
run it while RF gain was set to where the background QRN was
minimized.
Turning off the AGC helped eliminate the fast flutter problems
which were
causing me difficulties copying.
This is most likely old news to many of you but I have been
running AF
gain at max and controlling volume with the RF (or IF) gain since
1960
when I first started SWLing on my brother's Lafayette receiver.
I hope this helps at least one of you drag out a new one.
73,
Kevin. KD5ONS
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