Paul,
You may find some information in the archives that could possibly help
your situation. Jack Smith K8ZOA has documented a good amount of info
on the AGC operation on his website and Dave White VE6DRW has created a
mod to give more control over the various AGC characteristics.
Look for their posts to the reflector in the February and March 2007
timeframe.
It is quite likely that neither of those sources will produce the
'strong AGC' that you seem to desire (most of us like the softer K2
AGC), but may be worthwhile for study as a prelude to your re-design of
the K2 AGC.
On the lack of ability to get the AGC Threshold up to 3.8 volts - do not
be overly concerned about that - the maximum voltage is related to the 8
volt regulator actual voltage. Furthermore, if your AGC is active even
with no signal, you should *lower* the AGC Threshold voltage. I know it
sounds counter-intuitive, but results from the point where the voltage
is measured. Warning, if your AGC Threshold voltage is too low, your
S-meter settings will become a bit 'squirrelly', and for that reason I
recommend that you do not reduce the AGC Threshold below 3.65 volts in
any case.
Changes from the 'standard' designs and settings may be made, that is
part of the K2 'fun' - try it and see what happens, you can always set
it back to the 'standard'.
73,
Don W3FPR
Paul Pollock wrote:
I am enjoying my recently completed K2-6148 very much, but I had a
couple of questions and thought others might have some constructive
thoughts.
While some folks like a slightly soft AGC in the receiver, I'm one of
those folks that finds that soft signals received softer than loud
signals (especially SSB) is tiring. I prefer a very stiff and level
AGC. Mind you, this has nothing to do with the fast/slow delay rates
or anything along those lines.
1). My K2 exhibits good AGC performance and I believe it works as
designed, but it is a soft AGC. Are there any ideas on modifications
to the AGC IC (LM833) that might stiffen the AGC performance?
2). I'm another of those folks where my AGC threshold voltage will not
go above 3.7x volts. It is my feeling that a threshold set so that the
AGC actually releases at the noise level is better than a setting
where the AGC is ON at all levels. On my K2 the AGC never releases at
any level. Any thoughts on getting the AGC to release correctly?
_______________________________________________
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
