Re: AGC circuit to try?

Tim Gorman
 

Jerry,

I've ordered four BAP64Q units for when my second ubitx gets here. I'm
going to stick it in the rf path somewhere as we discussed earlier.
Maybe between R17 and C12?

tim ab0wr

On Tue, 10 Apr 2018 08:05:57 -0700
"Jerry Gaffke via Groups.Io" <jgaffke=yahoo.com@groups.io> wrote:

It was just a thought, getting an AGC scheme to work well is not
trivial. I'm still thinking a BAP64Q at R17 might be best.

Base of Q70 could work.  It might do better on the other side of C50,
where that weak incoming audio is centered on ground. 
Though as we have seen here, have to think about what happens when
you have strong audio from the mike amp during transmit, potentially
going through the intrinsic diode in that FET. 

You're on your own!

Jerry

On Tue, Apr 10, 2018 at 07:32 am, Tim Gorman wrote:


I have mine connected in the receive line before the first mixer.
Your idea might work better. I assume you would put it at the base
of Q70 in the ubitx?

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