Re: #bitx40 #ubitx #ubitx #bitx40

Tim Gorman
 

On Mon, 26 Mar 2018 22:10:07 -0700
"Jerry Gaffke via Groups.Io" <jgaffke=yahoo.com@groups.io> wrote:


If the audio is not loud enough then increase the control voltage, up
to a max of 10 or 12v. Should be easy enough with an op-amp.
Though I have not done this, or ever designed an AGC system.
So take this advice with a large grain of salt. 
How do you decide if the audio is not loud enough? Especially in a
simple receiver like this? AGC usually works just opposite of this. It
is based on audio being too loud.



If for some reason you can't use the 10v swing, then could add a 5dB
amp prior to the attenuator. Or maybe goose up the bidi amps for a
little bit more gain.
This would seem to be eminently doable.


I'm thinking the attenuator should be in series with R37, 
the BAP64Q is designed for use in a 50 ohm environment.
R17 might be better. The 45Mhz filter is pretty broad. A mismatch here
might affect the receiver operation less.

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