Posted by
Don Wilhelm-3 on
Nov 16, 2004; 12:34am
URL: http://elecraft.85.s1.nabble.com/Low-voltage-on-AGC-threshold-tp371652p371653.html
Mike,
Since your adjustment range is on the 'edge of the cliff', it would be a
good idea to identify what is causing it before it bites you later on.
Check all the components for proper values and check solder connections very
carefully to determine why you are running out of adjustment range. Look at
the schematic to determine which components are connected to the AGC
threshold pot circuits and check them all with a careful eye, then check
again and when you have finished, check it once more - these things are
difficult to spot even with careful inspection (I know, I've been there,
done that many many times).
3.78 volts may be fine for the AGC Threshold adjustment - I often (usually)
find that the proper AGC threshold is between 3.6 and 3.8 volts.
Just as an afterthought - you do have the RF gain control full clockwise do
you not? It will alter the reading on the AGC threshold measurement point.
73,
Don W3FPR
----- Original Message -----
When setting the AGC threshold I was not able to get 3.8 volts on pin 5 of
U2 as described in the manual. The voltage varied from 2.60 to 3.78 when
adjusting R1 to the extreme settings. Is this close enough or should I have
more room for adjustment?
I have a faily good DMM, and it compares very closely to the K2 internal
meter, and when checking values on 1% tolerance resisters. All other checks
to date have been fine.
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