Posted by
Mike, W8ENG on
Nov 16, 2004; 1:23am
URL: http://elecraft.85.s1.nabble.com/Low-voltage-on-AGC-threshold-tp371652p371654.html
Don, Thanks for the fast reply.
I did have the FR gain fully CW during the test. Anyway, I just checked
(for the third time) the solder joints on the control board. Pin 4 on RP6
may have had a cold joint. I touched it up, and will re-assemble and
recheck the votltage.
73
Mike, W8EMG
----- Original Message -----
From: "W3FPR - Don Wilhelm" <
[hidden email]>
To: "Mike, W8ENG" <
[hidden email]>; <
[hidden email]>
Sent: Monday, November 15, 2004 7:34 PM
Subject: Re: [Elecraft] Low voltage on AGC threshold
> 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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