Re: Mod For popping & AGC on Argosy


From: Robert J. Gobrick (
Date: Sat Jun 15 1996 - 08:02:51 EDT

Hi John,

I'll be curious what feedback you get on the Argosy AGC popping (well known
phenomena). You'll have to filter the information you get since the AGC
circuits are different in the Argosy Analouge rigs (maybe even two versions
of AGC) and the Argosy Digital (525D). From what I remember, from an old
analog I used to own, is that the AGC popping is less (although not gone) in
my Argosy digital.

I've seen some suggestions which were not documented (ie real life tested)
so I'll see if I can dig those out of my archives.

Anyone out there play with the AGC on their Ten Tec Argosy Digital rigs?

Cheers and 73/72 Bob VO1DRB/WA6ERB

At 19:07 6/15/96 +0000, you wrote:
>Don't know about the Omnis but one of the reasons why the Argosy II
>525D has "pops" during QSK operation is that the AGC voltage, that
>is built up across C25 (10uF), is effectively shorted out by Q6 as
>soon as the key is pressed, thus ensuring that the RX comes back on
>full gain - not good news on strong signals. I believe that what is
>needed is a way to keep C25 charged during key-down. Could this be
>done with a pair of CMOS switches? There's probably a better way.
>Any ideas?
>Looks to me as though increasing C40 would increase the mute time of
>the audio amp, U4, thus allowing AGC recovery before the mute ends.
>Guess the acceptability of this depends how fast you like QSK
>operation but I shall give it a try.
>Cheers and 73 de John, G3RHP
| Bob Gobrick - VO1DRB/WA6ERB/VE2DRB - Newfoundland, Canada |
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