[TenTec] Argonaut 509 Bias Mod

[waltk8cv4612amos at att.net]

Well, yes and no, you can find an old AT&T telephone handset and unscrew the 
receiver and in there you will find a round thing that is the receiver and 
it drops into your hand. Look at the back of it and you will see a black 
thing soldered across the lugs. It is a 100A diode! It was to protect the 
ears of users from popping noises on the telephone line. Cut it out / off 
carefully and solder it across the headphone jack of the 509  and it will 
suppress the loud pops of audio AGC ! There are many circuits in old 
handbooks about back to back diodes to ground or across the audio lines and 
that is about the best you can do with audio AGC !

Walt K8CV Royal Oak, MI.

----- Original Message ----- 
From: "Byron Tatum" <bjtatum1 at att.net>
To: <TenTec at contesting.com>
Sent: Monday, August 03, 2009 11:41 PM
Subject: [TenTec] Argonaut 509 Bias Mod


> Hello-
>    I installed the bias modification under "Improving SSB Performance of 
> Argonaut 509". I had problems - the PA current was way too high and could 
> not be adjusted down.
>    Did a lot of checking and found nothing wrong on PA board. The problem 
> was due to the ground wire that goes from PA board socket to adjacent 
> ground lug. There is one on each end of socket. The one (at end of board 
> where bias circuit was at)  had come loose from the chassis solder lug, it 
> was not readily seen due to wire covering up solder lug. It appeared it 
> was not securely soldered to begin with. The wire had a hook shape to it, 
> and was centered around lug and not touching it (??).
>    All is well now and the PA bias did adjust correctly after correcting 
> problem.
>    Anyway, just a tidbit of info that may help someone else.
>    Speaking of Argo 509 - Does anyone have an AGC revision or update that 
> may help the "pop" on strong stations?
> 
> Thanks, Byron WA5THJ
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