Ed,
Thanks for your help with the sidetone on Century 21. I put a small, 100K
trimpot across R1
and now I can adjust the sidetone. Also pulled the speaker audio out
through a closed-circuit
quarter inch phone jack so I can feed the C-21 through QF1-A audio filter
and outboard
audio amplifier.
73
George, W4GFA
----- Original Message -----
From: "Ed" <w3nr@comcast.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Friday, August 21, 2009 4:29 PM
Subject: Re: [TenTec] C-21
> George Allgood wrote:
>> Recently, I found a Century 21 and let it "follow me home".
>> Rebuilt the PTO and cleaned her up a bit and now, she's working like a
>> charm.
>> I'd like to change the frequency of the sidetone. The sidetone is plenty
>> loud enough,
>> but the pitch is a bit low. The tone is generated from an IC on the
>> pre-amp board.
>> Has anyone done this?
>>
>> Thanks
>>
>> George, W4GFA
>
> R1 controls the sidetone frequency. It will be either a 68k or a 47k. I
> put a variable pot in temporarily to determine what I wanted. Measured
> the pot and used a fixed value.
>
>
> Ed W3NR
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