From: "Don and Diana Cunningham" 
Subject: Re: [drakelist] TR7 mode switch thump. PROBLEM FOUND


"Don and Diana Cunningham"  made an
utterence to the drakelist gang
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Thanks for that tip, Carel!  I'll check my two and see what I find now.
Vy 73,
Don, WB5HAK
----- Original Message ----- 
From: "Carel, PA0CMU" 
To: 
Sent: Friday, November 26, 2004 5:03 PM
Subject: Re: [drakelist] TR7 mode switch thump. PROBLEM FOUND


>
> "Carel, PA0CMU"  made an utterence
to the drakelist 
> gang
> ----------------------------------------------------------------------
>
> Hi all,
>
> The problem of the mode switch thump has been found.
> On the early version of the 2nd IF/Audio Board, R1187 doesn't exist. On 
> the late version board Drake added R1187 (10K) in series with CR1119 but 
> made a mistake in the copper trace design. In some (or most ?) cases, 
> R1187 is short-circuited! Switching to CW mode still charges C1151 
> (22uF/16V) immediately through CR1119, thus giving a loud click in the 
> audio circuit.
>
> I added a 10k resistor to my early version board and Rien - PA0TRT, 
> modified the copper trace of his late version board. Both TR7's (S/N 3157 
> and 9345) are switching without any click to CW mode now.
>
> 73, Carel - PA0CMU.
>
> _________________________________________________________________
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>
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On Behalf of "Don and Diana Cunningham" 
Submissions:        drakelist{at}www.zerobeat.net
Unsubscribe:        majordomo{at}www.zerobeat.net - unsubscribe drakelist in body
Hopelessly Lost:    majordomo{at}www.zerobeat.net - help in body of message
Zerobeat Web Page:  http://www.zerobeat.net
Brought to you courtesy of TLCHost.net  http://www.tlchost.net/
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