From: Garey Barrell 
Subject: Re: [drakelist] TX4C Power Output problems


Garey Barrell  made an utterence to the drakelist gang
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Larry -

First step is to bridge C107, the Twist-Lok capacitor with a good 60+ uF 
{at} 250V+ cap.

Next check R44 680 ohm 1/2W decoupling resistor for the 12BY7A driver 
stage plate supply.

Check bias supply in the AC-4, particularly the dual section Twist-Lok 
electrolytic filter cap.

73, Garey - K4OAH
Atlanta

Larry Groom wrote:

> I just aquired a TX4C that is having some quirky problems. When I put 
> the transmitter into
> the Tune mode after it's tuned, the power will jump to 100 watts and 
> then drop down to 60 watts
> after approx. 10 seconds. If I then tweak the gain control to a higher 
> postion (ie move CW) the power
> will return to 100 watts and stay there. I've taken the rig to a 
> friends house who's very sharp on these
> tube types. After poking around he discoved that the problem may be in 
> the sidetone generator circuit.
> He was able to see that the tune signal drops off as it enters the 
> tube (can't remember the tube number)
> and I was also told the my mic. audio was getting distorted as I was 
> using it. (I imagine if I had increased gain
> in may have come back) Also, when I tried to use the rig in CW mode 
> the rig would go into transmit mode and
> then drop out quick, just a beep and back to receive, irregardless of 
> VOX setting.
>  
> Has anyone had this type of problem or any ideas?
>  
> Larry W0FLY

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