[SignalOne] CX7A arcing follow-up

Fri, 1 Nov 2002 14:38:54 -0500

Hi.  I've been reading your mail about your arcing problem.
While a defective tube will cause the problem you describe I
have experienced the same thing in repairing such sets that
you might want to check:
    . Parasitics---check the parasitic suppressor resistors.
Sometimes the tube is good and is driven into saturation
when this happens.
    Bias components---I have seen CR-1 become erratic and
momentarily pull down the bias; a failure of C30 on the
driver board can cause the same problem.  Also, changing the
1.0 ohm/ 1.0 watt resistor to a 1.0 ohm/ 2.0 watt resistor
sometimes corrects the problem---worth a try if all else
fails.
Good luck, Jim, KI4EN.
----- Original Message -----
From: "W2AGN" <[email protected]>
To: <[email protected]>
Sent: Friday, November 01, 2002 11:44 AM
Subject: [SignalOne] CX7A arcing follow-up


> Thanks to all who responded. S/1 owners are a great bunch.
>
> It appears it is the tube. If I disconnect the socket, and
apply B+, no
> arcing, but with socket connected, it blows the 1 ohm
resistor. Hopefully
> have replacement on the way.
>
> Oh, yes, one other think I learned. The CX7A power supply
doesn't have
> much of a bleeder. It's OK, I'll be able to use that hand
again in a day
> or two  ;-)
>
>
> ---
> +-++-++-++-++-+   John L. Sielke
> |W||2||A||G||N|        http://www.w2agn.net
> +-++-++-++-++-+    Ex-K3HLU,TF2WKT,W7JEF,W4MPC,N4JS
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