[Elecraft] KPA100 Problem still exists, but some new measurements

[Mike Harris]

G'day,

Did you have a light shining on the PA transistors?  J3+ on my KPA100 
had -0.18V.  Apparently something to do with illumination of the PA's. 
Well noted by others.

Regards,

Mike VP8NO

----- Original Message ----- 
From: "Gerhard Schwanz" <gerhardschwanz at yahoo.de>
To: <elecraft at mailman.qth.net>
Sent: Friday, February 04, 2005 10:42 AM
Subject: [Elecraft] KPA100 Problem still exists, but some new measurements


Hi there,

I'm still on page 43 in the process and I have now narrowed the problem 
area. You remember, I measured a negative voltage of 0.15V on J3+.

Now: I removed Z1 and found the voltage measured at the collectors of Qs 1 
and 2 to be -0.4V (J3+ is ok now). I don't know where it could come from. 
Shorting the collectors to ground via 1k resistor it takes 3 seconds to 
eliminate the voltage. I measure 0V. Removing the resistor it takes abt. 
20 seconds for the voltage to go to -0.4V again.

T2-4,5 are ok. The base of the transistors are ok, 0V. The emitters also, 
0V. The body of T2 also has -0.4V.

Any idea and testing procedures appreciated!

Kind regards


Gerhard Schwanz
DH3FAW
mailto:gerhardschwanz at yahoo.de
http://www.gs-personal.de


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