Posted by
Mike Harris-9 on
Feb 04, 2005; 4:14pm
URL: http://elecraft.85.s1.nabble.com/KPA100-Problem-still-exists-but-some-new-measurements-tp374307p374308.html
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" <
[hidden email]>
To: <
[hidden email]>
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
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