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

[Gerhard Schwanz]

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