Gerhard, That small negative voltage may be coming from the AC ripple on the '90-150 V' supply to the TR switch that is being coupled through the RF chokes and capacitors into the Q1 and Q2 collector circuit and then being rectified by the transistors themselves. If that is the case, it may not be a problem at all once you connect a +12 volt supply.
Put an RF probe on the cathode of D13 and see how much RF voltage is present there (it would be at the approximate frequency of X1). 73, Don W3FPR > -----Original Message----- > > > 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! > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
