[SignalOne] CX-7A saga

[JLittlejohn W9NET]

Hi, gents.  My CX-7A repair has been a fascinating winter project, occupying
a tremendous amount of time during which I have learned an awful lot.  I've
received a number of suggestions from you all and it has been most
appreciated.  It all started when it worked for a little while and then blew
the fuse.  It then started to blow fuses on initial turn-on.  I replaced the
HV and 15V rectifiers and some associated transistors on the power supply
board, and also all the filter condensers just for fun, and now the supply
works great.   The radio still blows fuses, but only after the Amperex delay
relay kicks-in at 60 sec. to turn-on the bias to the 8072 (which is brand
new-NOS).  I get appropriate voltages to the 8072 socket, with the tube
removed, and the receiver side works fine.  With the tube replaced in the
socket, if I disconnect the HV transformer leads, the receiver works fine.
I've checked all the NPN and PNP transistors on the RF Driver board, and
they are OK.

Does this sound like I have a problem with the FET's on the driver board?  I
guess I'd have to install new ones to see, unless someone could come up with
a way to take a different approach.  The one thing I haven't done is
disconnect the driver connection to the final with everything else hooked up
and see what would happen.  Does this sound safe?  Any suggestions would be
very much appreciated.  Thanks in advance.
Regards, John

John D. Littlejohn, W9NET
4 Brushmeade
Hollidaysburg, PA  16648
814-693-9767
jlittlej@mindspring.com
w9net@amsat.org