[SignalOne] Restoring a badly bruised CX7A

[Peter Sundberg]

Hi,

I am trying to restore a CX7A that a friend of mine bought at a 
fleamarket a while back. The radio was dead when he bought it and it 
was in really bad shape. Who ever worked on it did not know what he 
was doing and without doubt made more of a mess rather fixing it.

I've documentet some of my work and will continue to do so, see 
https://www.sm2cew.com/CX7A/CX7A.html

Present status, in short:

The radio is still not working fully.

- main issue, both VFO's are dead, not giving any output

- new AF chip is working well and there is noise coming out of the speaker

- dual channel produces noise that can be varied in respect to VFO A or B

- the IF sections seems to be ok, injecting an 8.8 MHz signal at the 
filters gives nice audio out and AGC action. AGC fast/slow is working

- RF board crystal oscillators are working

- CW sidetone, key and BK-in is working. No RF signal out of course 
at this point.

- when pressing A/T.O. the spot tone is heard and can be varied in 
frequency and the spot level is working. It sounds like the missing 
SPOT button is activated at all times

- IF shift appears to be working when listening to the change in 
audio when turning the knob

- LSB passband noise seems to be ok, USB is very high pitch


As I know there is a wealth of knowledge among this group I would 
like to hear some ideas as to why both PTO's have gone dead. They 
both have +/- 15 volts on the correct pins. Any suggestions what 
devices can be used replace the original transistors in the PTO's?

And also, does anybody know where I might find a source for the 
pushbuttons that are missing (AC and SPOT)

As I have an older fully working CX7 of my own (made in Florida) so I 
have a service manual, which is of good help of course. I'll keep 
working on this CX7A as I think it is a much too fine radio to end up 
in a dump somewhere :-)

But any help or hints along the way from you guys will be much appreciated.

73
Peter SM2CEW