[SignalOne] The CX7A Lives!

[jerry]

Just a little.  I have upgraded the power supply to three-terminal 
regulators.  It had a fault with the T/R switching that was driving me 
nuts ... all due to the 5V regulator.  I had neglected to bypass it, and 
it was oscillating.  An SMD .1uF across the input fixed it right up.

Now it receives.  Both PTOs work.  The crystal calibrator works.  How 
old fashioned!  A digital-readout rig with a crystal calibrator!  I 
haven't installed an audio amplifier yet.  The original one had shorted 
and let out its smoke.  I hooked up the low level audio to the "patch" 
connector on the back panel.  And plugged in a Soviet-surplus 
high-impedance headset left over from a crystal radio project.  The S 
meter works.

It also transmits.  A little.  I am getting 50W out in "tune" on 40M.  
Nothing on any other band.  There is no displayed screen current.  And 
no displayed "drive", either.  It also transmits CW with my Vibroplex 
bug plugged into the EXT KEY jack.  The keyer works, but I need a 3/16" 
plug for it.  And I just got the radio to transmit SSB!

If the tube is tired, I have another one.  But I don't think that's the 
problem.  Pretty sure that the "drive" metering is before the tube.

Given that there's output on 40 but no other band, it might be that 
somebody "golden screwdriver'd " that transmitter into oblivion.

   I am thinking about what audio amp to put in.  LM380?  TDA2030?  I'd 
like to get one clean watt out.  I have not populated a 24V regulator 
yet.  As far as I can tell, that's only used for the audio amp.  So I 
can choose the voltage.


                      - Jerry, KF6VB