[TenTec] Paragon II transmit troubles

[Ken Brown]

     Yesterday I tried to use my Paragon II for the Straight Key Night 
operating event. I have mostly used it just for receiving, because it is 
general coverage and has AM mode. My Omni VI was my primary QSO making 
rig. When I got the Paragon II all hooked up and ready to go, I got a 
few seconds of transmit power out, and then it quit working. 

Here is a list of the symptoms:

     Plenty of RF carrier power in FM and AM modes.
     No RF power (or at least very little) output in Tune or CW modes.
     Some RF power output in one of the SSB modes, but it seems to be 
mostly a constant carrier hardly affected by microphone audio input.
     RF PWR control does control the amount of TX RF out in FM and AM modes.

     I am thinking the problem is in the balanced modulator on the 
TX/Audio BFO board. The TX carrier for FM and AM follows a separate 
path, which is apparently still functioning. It seems that the variable 
attenuator D20 and D21 on the Second Mixer board, and everything 
subsequent to that are working fine, based on the fact that FM and AM TX 
carrier seem to work fine.  There are a number of other switching diodes 
which the CW and SSB TX signal must pass through, which could also be 
not working, either because of a failure in those devices or a failure 
in the control signals that switch them. A failure of Q9 or Q10 on the 
Second Mixer board could also do it.

     I have already cleaned and exercised all of the connectors on all 
of the boards, and tightened the screws that hold the boards in place. I 
guess I'm going to have to start probing around with a multimeter and/or 
scope to see what is working and what is not. Or I could just reflow 
solder connections on both the TX/Audio BFO board and the Second Mixer 
board. Maybe I should change out every electrolytic capacitor on those 
boards.

     Has anyone out there experienced a similar problem with a Paragon 
II and if so what was the cause and the solution?

     I did not make it on the air for SKN. Maybe next year.

73 ES HNY DE N6KB