Eddy -
The Carrier Oscillator is shifted in frequency by about 900 Hz in the CW position. This is
accomplished by putting a capacitor (C177) in series with the ground end of the CO crystal. The
MODE switch shorts this capacitor to ground in SSB and TUNE position. So certainly a poor switch
contact could easily shift the frequency anywhere from 0 to 900 Hz or so depending upon just how
well it shorts that cap.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Eddy Swynar wrote:
Hi Again All,
Well, to-day I could have SWORN that some demon had taken possession of the PTO in
my T-4X transmitter,& that it was sent to this earth with the express purpose
of taunting me...!
I mentioned before that last week I re-soldered a visibly bad connection of the 33-pfd. temperature compensating
capacitor to the board of my PTO, and that---so far!---it appeared to be the proverbial "silver bullet" in
fixing the "warbling". Well, this morning---at the very moment that I was seriously considering taking the
"4-Line" on a road trip to the cottage to test the PTO "in the field"---the frequency suddenly
jumped a coupla KHz, and was raspy-sounding...!
Oh no, here we go again! ("Why do the gods taunt me so...?!").
Turns out---I think!---that I was monitoring the T-4X with the function switch in the
"Tune" position. By wiggling that switch ever-so-slightly, I could make the
frequency jump a prescribed amount of KHz----exactly the amount that I get when switching
the mode switch to Phone.
I wonder if a dirty mode switch may have contributed to my initial confusion in
this whole matter...?
The testing continues...
~73~ de Eddy VE3CUI - VE3XZ
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