On Thu, 2009-01-01 at 17:46 -0600, John Cox wrote:
> Hi Jerry
> I would say that it is probably not the mechanical part of the PTO. If It
> is the rebuild kit which is a good thing to buy while it is still available
> will probably not help since it just replaces the grease and wear parts in
> the drive. I would think that taping on the tuning knob on any Ten-Tec PTO
> of this type would cause a frequency shift since you are moving the screw
> drive when you do that. Now if you are really banging on the key when you
> send that could be another story =:-)
The drive is spring loaded but when the vernier balls and race wear, the
shaft develops end play and the PTO isn't far from the internal speaker
that makes noise for side tone while sending CW too.
> I would look for something heat sensitive in the circuitry common to the
> receive and transmit oscillator frequency generation.
Which is every crystal and the PTO.
> I would see how my
> Omni C reacts to taping but I blew the final transistors while testing after
> rebuilding the PTO I accidentally turned the band switch while key down
> which is a no no. I still had the front panel off and got confused.
> 73, John
> KC0YAI
And I know from working on mine that the PTO parts do wear to make it
loose. Because of the spring loading the PTO sensitivity to vibration
varies from one end of the band to the other. A really worn PTO will
slip, more at the low end than the high end of a band. Because the
spring tension is higher at the low end.
Something else to check is every internal cable, especially those
supplying power to oscillators. Pins often respond to a bit of motion to
clean, but stay better with a quarter drop of DeoxIT from Cramolin
applied to each pin.
73, Jerry, K0CQ
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