Dave,
I can remember just such confusion when I first heard the term
"GTO" which actually stands for gate turnoff thyristor, a complex type
of a triac/scr breed of power semiconductor.
Actually the term PTO is common to Drake and Collins as well as Ten Tec.
It is generic for Permeability Tuned Oscillator, They are easily made
linear in frequency to tuning ratio as in No. of turns / threads per
inch. They are mechanical in nature consisting of a vernier reduction
mechanism made of 3 ball bearings riding on a V shaped shaft.
This actually constitutes a slippable planetary drive turning a screw
mechanism which advances a ferrite core ( Slug tuning) into the vfo
coil. this in turn increases the inductance and increases the frequency.
This is been the main method of Vfo tuning in gear for some 20 or so
years, it works very well and has a specific "feel" to the touch.
Unfortunately it will as all mechanical devices require rebuild after
some 100's of thousands of cycles. Fortunately Ten Tec is able to keep
this design the same for all of their gear and can supply the "rebuild
kits" for peanuts. Actually some $30 dollars for a complete kit, quite
reasonable I think.
Hope that removes some of the mystique??
Archie K7ILZ
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