[R-390] PTO

[DJED1 at aol.com]

Well, I never did it for a living, but here's my  understanding of how to 
align the PTO. Incidentally, the experts say it is  critical to get the PTO 
correctly aligned with the geartrain, otherwise the gain  suffers a lot.  You need 
to be within a few Kc to get good  performance.
I just went through this alignment after consulting the  archives:
1. First, set the overrun on the dial so it's symmetrical at about  35 Kc at 
top and bottom of the band. 
2. Center the zero adjust, then  don't touch it.
3. Set the PTO end point to within 2 or 3 Kc.
4. Set the  radio to 7.000+ (that is 8.000 on the 7 Mc band)
5. Loosen the Oldham coupler  at the front side, set the PTO to 2.455, then 
tighten the coupler.
The PTO  should now track correctly with the rest of the radio.  This assumes 
that  the radio geartrain is in correct mechanical alignment to start.

If you  don't have a frequency counter, and the PTO is close to correct, you 
can use the  calibrator to do step 5.  Loosen the coupler, turn the PTO by 
hand until  you zero beat the calibrator signal, then tighten the coupler.  

Ed  




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