[R-390] Cosmos PTO'S

[Pete Williams]

 G'day all....
I'm no  hot shot on these  but having done  about  30 over the  years  can
only offer  what I have  gleaned  and  applied from others  who have  been
this  way  before..
First, I  have never tried to calibrate  a Cosmos or  any other 'in situ'
 ----i,e in the  receiver. I went to the  trouble of using a dual HT
 supply and  separate   heater supply, getting the  appropriate
 connnector, and  treating the  assembly on the  bench.Output connected to
 a  counter of  course.
Secondly  resetability and ability to reproduce  a  previously documented
 setting is  difficult--- 'fraught' seems an appropriate  word.. Do the
math  and you will see that a  change of 1.406 degrees in rotation is a
shift of  390.625 Hz.!
As a minimum the setting measurement needs to be  precise and my PRACTICAL
 /realistic and achievable method is a  6 inch circular protractor mounted
on a PTO  shaft  connector  and an indicator mounted  as best possible to
correct for parallax  error.
 IF, repeat IF, you can set  and  reset to a  1 degree then good luck goes
 with you,or you have made yourself  an exemplary turning mechanism...... 1
 degree represents  277 .78 Hz.
I'd be happy to take  advice on more  sophisticated indicators  but  apart
from the purist approach, what I do  is somewhat better than  an
 'agricultural' approach via  mechanical system in the rx .....
The proof of the pudding is in the eating---- and  all my clients have
never complained of setting indigestion!.
Cheers
Pete VK3IZ



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