[R-390] PTO Linearity

[Flowertime01 at wmconnect.com]

Just out of curiosity, Roger, what was considered acceptable linearity for 
working radios, considering that the factory spec was 300 cycles?

Ed,
--------------------------I
Ed,

We would not even try to tweek the end points if it was off less than 3 Khz. 
As far as linearity went, if you could get a cal tone to zero on the 100 KC 
within reach of the zero adjust it was good enough. Hay we were fighting a war 
abet a cold one.

We only checked the total spread end to end. If we could not get a fair end 
point adjustment, we sent the critter to depot exchange. We never tried to get 
inside one. You could still get brand new units from the depot, who would ever 
want to fix one? 

Most of them were pretty good within the 300 Hertz factory spec. We just 
expected them to be linear and that was that nothing to inspect or test. The flip 
side was every shop did have a budget. We were putting hours on tubes 24 7 and 
needed lots of them. The teletype guys were also eating motor brushes, 
printer ribbons and paper. We would not go looking for items to change. We had a 
fairly loose 10 : 1 signal to noise ratio and did not work over time eking the 
extra out of receiver. We hated to give the operators real great receivers, they 
expected them to all work that well. We could spend time doing cleaning and 
alignment, theses were just time consuming and did not cost extra for parts. We 
were going to be on the bench for the hours so we did what we could with the 
time and tools to give the best we could for the operators. PTO were pretty 
linear and not worth the effort and cost over head to swap out.

You just were not going to tell the Warrant Officer you were dead lining a 
R390/A and wanted a PTO because the operator would have to zero it every 200 kHz.


Roger KC6TRU