[R-390] BFO Question

[Drew Papanek]

John Flood wrote:

<snipped>

>My early 60's vintage Amelco R-390A has bfo trouble.  It would generate a
>signal  but the frequency sounded high (sorry did not measure it) and there
>was very little adjustment with the dial.  A tube swap did not help and
>looking at the drawing and being dangerous as mentioned above, I thought
>that there was not much that could be wrong there other than the little,
>pto I think, bfo can.

The BFO knob has a tab providing a robust end of travel stop for BFO shaft.  
If knob is installed too far out on shaft, tab is non functional and it is 
possible to turn several revolutions.  BFO can provides no real stops; 
forcing at end of travel will easily break BFO tuning slug partially or 
completely.  This may be your trouble.

Remove and open that can despite those warnings which simply goad you on!  
Make a note of wire connection points.  BFO slug/shaft can be rejoined with 
great care and sparing use of epoxy.

>A new one just arrived from Fair Radio and thus
>generates, pun intended, my question.  The shaft on the new bfo can is a
>bit stiff not easily turned by fingers.  There seems to be a bit of
>oxidation on the shaft bearing.  Is it OK to put a drop of oil on it
>without risking damage of some type and if so what is the official BFO lube
>approved by the list?  I certainly don't want to get blacklisted for using
>solid-state lubricant.

Oil won't hurt.  A lubricant prized by many list members is Mobil 1 
synthetic motor oil.  It does not gum up as some others do.  Fair Radio is 
very good about customer satisfaction; you might consider returning the unit 
for another replacement.

Drew


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