[R-390] A bug and its fixing under way

[Roy Morgan]

On Aug 3, 2009, at 8:09 PM, Jim Haynes wrote:

> I have an R-390A that was making a lot of popping and crackling noise.
> Traced it to the inductor in the plate circuit of the 1st IF
> amplifier, which seemed to be going open intermittently.

Out, OUT, damned inductor!
(Apologies to McBeth)


> ...  I've ordered
> a few 12 mH chokes so I can replace it and hopefully fix the problem.

Are they twelve millihenries?  (I've not replaced any, yet, and don't  
have the parts list at hand.)

> While I was working on this I noticed the crystal oscillator output
> is low.

Did you measure it at the oscillator test point?  With an isolating  
resistor at the probe tip as in older VTVM's?  A modern DMM test lead  
will load down the oscillator and give you a low reading.

Is it low on all/many bands, or just one or two?

Roy

Roy Morgan
k1lky at earthlink.net
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Groton NY, 13073
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Cell: 301-928-7794