[Milsurplus] [Boatanchors] BC-348 E-M-P

[J. Forster]

That tells you exactly what the problem is. The tolerances were out for
the press fit, causing an excessive hoop stress in the hex nut. A worn or
reground drill bit on the screw machine is likely the root cause.
It eventually fractured.

-John

===============


> In all cases I have found the capacitors to be free of corrosion and the
> exposed shaft bright and shinny. Examining the hex sleeves, I have
> typically
> found a single hairline crack running parallel to the shaft axis. Once the
> hex nut loosens, the three prong spring moves the rotor until the plates
> meet and short with the stators.
>
> John  WA4WDL
>
> --------------------------------------------------
> From: "John Hutchins" <jphutch60bj at gmail.com>
> Sent: Friday, May 13, 2011 8:52 AM
> To: <milsurplus at mailman.qth.net>
> Subject: Re: [Milsurplus] [Boatanchors] BC-348 E-M-P
>
>> Dennis, Joe
>> "After trouble shooting I found that about 5 or 6 of the 30 or so
>> alignment APC trimmer caps located in the Ant,RF,Det and Osc boxes had
>> shorted. They had slipped on the shaft someway and shorted the plates
>> together."
>>
>> Slipping shaft - I do wonder how the plates could move;  Could it be
>> corrosion buildup, pushing the shaft?
>> Any how thanks for the detailed analysis,  Something to look for.
>>
>> Hutch
>
>
>
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