[Hallicrafters] SX-101A selectivity

[Dave Moorman]

on 2/17/02 2:34 PM, Phil Atchley at ko6bb at elite.net wrote:

> This is 'usually' true but not always the case.  Some older silver mica caps
> suffer from silver 'migration' and can turn leaky or change value.  Also, it
> is not totally uncommon for the internal connections to some of the plates
> to open up, thus decreasing the overall value of the capacitor.  I have seen
> that in the RF section of a couple R-390A receivers that I overhauled.  When
> the mica capacitors went bad the set just WOULD NOT align properly with the
> result that the tuning slugs had to be tuned in too far (to compensate) and
> tracking of all the slug racks suffered.  Think I also saw it in a
> Hammarlund SP-600 receiver tuning turrent once.  And all the above named
> gear is "Mil spec"
> 
> 73 de Phil  KO6BB

Very true, Phil.  Have you had any experience with temperature coefficients
of LO capacitors changing over time?

Dave