[Boatanchors] R-390A selector problem

[Bob Young]

On my Motorola 390A I have an intermittant problem: with the 4,8 and 16 KHz 
filters the sensivity is good, when I switch to 2,1 and 0.1 the S meter 
drops about 50 db with corresponding volume loss. This is intermittant 
however as it will sometimes work evenly on all 6 positions. It does not 
seem to be a mechanical problem with the selector switch itself as moving it 
does nothing usually and there is no noise when it is switched, sometime a 
strong signal will jar it back to normal volume however when it is in the 
tighter positions. the 2 Khz mechanical filter and the crystal filters all 
seem good. Related to this, where and what is is the killer cap that will 
take out the mechanical filters if not replaced? Thanks again,

Bob Young (who no longer uses implements of destruction on 390's and/or 
390A's
Millbury, Ma
KB1OKL