[Hallicrafters] sx-100

[Kenneth D. Grimm, K4XL]

----- Original Message ----- 
From: "Jerry Watkins" <jw at wk.net>


hi everybody, my progress is going slow. have fixed problems and more
arrise. i guess thats the way it goes. my audio problem, im sure will be
fixed with a transformer.i have very little or no signal on three bands.
but on 4.6-13 mc band, was working good , but now intermitent .and has
motorboating. i have a feeling it is a tube or tubes.my tube tester i
dont think is very reliable. it is an old lafayette. but i am thrilled
to see it work this much  any sugestions?  jerry watkins   n4tbu



To quote from Marcus and Levy:  "The most common cause for motorboating
is an open output filter capacitor in the power supply.  The only other
common cause is an open grid circuit in any of the stages of the
receiver.  A servicing procedure for this defect in the receiver is to
bridge the output filter capacitor in the power supply with a test
capacitor of similar capacitance and to see if the trouble is
eliminated.  If this proves ineffective, the technician proceeds to make
an ohmmeter check of all grid circuits, looking for an open.  In this
regard, it should be remembered that agc decoupling filter resistors are
part of their grid circuits.  They must not be overlooked, even though
they rarely open.  The most common opens occur in the grid-load
resistors of the first and second a-f stages."
Hope this helps you locate the cause of the motorboating.
73,
Ken K4XL
k4xl at arrl.net
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