Heathkit SB-Series Dial Slippage...

[Edward]

Many thanks to all you many supportive Heath fans who took the time &
effort to comfort me re. the dial slippage / backlash problem with my
otherwise excellent SB-300 receiver...

I've fixed the problem---my experience in the round about way I did it may
help others, AND warn you as to how NOT cure it!

The dials in the SB-rigs slip when the 2 flanged, copper-coloured friction
wheels at the end of the main tuning knob become too spread out vis-a-vis
one another (the more spread apart they are, the poorer the grip on the
dial, & the more slippage). ARRL's Hints & Kinks has several "fixes" over
the years (at least one of these is quite bizarre). The best cure is to
eliminate / reduce the spacing between the 2 coper washers, PERIOD...

My theory to execute this was sound: I removed the outside washer, &
mounted it on a ratchet socket, the outter lip of which just fit nicely
INSIDE the formed flange of the washer. Next, I secured a SMALLER ratchet
socket that just fit nicely on the washer body INSIDE this same lip.
Placing the whole affair on a solid foundation, I then lightly struck the
small socket downward with a hammer (the idea being that my peaning would
re-deepen the flange of the worn washer).

I checked the fit several times while doing this, but neglected to take
into acount the octagonal forming of the smaller ratchet"punch press
die"---the edges cut into the washer material after I struck it once too
many times, and actually split the metal in the form of a half-octagon,
absolutely ruining it!!!

What to do...? I secured one of those thin metal wahers that Heath used
between the main front panel & the nut of its controls---these are EXACTLY
the same diameter as the copper friction drivers. I placed it atop the
original, unremoved & "...still-on-the-drive-assembly" second driver /
washer, placed a smaller washer atop this washer (with the proper sized
hole to accomodate the screw that holds both washers together), and
soldered this same smaller washer to the "new"one.

PRESTO! Even though this new second washer / driver isn't flanged, the
first one still is, & the dial will fit into the assembly with little
effort. You'll find that it does not need to be slipped over the dial all
that deeply, either, because the bulk of the spring friction now comes
primarily from the one original washer alone...

If I work you tonight / tomorrow on the occasion of the "AWA 1929 QSO
Party", it will be with the SB-300 receiver here with this very fix...!

Tnx agn to all & 73, de Eddy VE3CUI - VE3XZ

--- --- --- --- --- --- --- --- --- --- --- --- --- --
To subscribe: listserv at listserv.tempe.gov
and in body: subscribe HEATH yourfirstname yourlastname
To unsubscribe:  listserv at listserv.tempe.gov
and in body: signoff HEATH
Archives for HEATH: http://www.tempe.gov/archives
--- --- --- --- --- --- --- --- --- --- --- --- --- --