More SB-101 Help?

[Kevin J Ward]

Dave -

A red flag for me was your statement that the crystals for 21, 28 & 29
MHz wouldn't start.  Crystals don't usually fail en masse.  I would
suspect a problem with the oscillator circuit.  The 20 KHz frequency
error points in the same direction.  Mistuning of an oscillator can
sometimes pull the crystal frequency a lot.  In fact, a broken slug can
cause erratic problems, and it's quite possible that you didn't break it;
 it could have been broken before you got the radio.

One way to remove a broken slug is to epoxy the broken pieces to the end
of a broken twist drill of an appropriate size.  What?  You don't have a
broken twist drill; I thought hams saved everything.  Never mind.  Cut a
chunk out of an old coat hanger (they come in various thicknesses) and
bend one end into an "L" like an Allen wrench.  Sand off the coating on a
half inch of the other end, so the glue can get a good grip on the metal.


Mix up just a tiny bit of two-part epoxy and coat the sanded end of the
wire.  Be careful not to touch any part of the inside of the coil form
with the glue during the next step.  Use two hands and something to brace
them on, and carefully insert the glue end into the broken pieces of coil
slug.  Twist the tool a bit to "shmooey" the glue so that all the broken
pieces will be captured.  Clip an alligator clip (use the clip only, no
wire attached) to the makeshift tool, just above the top of the coil form
so that the clip will rest on the top of the coil form, then let it sit
undisturbed for several hours to fully cure the epoxy.

The last step is to CAREFULLY remove the slug and tool from the coil
form.  Paper coil forms are usually slathered in beeswax to keep the
slugs from moving.   Here's a tip to make removal easier.  Hold the
business end of a soldering iron or gun near the coil form (no closer
than a quarter-inch) long enough to soften the wax, then turn the slug
out before the wax hardens.  This trick can also be used during alignment
and will prevent breakage in the first place.

I keep a lump of beeswax at the workbench for tightening up loose slugs.
Use a pen knife to shave a small bit of wax on top of the loose slug,
then carefully heat the form as before.  In all cases, keep the iron from
actually touching the coil form.  And never, ever use candle wax.

You indicated you had been through the alignment procedure.  Visually
check coil slugs to make sure none of them are completely out of the
winding area.  If you find one that way, turn it into the center of the
coil and try the alignment again.    Enough said.

Good luck.    ;)

Kevin  N2IE

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