Heathkit SB Line Dial Drive Assembly

Edward Swynar VE3 CUI gswynar at DURHAM.NET
Tue Mar 23 16:16:41 EST 1999


Don't flip yer lid just yet!

That front panel / eschutcheon mounting hole behind the main tuning knob on
the SB-series is not round for good reason: before you spend another dime,
or otherwise do something rash, remove the main tuning knob, lightly loosen
the nut holding the drive assembly to the escutcheon (that's LOOSEN! DON'T
remove the  nut!), and apply gentle downward pressure on the drive...

Now, re-tighten the nut, re-install the knob. If it STILL slips, repeat the
process. If it continues to slip with the drive unit as far down as it'll
go, you'll have to remove the drive from the rig (lotsa work!) and
"re-build"  it by removing the two copper flange wheels (held on with a
screw at the end) and installing curved washers on the outside of both to
increase friction.

Either way, you're compensating for the "relaxation" of the flanged drivers
over time. The situation is serious, but certainly NOT hopeless!

Good luck & 73, de Eddy VE3CUI - VE3XZ

> From: Rick Parent <rparent at sky.net>
BASWAPLIST at foothill.net; heathkit at qth.net; boatanchors at theporch.com
> Subject: Heathkit SB Line Dial Drive Assembly
> Date: March 22, 1999 10:13 PM
> Hi Gang...
>             Been away for awhile.....OOOoohhhh 25 years or so. Built my
> share of "greenies" when I was younger and never remember having a lot
> of trouble with dial drives on SB's. Had a 101 and a 102. I remember the
> dial drives being pretty smooth, considering their makeup. Recently,
> I've decided to get reacquainted with this addiction of ours and have
> bought a 300, 400, and a 101 in the last couple of weeks. ALL THREE have
> the dreaded "Dial Drive Disease"!! Looks to me like the dial drive
> pulley (#100-444) is just spinning (with the knob - of course) and not
> making contact with the Dial Drive Ring (or Circular Dial Plate Assembly
> #100-M449). I'm guessing this because I haven't actually pulled any of
> the front panels. Just been squinting behind the panels, with a
> flashlight, looking down the front side of the chassis trying to figure
> out why the hell the numbers aren't moving 'round anymore! Am I all wet
> here? Is there something I'm missing? Or am I just incredibly lucky to
> have gotten three examples of shoddy assembly practices? Would think
> that this has got to be a really common problem, since I'm batting 3 for
> 3! Anybody have a source for these parts? I'd really like to get my
> hands on the "whole bag" of goodies (#100-M450 - Dial Drive Assembly).
> I'm thinking that there's a real opportunity here to made some money
> going into production!
> Also looking for the AM Filter (#404-201 - 3.75khz), FL3, for an SB-300.
> Thanks & 73's!
> Rick Parent,  KA1GBJ
> rparent at sky.net

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