HW-101 Warble Problem

[Jordan Arndt]

Jeffrey Weiss wrote:
>
> Hi, David,
>
> ** Reply to message from "Kechkaylo, David" <dkechkaylo at MDSROC.COM> on Tue, 10
> Nov 1998 17:37:24 -0500
>
> > Dear Jeffery Weiss:
> >
> > Many of the ball-bearing type of Jackson Drives used in several of the
> > Heathkit amateur products had this problem from time to time. There may
> > be spots on the dial as you're tuning around and you won't hear this;
> > other spots (depends on the point you are on the VFO cap rotation), and
> > you can't seem to tune the station in, it warbles so bad.....it is like
> > your "pie-eyed" or drunk.
>
> Can this problem exist when you're ON a station and don't touch the VFO knob?
> It warbles for me, then.
> CW signals , most noticeable, pop up and down slightly in frequency about a
> center frequency while I'm sitting back and just listening.
>
> If it really sounds like the same problem I will happily disassemble the darn
> thing as you suggest. Cheap fix!
>
> Thanks,
>
> Jeffrey N0IRR
>
> >
> > Anyway, the problem is almost always a mechanical one here. Sometimes it
> > helps if you disassemble the VFO unit entirely, meaning the mechanical
> > VFO tuning capacitor from the VFO unit where it is mounted, the dial
> > assembly, and the Jackson drive unit. Then carefully put it back
> > together, but try to do this without any mechanical stress.....just let
> > the parts fit back together like they're supposed to...like a glove with
> > no forcing, according to the manual. No need here to get involved with
> > the electrical assembly, just the mechanical VFO capacitor drive parts.
> >
> > Once assembled, tighten the front tuning knob set screws associated with
> > the Jackson drive after you've rotated the main tuning knob back and
> > forth a couple of times to make sure this drive and the VFO tuning
> > capacitor shaft are straight in line. Then tighten the set screws. This
> > makes sure, if the VFO cap is off center, you won't warp the Jackson
> > drive a bit as you go thru all the possible tuning rotation. Sometimes
> > it helps to squeeze the tabs tighter around the collar of the Jackson
> > drive, too, as this may make the tuning a bit stiffer to rotate, but may
> > reduce some of the "slop".
> >
> > On the other hand, in difficult cases, direct replacement of the Jackson
> > drive cures the problem altogether. I hope this helps. The SB-104 uses
> > similar Jackson drives (actually two of them), and I absolutely HATE it
> > when the VFO warbles like that. The above explanation will sometimes
> > cure the problem on all Heath VFO units utilizing similar drive
> > mechanisms. If this solves your problem, then proceed to re-align the
> > VFO unit according to the manual. It won't be off by much, though.
> >
> > Regards,
> >
> > Dave Kechkaylo
> >
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In my experience the problem is not with the Ball drive but the rear
capacitor bearing... there is an adjustment but it needs to be cleaned
as it is the ground contact for the rear of the rotor plates... you
might get away with tightening the adjustment but it's safer to remove
the VFO and clean and or replace the bearing... it does tend to "Flake"
after some time... 73 de Jordan...

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