HW-101 Warble Problem

[Jeffrey Weiss]

Hi, David and Jordan,

Thanks MUCH for the detailed information and suggestions on rebuilding the DARN
BLEEPIN VFO.

My first go-rounds last night--as I distracted the kids with a rental video of
the coneheads--were instructional
but not fruitful.

I discovered a missing screw on the little drive unit that bolts onto the drive
plate--not the jackson drive--and
replaced it.  Also crimped those tabs down. Until I remove the air variable I
can't get to the tabs on the jackson drive.

Short of removing the variable cap I disassembled the unit and reassembled per
the instruction manual, tightening screws/parts as specified and trying hard not
to introduce distortion. My efforts were perhaps inadequate and incomplete.

It's much worse!!! :-{  Every signal is now distorted and warbly. Aargh.

But that at least proves to me how sensitive the mechanical alignment of that
VFO is. So maybe tonight I strip it
down even further. To remove the capacitor it appears that the vfo box must be
assembled and perhaps some components unsoldered to get to some screws securing
the air variable.

And I will check that rear bearing/clamp of the air variable. I can try to
clean it and plunk it into a vise. And if that doesn't work,
I'll just keep on tightening the vise!

Anybody have the parts hotline number for Heath these days ;-)

Thanks again for all of your help, gentlemen!!

Jeffrey N0IRR

** Reply to message from "Kechkaylo, David" <dkechkaylo at MDSROC.COM> on Wed, 11
Nov 1998 16:47:52 -0500


> Dear Jordan:
>
> Yeah, from Dave K. here, thanks also for the input. Many of the VFO
> tuning caps used in the Heath VFOs (less expensive tuning caps) don't
> have a ball bearing adjustment there at the end of the rotor shaft;
> instead, this bearing is held onto the shaft end by the end of the
> tuning capacitor tub or shell, which holds the entire stator plates,
> know what I mean? The only way to add more force here is to clamp the
> tub shell down tighter from front to back with a vise, but carefully.
>
> Anyway, your suggestion is a possibility, too. I forgot about that.
>
> Dave Kechkaylo
>
> > ----------
> > From:         Jordan Arndt[SMTP:jordana at nucleus.com]
> > Sent:         Wednesday, November 11, 1998 4:34 PM
> > To:   HEATH at LISTSERV.TEMPE.GOV
> > Subject:      Re: HW-101 Warble Problem
> >
> > 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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