HW-101 VFO - Thanks to all!

[Paul K. Dean]

Just wanted to drop a note of thanks to all who responded to my plea for
help in getting the HW-101 vfo aligned.  I think we can all agree the
consensus is that the HW-101 vfo was not one of Heath's crowning
accomplishments!

I was aligning it according to the book, set the coil at the "high end" of
the band, which is actually the "low end" of the vfo, and the trimmers at
the other end.  A number of folks suggested reversing that order and one
quoted a former Heath engineer from a copy of the Heath Technical Journal
saying the same thing.  Well, tried it and wound up running out of trimmer
again, only this time with the screws in instead of out!  Appreciate the
suggestion none the less!!  Hey, we tried.  :)

What I ended up doing, after again checking and verifying component
physical layouts was to align it again, according to the book, but this
time at 050 and 450 on the dial rather than 000 and 500.  Well, after over
an hour of careful tweaking, I managed to get the error down to 7 khz (from
my previous attempt which netted me a 20 khz error).  Following that, I
split the error between the low an high end, giving me 3.5 khz off at each
end and progressively better towards the middle.  From the sounds of the
replies, I think I'd better consider myself lucky and stop there.  (Well,
the calibrator does work, that should help keep me in band.)

In addition to passing along my thanks, I also wanted to pass along another
intersting story on the subject related to me by Dave - WA6VVL.  Seems he
had a similar problem with a new unit some years ago.  He was kind enough
to give me permission to re-post his comments as I thought they might be
helpful to anyone going down the path that both of us have now gone
ourselves....... Albeit we did so nearly 25 years apart!

73, all and thanks again!
Paul, wb9hgz

Daves comments:

This is kind of like De Ja Vu.  I built an out of the box HW-101 s/n 08314
in early '74.  One of the many problems I had with it was VFO tracking.
Here is an exert from a letter I wrote Heath: "When the VFO was adjusted
between 0 and 500 on the dial, it was very non-linear and 20 KHz off at its
worst point. A fellow ham friend of mine owns an HW-100 and has similar VFO
problems.  We decided to set the VFO between 0 and 400 and let 500 fall
where it may.  As it turns out, 500 is about 15 KHz off and from 0 to 400,
linearity (tracking) is acceptable."
I also ran into a stability problem, part of the dial drive, where as you
loaded the bearings and slowly turned the dial one way or the other, the VFO
frequency would change/jump 100-500 Hz.  If this step was in the middle of
an SSB QSO, it would be impossible to tune in.
Heath NEVER resolved the tracking or stability problems with the HW-101's
VFO nor did they ever come up with any suggestions.  My letters went mostly
unanswered!!  The HW-101's VFO turned out to be the achilles heel with this
radio.  In desperation, I finally swapped the LMO out of an SB-300 parts
unit.  Absolute end of the problem except for the obvious problems with the
mismatch between the SB-300/HW-101 dial components.  But I left it this way
until I sold the HW-101.  The LMO's out of the SB-102, SB-300, etc. were
factory built and adjusted, so they worked out of the box.
Sorry that I don't have an answer for your VFO tracking problem, but at
least you're not alone.
73
Dave - WA6VVL

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