[Heathkit] SB-102 LMO

[Mike Hyder -N4NT-]

Hi, Glen--

I built an SB-102 and used it a long time.  I don't recall it being off in
the mid dial readings.  I also owned the SB-313 (I think the model was, it
was the shortwave solid state radio that matched the SB-102) which I used as
an external VFO for the SB-102.  I don't recall that receiver having the
problem, either.

What I would not do is to mess with the divided plate in the capacitor.

What I would try is to align the VFO so that it lined up at the 100 and 400
dial settings instead of the ends.  If that doesn't give you satisfactory
results, then change the setting so that the capacitor is not tuning over
the same physical range.  For instance, if you are starting with the
capacitor fully meshed just past one end, then change your starting point so
that the capacitor when almost fully open is beyond the other end.  I
wouldn't imagine that the capacitor uses its whole range from full mesh to
full open, so I'd want to try using the center of its range.

73, Mike N4NT

----- Original Message -----
From: "Glen Zook" <gzook@yahoo.com>
To: <heathkit@mailman.qth.net>
Sent: Sunday, June 23, 2002 11:08 PM
Subject: [Heathkit] SB-102 LMO


> I am in the process of trying to get an SB-102
> repaired for a friend and the main problem is the
> solid-state LMO.
>
> I now have available a total of 5 LMO units, of two
> different physical layouts, but are for the SB-102.
> All five of them when the "end points" are "on" (that
> is exactly 5 revolutions goes from 5 to 5.5 MHz) the
> intermediate 100 KHz points are off from 3 to over 10
> KHz depending on the individual LMO.  This has been
> checked both with a frequency counter and in the unit
> itself "on frequency" (i.e. 3.5 - 4.0 MHz received).
>
> Now, nominally, Heath LMOs are well within 1 KHz at
> the intermediate 100 KHz points.  At least this is my
> experience with the tube type units.  However, my
> experience with the solid-state LMO units is minimal
> (have worked on numerous tube-type LMO units).  Since
> this trait is the same on 5 different units, I am
> wondering just how close the "tracking" is normally on
> the solid-state LMOs.
>
> The physical differences between the two types is
> considerable.  Primarly the only things common are the
> tuning shaft, the 3 terminal power strip, and the
> ridge for mounting the upper portion of the dial
> assembly.
>
> Frankly, since all 5 units show the same type of
> problem, I am really wondering about the tracking
> ability of the solid-state LMO units.  Of course
> Murphy never takes a vacation, but it is strange that
> 5 different units have the same problem.
>
> Any ideas?  Any suggestions as to how to get the
> frequency to track closer (yes, I know that the
> slotted variable capacitor plates can be adjusted - a
> real pain!).
>
> Glen, K9STH
>
> =====
> Glen, K9STH
>
> Web sites
>
> http://home.attbi.com/~k9sth
> http://home.attbi.com/~zcomco