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Old June 1st 08, 01:52 PM posted to rec.radio.amateur.boatanchors,rec.antiques.radio+phono
COLIN LAMB COLIN LAMB is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 241
Default How linear are Heathkit SB series LMOs?

Hi Dave:

First, let me say I have not played with the Heath LMO alignment for decades
and
I do not remember specifics. But, here are things I would do - not
necessarily in order.

1. Draw a graph of the LMO error so that you have a visual representation
of the error. It may be that the error is simply occurring at one end,
which could mean that a mechanical shift of the plates could accomplish your
goal.

2. Most capacitors in receivers generally have tabs on the outside plate
divided into sections that can be bent to facilitate adjustment. You
sometimes can make minor physical admustments even without the plates that
are divided with slots.

3. A trick to reduce the end error is to align for a point in from the end,
such as 3.6 and 3.9 MHz. Track the error. Then, try 3.55 and 3.95 and
track the error. You might be able to find a compromise you can live with.

4. You can physically take a Dremel tool and custom shape the outside rotor
or stator to give you the curve you desire. This requires careful
documentation of the shift. A computer graph made by a spreadsheet works
great.

With patience and care, you should be able to get it right on the button.

73, Colin K7FM