[Milsurplus] LM freq meter calibration book accuracy

[C.Whitaker]

de WB2CPN
The Cal Book only calibrates the variable capacitor,
the coils,and whatever other wiring that connects all
this together.  The book is written after all the electronic
parts are assembled, and warmed up.  They had a
little machine that turned the LM (221) dial, measured
the frequency, and printed the book.
Old-time automation.
There is a video of this someplace.  I saw it.
Once the crystal is properly adjusted to its marked
frequency the book should remain accurate.  The
book's calibration depends on the crystal being
adjusted, and not much else.
That's why the books stay good forever, or a long
time like that.
Not listening to the Instruction Manual, but the
crystal can be adjusted by setting the dial to a
WWV or similar frequency you can depend on,
setting the little knob to the middle, and adjusting
the crystal for a Zero Beat.
EOT
73  Clete

On 7/28/2013 8:28 AM, Mark wrote:
> A few years ago I picked up a VERY nice LM with its original cal book and a matching Navy ACPS.
>
> It was priced so low I couldn't resist. I was going to gut it and use the cases but good sense prevailed and I plugged it in.
>
> I was astounded at the accuracy of the cal book. Spot on many decades after it was made.
>
> Stickers indicated that it was owned by Douglas Aircraft and in use until at least 1970.
>
> Needless to say I didn't gut it. I love using it with my BC 348 and ARR 15.
>
> Sometimes WW2 mil surplus radio gear soldiers on a lot longer than you'd expect. Witness the RAF's use of the APS 20 radar into the early 1990s on Shackleton aircraft.
>
> I worked at Hughes and we made lots of mil radar gear. One of our engineers got to ride in a Shackleton and operate the ancient APS 20. He was completely amazed at how well it performed.
>
> Mark
> AF6IM
>
> It's obsolete and outperformed by the cheapest digital counters, but I love using it with my BC 348.
>
>
>
>
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