[Milsurplus] The BC-221N Freq Meter calibration.

[k2cby at optonline.net]

Guys,

If you're bound determined to bring a 1942 or so BC-221 frequency meter into
the 21st Century by generating a calibration book, at least make your job a
little easier.

Use either Microsoft Excel or one of the many clones available  on the
internet to store the results. Although I haven't downloaded it, there is a
ready-made BC221 spreadsheet available on the internet at
https://www.royalsignals.org.uk/files/221/bc221cal.htm.

Unless you already have a frequency counter, invest in one of the many
"cheap and dirty" counters available on eBay.

Couple the output of the BC-221 to the counter with a 100  pF  capacitor.

Fire up the BC-221 in the environment where it will be used, turn it on, and
let it sit there for 3 or 4 hours.

By the way, the calibration crystal can be "tweaked." On my 221 you access
the crystal trimmer by removing the nameplate on the front panel.

73,

/Miles, K2CBY

 

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