I believe you meant a BC-221 frequency meter, which was a very good instrument when introduced over 70 years ago:. http://radionerds.com/index.php/BC-221 http://www.orionsword.net/Electronics/TestEquipment/ZenithFreqMeter/BC221.html
Back in the early 1970's I took my BC-221 and added a TTL divide by 1,000 (or 2,000 or 4,000 or 8,000) external circuit to generate very precise audio test tones from the RF oscillator. The BC-221 had two output frequency ranges: LOW: 125 to 250 kHz HIGH: 2 to 4 MHz By using the appropriate range and divide ratio I could generate 15.625 Hz to 4 kHz (and multiples) with very smooth continuous tuning and great accuracy (typically better than 0.005%). This was very useful for adjusting and measuring audio filters and circuits, such as 2125/2295 Hz AFSK terminal units I was using on 2 Meter AM and with SSB rigs for HF FSK. I could tune up my filters built with 88 mH telephone surplus toroidial inductors. I could also use the audio source to compare by ear the beat note between harmonics of my divided-down 5 MHz commercial surplus precision oven oscillator and RF signals (such as during the ARRL Frequency Measuring Test). The anti-backlash gear mechanism, large dial with high resolution interpolation scale, and well-built variable capacitor were difficult to find in other commonly available radio related equipment. In my opinion the BC-221 was a technically beautiful precision instrument. It was the time-nuts tool of choice for several decades! -- Bill Byrom N5BB On Tue, Dec 29, 2015, at 08:12 PM, Will wrote: > > That sure beats a BC21 that many hams (and Post Office Techs) used long > ago. > > So long ago Google doesn't want to help and memory has faded over half > a century. > > Cheers, > Will > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
