[time-nuts] Abstract for consideration at 2016 New Mexico TechFest

[Bill Byrom]

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
>