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

[Will]

Thanks for correction

Will

On 30/12/15 17:12, Bill Byrom wrote:
> 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
>>  
>  
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