[time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi

If you look at a typical BC-221 in use, it goes from “calibrated” in a nice warm hut to the back 
of a jeep. It heads out to an ice cold flight line and the switch turns the batteries back on again.
It bumps in and out of a batch of B-17’s setting each one up for the day’s net frequencies. You
would be doing very well to hold 50 ppm under those circumstances. That was indeed adequate
for the purpose.

Bob


> On Feb 12, 2017, at 7:58 PM, Bob Albert via time-nuts <time-nuts at febo.com> wrote:
> 
> Well 5 cycles per second is more than accurate enough.  That translates to a 150 Hz error at 30 MHz, definitely negligible for the uses of all these gear.  There was no official Time Nuts group at the time, although many of us had the spirit.  Yet the capability of the BC-221 far exceeded its specification if you could receive WWV.
> 
> I noted immediately that zero beat of WWV at 5 MHz was not as precise as at 15 MHz.  In those days there was even a 30 MHz WWV but it got shut down a long time ago.  And there were CHU and JJY.
> 
> Bob
> 
> 
>    On Sunday, February 12, 2017 4:02 PM, Dan Rae <danrae at verizon.net> wrote:
> 
> 
> To put BC-221 things in perspective, the 1 Mc/s reference crystal was 
> adjusted, according to the manual, to within 5 c/s...
> 
> Things have come a ways since!
> 
> Dan
> 
> 
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