[time-nuts] ARRL FMT
Didier Juges
didier at cox.net
Sat Oct 28 04:08:10 UTC 2006
W4wj at aol.com wrote:
> Hi Didier...
>
> The "official" readings are taken for the band that is announced.
>
> Even though the exciters at W1AW are left on for an extended period of time
> before the test, there is some drift during the
> test period.
>
> I would suggest that you listen on 160 and 40 meters during the callup to
> determine wether you have a shot on those bands or not.
>
>
>
> If you are going to submit in the tenths of Hz, I would suggest that you
> only measure during the announced time for that band.
>
> Good Luck!!
>
>
> 73, Don, W4WJ
>
When measuring a single CW carrier, I would use the 3586A in direct
mode. Its counter has 0.1 Hz resolution, and it has an Ovenair OCXO that
has specs equivalent to the HP 10811 (2e-7/year). Unless I get my GPS
disciplined oscillator working by then, I'll be lucky if I am able to
calibrate it within 0.2 or 0.3 Hz against WWV at 10 or 15 MHz, that will
get me within 0.1Hz or so at 3.5 MHz. That should be a no-brainer.
Greater accuracy is probably not achievable because of atmospheric
variations, the rest will be luck.
I think I will run the 3586 set to WWV with my GPIB logging software for
a few days to see what kind of variations I get during the day and try
and find the best time to calibrate.
Also, we have the cal lab people (company called TMI) coming next week
as they do twice a year to calibrate a bunch of instruments on site
where I work. I am trying to find what kind of frequency standard they
have, but I may bring the 5370 and ask them to check the time base. We
have a bunch of microwave gear that needs to be calibrated to factory
specs, traceable to NIST per MIL-STD, so I would guess they have to have
at least a good rubidium or a GPS locked reference.
If I get my GPS working, I would try John's method. He has done a good
job documenting it. Unfortunately, while I have a bunch of machines
running Linux, they all run in the command mode, so I can't use the
graphical spectrum analysis software he is using :-(
Didier KO4BB
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