[R-1051] Frequency standard module

[Steve Hobensack]

My receiver comes on freq after a half hour warmup. I
calibrate my receiver while listening to wwv with two
speakers in the "isb" mode. I listen to the 600 cps
modulation ticks, and zero beat is fairly easy to find
while diddling the fine adjustment. I find that there
are about 32 turns endpoint to endpoint. If one hits
the endpoint, the coarse adjustment must be turned. 

I have found that the crystal will not zero beat if
the oven is cold or runs too hot. The oven temperature
can be adjusted to 85c by using a small lab
thermometer and monitoring the heater current with a
milliammeter. The current will suddenly drop to a low
value when the bridge circuit is balanced. This
adjustment is the small pot near the trimmers. Don't
mistake the pot for the piston trimmer. 
--- Geoff Fors <wb6nvh at mbay.net> wrote:
> Jan brings up a point I am curious about too.
> 
> Also, I have three R-1051B's and all of them are
> around 100 Hz off frequency
> from a cold start, but after warming up for say, an
> hour or two, they are
> right-on.   I don't like leaving 30 year old
> equipment powered up all the
> time when I am not around, so that initial
> off-frequency situation is
> annoying which requires using the variable frequency
> option on SSB signals
> for awhile.  I am curious how far off other people's
> receivers are from a
> cold start.
> 
> In the military, the sets were left powered up all
> the time, so it wouldn't
> have been an issue, and all of my receivers were
> originally slaved to an
> external standard anyway.
> 
> It would seem that the modern way to set your 1051
> standard module would be
> with one of those surplus HP GPS receiver frequency
> standards which are on
> the market from changes to cell phone sites.  The
> accuracy of the standard
> in the 1051 exceeds that of the average frequency
> counter.
> 
> Geoff Fors
> 
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