[time-nuts] Trimble Thunderbolt E frequency pulling.
GandalfG8 at aol.com
GandalfG8 at aol.com
Mon Nov 23 11:30:48 EST 2015
> Before I start probing any deeper I'd be interested to hear if anyone
> else come across this with the Thunderbolt E.
Is it thermal? Can you measure the frequency shift before it has time to
warm up?
--------------------
Switching the impedance at the counter itself resets any plot that's in
progress, which does introduce some delay, so I put together a small switch
box that could be inserted into the coax and confirmed it's a rapid effect
that's unlikely to be thermal.
It's even more observable with disciplining turned off and there's no
attempt to correct it, I can toggle back and forth between the two frequencies
just by switching the load.
One thing I did get wrong though when transposing my notes, switching from
low to high impedance at the 10Mhz output will increase the frequency,
with high to low decreasing it again, which is the reverse of what I originally
posted...whoops:-)
Nigel
GM8PZR
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