[time-nuts] HP10544A defective? Looking fro 10811

Howard W. Ashcraft hashcraft at hansonbridgett.com
Sun Apr 22 09:51:30 EDT 2007

I have been building a GPSDO around an HP10544A that I purchased on
eBay.  After some teeth-gnashing, I have concluded that the 10544A is
defective.  When attached to a load (it is supposed to be rated into 50
ohms) the frequency drops radically, and in fact, the frequency is
dependent upon load, never a good thing.  In addition, the output into a
high impedance load has strong collateral/noise signals that are
confusing downstream circuitry.  You can get a somewhat dirty sine wave
if you use a high-pass filter setting on an oscilloscope.  I took a look
on an SA and saw a fair amount of energy bouncing around 1.9 Mhz.

I am aware of the potential interference from the switcher heating
element and have isolated it with a LC filter, but to no avail.  Before
I see how big a dent I can create chucking this at the wall, I thought I
was see if anyone with experience with the 10544A thinks I'm missing
something.  In the alternative, does anyone have a 10811 they are
willing to sell before I start looking on eBay again?



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