[time-nuts] HP 5071A Electron Multiplier of Cesium Beam Tube
jmiles at pop.net
Mon Sep 7 23:46:46 UTC 2009
> > It's an HP 3048A. I have long held vague ambitions toward
> > replacing it with a homebrew digital system but it hasn't happened
> > yet.
> > john, KE5FX
> Thanks, John. You have a fortune in first-class equipment!
Thanks -- this stuff is all pretty cheap if you wait by the eBay river long
enough. It is more important to have an understanding S.O. than a large
equipment budget (the 3048A occupies a 6' rack in what amounts to my living
> The -105 dBc/Hz at 1Hz looks pretty good. Is that measured with the
> internal reference in the 11848A? Or can it even get down that low
> at 1Hz?
The reference was a surplus 5 MHz Wenzel ULN. It is rated at -115 dBc/Hz at
1 Hz, so was sufficient for these tests. The 11848A's 10 MHz sources have a
good broadband floor but are not very stable close-in due to their wide
The actual measurement is here fwiw: http://www.thegleam.com/ke5fx/cs.gif
> If not, I see from your web site you have a Wenzel 80MHz ULN. Did
> you use that for the reference? If so, did you ever find out what
> was causing the ~10dB excess noise in the regenerative divider...?
I'm waiting until I have faster digital noise analysis capabilities before
tinkering with the regenerative divider any further. They need a lot of
tweaking to perform at their best, rather than being the plug-and-play
devices that I originally expected. The results on that page should be
treated as provisional.
-- john, KE5FX
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