I've just pulled the trigger on an HP 53132A 225MHz Universal Counter that ought to cost me about £400 in total by the time I've paid VAT and clearance fees (It's coming from the US, I've just coughed up $448USD plus change). It hasn't got any of the fancy OCXO options but I'm not exactly short of OCXOs at the moment and the design of a board to substitute for the HP OCXO board isn't too onerous - there are already some designs out there.
Not as cheap-skate as I'd have liked (Keep quiet you lot in the back row seats) but most of them seem to go for more, a lot more if they've got any of the fancier timebase options - £600+ without fancy, £1000+ with, £1200 or more if they've got the 3GHz input as well (another relatively trivial add-on to make if I later find I need it). So I'm not feeling that I've let the side down
too much.
Much through I love my TTI TF930 it
is at heart a frequency counter, not a universal counter/timer and while doing the OCXO/GPSDO messing about I've found the lack of any decent time measurement facility has slowed me down a bit (no pun intended). The 53132A will do time measurements with 150ps resolution down to as low as 5ns and up to 100,000s. With that I can use the 53132A as an external instrument to qualify and characterise my GPSDO design rather than "marking my own homework" as I have been so far.
My difficulty has been not having had anything that can measure 1.000 000 000 seconds and be accurate on those last few digits representing nanoseconds to measure the phase error of my locally generated 1 PPS output. The TF930s resolution on that kind of measurement comes in at 20ns resolution for a 1 second aperture, 2ns for a 10 second aperture or 200ps for a 100 second aperture. The 53132A will better the TF930s 100 seconds best on a 1 second aperture and unlike the TF930 won't hide any errors in the 1 PPS signal by averaging it. The same story applies to the frequency realm, with the old TF930 having to do a lot of averaging to get enough resolution to allow me to get into the real nitty gritty.
Looks like my grip on the rim of this rabbit hole has got less firm. I'll see you all at the bottom.
Oh look, there seems to be some kind of sage looking Shifu rabbit down there. I wonder if he can tell me the
exact time?