From: Bruce Griffiths <[EMAIL PROTECTED]> Subject: Re: [time-nuts] HP 5370B Date: Sun, 11 May 2008 00:15:34 +1200 Message-ID: <[EMAIL PROTECTED]>
> Magnus Danielson wrote: > >> Mark, > >> > >> The 5335 is specified at 9 digits/second of resolution, the 5370 is > >> specified at 12 digits/second. > >> > > > > That is severly overoptimistic on the 5370's part and just about > > overoptimistic > > on the 5335's part. I think you should not use those sales-numbers, as they > > are > > there to give you a one-figure-of-merit hint, but they are not qualitative > > values. > > > > > >> That's 3 orders of magnitude better resolution. That brings up noise that > >> at > >> 9d/s is simply negligible. > >> > > > > I'd suspect something like 40 times better, not 1000 times better. > > The 5335 singel-shot resolution is 500 ps while the 5370 has 25 ps, a > > factor of > > 20. The front-ends is not that good on the 5335 thought, so let's add some > > noise there. > > > > I could make some tests if you like... > > > > > Actually the 5370 single shot resolution is 20ps, however the noise is a > little larger than that. Thanks for correcting that. My memory failed me there... > It can be much larger if the input signal slew rate at the trigger point > is much less than about 7.5V/us (input attenuation = 1X). > The performance also deteriorates when the input amplifiers are severely > overdriven. > Since the 5370 input amplifier noise bandwidth is 500MHz the wideband > noise seen by the 5370 inputs should also be low. Trigger jitter always adds, but single shot resolution limits the "digits per second" fairly well. > >> My two 5370s are rock stable if I only look at the 9 left-most digits. > >> > > > > Maybe you should trim your multiplier chain? > > > > > Aligning the various filters in the 10MHz to 200MHz multiplier chain can > make a considerable difference to the apparent noise. Indeed. Cheers, Magnus _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
