[time-nuts] HP 5370B
bruce.griffiths at xtra.co.nz
Sat May 10 08:15:34 EDT 2008
Magnus Danielson wrote:
>> 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
>> 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.
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
Since the 5370 input amplifier noise bandwidth is 500MHz the wideband
noise seen by the 5370 inputs should also be low.
>> 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.
>> While it would be nice to have the same stability at 12d/s on the 5370 as we
>> get on the 5335 at 9d/s, that simply does not happen.
> I don't see how you could expect that. 10 digits stable should be possible, but
> again it is just a very very rought estimate of performance.
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