[time-nuts] HP 5328A Divider / Timebase Output performance

[Magnus Danielson]

John Miles wrote:
>> I would tend to say that the divider is pretty lousy for short
>> term, but it is all fine for longer runs, right?
>>
>> Is this what I should expect from a TTL/ECL divider chain
>> designed in the '70s-'80s? How would this compare to a modern
>> divider chain, like the PIC divider or David Partridge's divider board?
> 
> The 5370 residual plot I mentioned in the other message was taken under
> similar conditions as you describe, but with a TADD-2 divider, and is almost
> 100x better.  IMHO the 5328A solution doesn't look like a good one, since
> any inexpensive digital divider should be able to beat it.
> 
> It's true that factors like trigger levels and attenuator settings matter,
> but this will be observed at the tens-of-picoseconds level in my experience,
> not at 1ns+ timescales.  Triggering on the correct edge is likely to be more
> important.  Try it both ways and see if you notice a difference.

OK, so I tried this myself. A sloppy setup but never the less... The 
CNT-90 time-base output via a T-connection on B-channel and then over to 
the A input of the HP 5328, selected START A and then the T.B. OUT over 
to CNT-90 channel A. At 100 kHz setting on the HP 5328, the TI A->B 
measurement on CNT-90 shows some jitter, but RMS jitter is below 400 ps 
at least and ADEV readings somewhat below that.

A quick check for various settings doesn't show significantly 
differences. The period-plot showed sine-like variations, so maybe some 
50 Hz aliasing with the result.

Anyway, it doesn't look like Berts measurement. Then again, I did not do 
PPS output.

Need to do some proper setup. This was on the level of running down the 
lab for a quick testie. I knew that 5328 would come in handy as 
reference one day. It just did.

Cheers,
Magnus