[time-nuts] 5370B arrived - any FAQ

phil fortime at bellsouth.net
Thu Jun 19 09:48:50 EDT 2008

Why an 8082A, that's a 250MHz unit. Would not an 8015A 50MHz work. I think 
it's the same only with a lower bandwidth.

----- Original Message ----- 
From: "wje" <wje at quackers.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Thursday, June 19, 2008 9:01 AM
Subject: Re: [time-nuts] 5370B arrived - any FAQ

>   Why, you use your 8082A! I got one for a steal a couple of years ago on
>   EBay.
>   However, all you really need is a fast rise-time pulse generator that
>   has external triggering and a variable trigger delay, and can generate
>   a +1/-1 volt swing. The frequency the tests use aren't that critical,
>   anything 1Mhz or higher should work. The only semi-critical parameter
>   is the rise time; the faster it is, the less trigger uncertainty you'll
>   have. 1ns is good. :) Also, unless the delay time setting is rather
>   fine, it's extremely difficult to actually do the anti-coincidence
>   alignment.
>   What I'm missing is a spectrum analyzer, so I haven't done the
>   frequency multiplier alignment on either of my 5370s. Any tricks for
>   doing that without one?
> Bill Ezell
> ----------
> They said 'Windows or better'
> so I used Linux.
>   Chuck Harris wrote:
> wje wrote:
> Freq vs time interval - simplistic answer: when you're using
> time-gating, you're looking at more samples than in averaged one-period
> mode. For 10Mhz, a gate of 0.1 secs is 1 million periods. In period
> mode, you're averaging a maximum of 100,000 periods. Accuracy is
> proportional to the square root of the number of samples.
> Also, the trigger point jitter when in one-period mode affects every
> sample, but when in gate mode it only affects the first and last
> cycle.
> The 'specifications' section of the manual gives the formulas for
> determining both resolution and accuracy (which are NOT the same) for
> the various modes.
> I would suggest you go through the detailed alignment procedures even
> though the unit passes the operational checks. These units almost always
> have drifted out of alignment in the analog front-end unless you were
> lucky enough to get a freshly-calibrated one. You can usually
> significantly improve channel-to-channel trigger consistency and lower
> the jitter by doing so.
> What does one do where the tests call for an HP8082A pulse generator?
> The silly things are so rare that they are priced in the stratosphere!
> -Chuck Harris
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