[time-nuts] 5370B arrived - any FAQ

phil fortime at bellsouth.net
Thu Jun 19 09:58:19 EDT 2008


I Didn't look at pulse bandwidth. 2.4ns compared to 10 ns
Other than that about the same unit.

----- Original Message ----- 
From: "phil" <fortime at bellsouth.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Thursday, June 19, 2008 9:48 AM
Subject: Re: [time-nuts] 5370B arrived - any FAQ


> 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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