[time-nuts] Entry level systems HP 5345

John Day johnday at wordsnimages.com
Thu May 25 00:01:10 EDT 2006

At 09:24 PM 5/24/2006, Brooke Clarke wrote:
>Hi John:
>I'm using the HP 5345A opt 11 now and really like it.  When in the Time
>Interval mode (cesium s/n 1227 1 MHz on start and cesium s/n 1013 1 MHz
>on stop) you can turn the Gate Time knob up from  "MIN" to say "1 SEC".
>What this does is to accumulate the gate times for as many receptive
>measurements as it takes to get to a total of 1 second, so the number of
>measurements depends on the actual TI being measured.  For example with
>1 SEC gate time and a TI of about 574 ns it takes about 3 seconds of
>clock time per measurement.  The display is like 574.419,441 nano
>seconds.  That's 574 nano seconds and 419 pico seconds and 441 femto
>seconds.  If you set the gate time longer you get more digits.  So at 10
>SEC you get 0.1 femto seconds resolution after a 30 second wait.  Simply
>It counts to 500 MHz without any plugins unlike the HP 5245 that needs a
>plugin to get to 500 MHz.  But a drawback to the early models is that
>the air filter is buried behind the FRONT panel and needs servicing
>something like twice a year.  This required taking the counter apart.
>In later versions they removed the air filter.
>Although I can read HP-IB data in talk only mode, I haven't figured out
>the secret of two way communication.

Hmm, I am not sure if I have any code left lying around for the 
thing. Possibly in RMB. I loved the 5345A, I lashed out as a young 
man and bought my first one for some horrendous amount of money in 
1972 when they first came out. I remember the HP salesman coming to 
see me and he left me his demo unit. It was so pleased with it for 
what I was doing that I insisted he leave it until he could get me 
one for myself! Later I had occasion to purchase more of them and 
when we pensioned them of in favour of newer devices, I picked one of 
the newer ones with a 5355A plugin and a 5356B head for myself.

In a fit of inexplicable madness and incipient senility I let the 
thing go last year for way too little money.

>But the SR620 is still hands down my favorite TI counter. 16 digits with
>a fixed weight on the positions is a really good layout.

I would love to get hold of an SR620, I have never used one but the 
spec and manual certainly reads well. Now as a "tinkerer" I can't 
afford to lash out the dollars I once could. I have a Tektronix 
DC5010 - 3.25ns resolution as I recall. But to be honest I don't like 
it. It does the job I need it for right now, but as soon as I find a 
5370B or an SR620 I can afford, it will go.

>Have Fun,
>Brooke Clarke
Oh I am always having fun of some sort!

John Day

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