[time-nuts] Frequency Counter Choice

[Bob kb8tq]

Hi

> On Oct 22, 2020, at 7:50 AM, Giorgio Barinetti <giorgio at barinetti.it> wrote:
> 
> Hi,
> 
> As a newbie in the field, I've collected, by chance, some frequency standards.
> 
> Now is the time to measure them, and see how they perform.
> 
> I've inherited a 5371, but something tells me that is not the right instrument - and maybe is even faulty.
> 
> So, I'm in the need to buy a counter to use togheter with TimeLab.
> 
> Choices are many, but I'll try to avoid the "older" machines lile 5370 or 5335. The 531xx series seems nice ( money apart )
> But again : which one between the 3 ? 53131, 53132 or 53181 ?

53181 = single channel 400 ps counter
53131 = dual channel 400 ps counter
53132 = dual channel 100 ps counter

5370 (when working) = dual channel 20 ps counter 

The gotcha is that none of them are good enough to properly measure 1 
second ADEV on a good ( but still could be cheap ) OCXO. A mixer based
setup is a cheap way to get things done, even with a 5335.

The 531xx counters all share a couple of issues:

1) The power supply was made by who knows who and their quality is not 
the best. Good news is that the power supply out of a (cheap) 53181 will 
swap over to revive an expensive 53132.

2) They have a fan, it plugs with dust. When that happens it gets hot inside
the cabinet. Things (like the power supply) die as a result.

3) They have a VFD display. It’s a nice one, but they do wear out. Replacing
them is problematic.

4) They have a fancy setup to add digits to a frequency measurement. It
can lead you astray. It also tends to go deaf right at 10 MHz. There are app
notes out there that explain the details. 

5) With *any* counter, a good external reference is the way to go for “Time Nut”
grade measurements. 

None of that is to say they are a bad counter, far from it. I have a number
of them and have been using them here and at work for decades. The 532xx
counters are the latest and greatest. They are on eBay, but not cheap. 

Bob



> 
> Can somebody shed some light, and maybe help even to found a baseline for us beginners ?
> 
> Regards,
> IZ2JGB
> Giorgio
> 
> My NTP servers: (ntpd on FreeBSD - PPS in via Serial)
> 
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> 
> Efratom Rb/Xc GPSDO https://www.ntppool.org/scores/95.255.136.126
> 
> 
> 
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