[time-nuts] Entry level systems HP 5345

Brooke Clarke brooke at pacific.net
Wed May 24 21:24:49 EDT 2006

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.

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.

Have Fun,

Brooke Clarke

John Day wrote:

>At 06:31 PM 5/24/2006, John Ackermann N8UR wrote:
>>Keith E. Brandt, M.D. said the following on 05/24/2006 06:06 PM:
>>>   What's a good entry-level time reference system? I'm doing this for
>>>   the fun/learning/hobby and can't dump $10k into it (without also
>>>   incurring the attendant lawyer's fee for the divorce settlement :-)
>>>   I think something along the lines of the TAPR TAC would be perfect if
>>>   they still made it. Are there other relatively low-cost GPS reference
>>>   systems out there?
>>Interesting question!
>>Assuming you mainly want to have a test-bed for learning and
>>experimentation, I'd say you want three things:  1) a local frequency
>>standard, 2) a frequency/time interval counter, and 3) a GPS or other
>>radio reference.
>>For the frequency standard, one of the surplus HP 10811A or 10544A oven
>>crystal oscillators ("OCXO") which can be had on eBay for $50 - $150
>>would be good, or one of the surplus Efratom Rubidium standards that go
>>for the $250 range -- each has its own advantages; the crystal will have
>>better short term stability and less phase noise, but the Rb will have
>>better long term stability and will need to be recalibrated far less often.
>You will often find that it is cheaper to buy a counter with the 
>high-stab oven option than to buy the oven separately.
>>For the frequency counter/time interval counter, I am very partial to
>>the HP 5334A or B.  They are quite cheap on eBay (usually less than $150
>>and have 2ns time interval resolution.  As a bonus, many of them have
>>the high-stability option (001) that includes an HP 10811A oscillator,
>>and if you find one with the "channel C" option you will be able to read
>>frequency to 1.3GHz.
>The 5335A is also sold from about $100 up and has the oven option as 
>opt010, 1.3GHz is opt030 and opt040 - expanded HPIB control is worth 
>having if you plan to remote the counter at all.
>A little heavier is the 5345A which can be equipped for operation all 
>the way to 40GHz or so at not a huge expense. It is one of my all 
>time favourites. It has 2ns resolution and counts direct to 500MHz. 
>They came as standard with the high stab oven, opt001 removes the 
>oven. Opt010 is very basic HPIB talk only, opt011 HPIB with remote 
>programming, opt012 is HPIB like 011 but has control of slope and 
>trigger level as well.
>You can pay from $80 or so for basic counter with HPIB. Just get the 
>seller to confirm it is not Opt 001! The 5345 is heavy, and a bit 
>noisier than the newer 5334A/B or 5335A. To my m ind if you are 
>interested in frequerncy measurement, this counter can give you 
>flexibility well beyond anything else that mere mortals can afford 
>when coupled with various plug-ins and convertor heads.
>73's, John (ex VK3ZJF)
>>Finally for the GPS.  We're in a state of flux right now because
>>Motorola sold their line of GPS receivers and the one everyone would
>>have recommended last year is no longer available.  Nonetheless, you may
>>be able to find an M12+T receiver which is the best unit they had
>>available, or the slightly older UT+.  You'll need an antenna, but you
>>don't necessarily need the TAC-2 -- all it really does is provide power
>>supply and I/O buffering.  You can do that on a piece of perfboard if
>>you want.
>>There are lots of other neat toys, but with those three you'll have a
>>good frequency standard and a way to calibrate it.
>>Hope this helps.
>>time-nuts mailing list
>>time-nuts at febo.com
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