Hi Don,

On 01/09/2013 02:32 AM, dlewis6767 wrote:

Of the given set, the HP5370 will have much better single shot
resolution compared to the HP5371/5372. The later is better at recording
high rate events.

I have both HP5370 and HP5372 as they fill different purposes. I also
have counters of better performance than these.

Trouble is, with PPS signals you experience jitter such that a 1 ns
resolution of a HP5335 will suffice for most usages.

Cheers,
Magnus

Hi Magnus, ....good day.

Thanks for the thoughts, ...that was pretty much where I was headed.  I
think I will hold out a while for a 5370, ....watch eBay, see if a
reasonably priced unit pops up.

If anyone has one for sale for a nice price, please let me know.

-Don

From: "Magnus Danielson" magnus@rubidium.dyndns.org
Sent: Tuesday, January 08, 2013 7:42 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Interval Timer Recommendation

In the past there has been much discussion on this list regarding the
relative strengths and weaknesses of the 5370 (20ps resolution) and the
5371/5372 (150ps resolution) units.  There are other units that have
even better resolution, but they tend to be pricey and/or more specialized.

Moving down another step in resolution, the Racal-Dana 1991 and 1992 (1
ns resolution) counters also have their fans (like me), but they do have
problems with their front panel buttons (actually the switches under the
buttons).

Yes, the prices on ebay are becoming increasingly ridiculous.
Occasionally a seller will have an attack of sanity and post a
reasonable price.  You may also get lucky with a unit that is defective,
or advertised as such, but has either no fault or a repairable one.

More info on all of these topics is available by using Google with the
site:www.febo.com advanced search term.

Ed

On 1/8/2013 7:32 PM, dlewis6767 wrote:

Wasn't this the exact application the PicTic was developed for "So one
would not have to tie up an expensive counter for something like comparing
two standards."  It would in fact be perfect.  You'd need to build several
of them one for every two GPSes

Chris Albertson
Redondo Beach, California

Hi

There are a number of counters that are a lot better than what you have. There's also a limited amount of money in the universe. I'd suggest setting a rational budget and time frame. This is all used gear. You might get a perfect one that never ever breaks. More likely you will need to get a couple and swap things around. I'd plan on buying 3 or 4 with what ever the budget is. If you get lucky, you come in under budget.

Less fancy:

5334 - couple of ns resolution, nice and small, B is very different than the A so get one or the other
5335 - faster bigger heavier, one ns resolution.

both should be around $100 before shipping.

Very cool:

53131 500 ps resolution
53132 150 ps resolution

both have displays that can wear out. They are no longer supported by HP so you might find somebody dumping them. Hard to find for less than $800.

Big and heavy:

5371, 5372 same resolution as the 53132

They don't show up much. I've seen them for $200. You probably should expect to pay $400. Expect shipping to be non-trivial.

High end:

SR620
5370
53230a

All are in the 20 ps range. You do see 5370's for $200. More commonly you see them for quite a bit more. The 620's show up anywhere between $800 and $3000. The 53230a is brand new with a warranty from Agilent for about $3700.

That's just one set of parts. There are others. There are more issues than just price to consider. The 5371 is a big piece of gear. The 53xxx boxes are all small enough to carry around.

Lots of choices.

Bob

On Jan 8, 2013, at 9:50 PM, dlewis6767 dlewis6767@austin.rr.com wrote:

Thank you Bob, Ed, Magnus , ..and all.

Excellent reviews, ...detailed and clear.  I REALLY do appreciate it.

HP has turned out so much equipment over the years, it is often good to see
a comparison.  This was excellent.

I'll wait for a good deal, ....and don the road bid alongside many of you ,
I presume.  :-)

I may opt for one of the better units, ...as this disease progresses.

-Don

From: "Bob Camp" lists@rtty.us
Sent: Wednesday, January 09, 2013 6:43 AM
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Subject: Re: [time-nuts] Interval Timer Recommendation

Hi

Keep in mind that the "good" prices are generally for gear that is in the
"don't know if it works at all" category. The prices go up quickly for stuff
that has had even basic checks run on it.
It's rare to find any of this stuff with a believable iron clad guarantee /
certification that it runs 100% to original specs. I've seen a lot of gear
with cal stickers on it that doesn't do this or that correctly...

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of dlewis6767
Sent: Wednesday, January 09, 2013 8:07 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Interval Timer Recommendation

Thank you Bob, Ed, Magnus , ..and all.

Excellent reviews, ...detailed and clear.  I REALLY do appreciate it.

HP has turned out so much equipment over the years, it is often good to see
a comparison.  This was excellent.

I'll wait for a good deal, ....and don the road bid alongside many of you ,
I presume.  :-)

I may opt for one of the better units, ...as this disease progresses.

-Don

From: "Bob Camp" lists@rtty.us
Sent: Wednesday, January 09, 2013 6:43 AM
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Subject: Re: [time-nuts] Interval Timer Recommendation

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

On 01/09/2013 05:39 AM, Ed Palmer wrote:

The 5371/5372 has a 200 ps resolution. They where designed to allow
extension to 100 ps resolution. The FLASH-interpolators have 200 ps
steps, sufficiently good trigger such that you get 150 ps resolution
performance on the white-noise limit.

Cheers,
Magnus

and don't forget the PM6681 (50pS)

On Wed, Jan 9, 2013 at 7:29 PM, Magnus Danielson <magnus@rubidium.dyndns.org

On 1/9/2013 12:48 PM, Azelio Boriani wrote:

The PM6681 was sold by Fluke/Philips. The same counter is also
occasionally seen as the Pendulum CNT-81. Additional good features:
small, light, and quiet.

On 01/10/2013 12:02 AM, Rex wrote:

A bit more history then.

Philips had a sub-sidary called Philips Industrier Järfälla, located
just outside Stockholm. They made amongst other things OCXOs and
counters, but a numerous of other measuring gadgets. As Philips merged
with Fluke for instruments, the Philips Industrier measurments gear also
re-occured in their Fluke variant for the US market. They kept their
PMxxxx model numbers. As Philips was retracting from the market, they
sold of the T&F reminder of Philips Industrier and that was named
Pendulum, which kept the connection with Fluke. This meant that the new
counters coming out also came out in their Fluke variants. However,
pendulum decided to strike out the PM66 prefix (for counters) for their
Pendulum branded gear and had different prefixes such as
CNT-80/81/85/90/90XL/91, GPS-12/88/89 and WM-10/11. Pendulum was sold
off to SpectraCom, and it was run as a separate business for some time,
but eventually the old company was dismantled and Pendulum remains as a
brand within SpectraCom. The product range exists, except for the CNT-8x
series which died off then the last of the custom counter chips ran out,
besides what was kept for service of course. The CNT-9x series uses a
FPGA as counter core. Today only a few of the original staff remains
with SpectraCom. The CNT-90 has also appeared in Tektronix format.

I had some exchange with them as they where local to me.

Cheers,
Magnus

On Wed, 09 Jan 2013 21:48:00 +0100, Azelio Boriani wrote:

I have a PM6680 (250 or 300pS) i think , but it was within my budget.

I just read the Service manual , and noticed that both the PM6680 & the
6681 has a battery inside that holds the settings.
The manual states that loosing the settings on a 6680 is no big problem ,
but on the 6681 you loose the interpolator calibtation. And it sounds
like that's not a good thing.
I didn't know you had to watch out for Battery on a PM6680/81.

CFO - Tnut-Beginner
Denmark

Yes, the battery on the PM6681 is a real problem, unless you have the
unobtainable calibration program. The program uses the GPIB to perform the
calibration: I have tried to figure out the GPIB commands involved in the
calibration process by looking at the firmware dump... the commands are
clear text. I wasn't able to find anything.

On Thu, Jan 10, 2013 at 6:37 PM, cfo xnews3@luna.dyndns.dk wrote:

On 2013-01-10 23:14, Azelio Boriani wrote:

I did read about the battery before, but did not know how severe the
problem was. Thanks for the heads up! Does the PM6685 end up in the same
category as 80 or 81 in this respect?

I want to send a thank you to everyone participating on this thread, I'm
sure I'm not alone looking for a (or another) time-nut friendly TIC.
Finding one that's, "good enough" electrially (all parameters up to
desired specs), user friendly, not humongous and affordable was harder
than I initially thought it would be.

So far I've seen the Racal-Dana 1991/1992, horde of HP/Agilents and
Philips/Fluke/Pendulum CNT-/PM66* mentioned here. Keeping a searching
eye out for one that isn't 19" and doesn't weight too much given the
frequency of which I will lug it around. Or failing that cheap enough
to double up.:)

To me this so far means I'm primairly looking for Racal-Dana's as a
cheap option or possibly PM66's if I can find them (much rarer here, but
I like that they're made in Sweden!:). Are there any HP's I should keep
a look out for, if I'm aiming for at least 1 ns resolution? Bob's list
(a special thanks to you for the comprehensive list) left me with only
finding either very expensive or very big ones in Europe.

Any recommendations for where to look for timing equipment (TICs
specifically but I guess it will be the same answer in general) in
Europe besides the one all so familiar auction site? (Not that I have
anything against ebay, just checking if there are any secondary sources.)

// jwalck

HI

One thing missing from the list was the HP 53181. It's useless as a timing device and thus didn't get listed. If you are after frequency only, they occasionally show up for quite a bit less than the 53131's. As a frequency counter, they have the same performance as a '131. All of the 53131, 132, 181, and 230's are small enough to lug around.

Bob

On Jan 10, 2013, at 7:03 PM, Jonatan Walck jwalck@netnod.se wrote:

Would loss of interpolation calibration have much impact on its use as a TIC?

On 01/11/2013 03:51 PM, Chris Howard wrote:

Yes, as that is what gives you the precision. I don't recall how bad it
will get, but I ended up having the PM6681 calibrated.

Cheers,
Magnus

The PM6685 is a frequency counter, not a TIC, so it shouldn't suffer from
the battery problem.

On Fri, Jan 11, 2013 at 7:33 PM, Magnus Danielson <
magnus@rubidium.dyndns.org> wrote:

On 01/11/2013 09:09 PM, Azelio Boriani wrote:

It's single shot resolution would still be from the interpolator, even
if you measure on the same signal.

Cheers,
Magnus

OK, but I wasn't able to find a single shot resolution specification in its
datasheet. Looking at the formulas to determine the accuracy, it looks like
the minimum resolution is 250pS... anyway, by reading the user and service
manual I found out that the PM6685 has an EEPROM memory and no battery is
needed.

On Fri, Jan 11, 2013 at 10:15 PM, Magnus Danielson <
magnus@rubidium.dyndns.org> wrote:

On 01/12/2013 01:37 PM, Azelio Boriani wrote:

At 250 ps you use interpolators. The typical coarse counter would be 100
MHz and that means 10 ns in raw resolution, but you would then use an
interpolator to get higher resolution. By getting a start and stop
measure, roughly tau time inbetween each other you get
f = (t_stop - t_start)/tau
assuming t_start and t_stop trigger from the same source.

For frequency measures you can overcome the single-shot resolution by
using multiple start and stop locations and process the estimates.

BTW, some counters use quite different approaches for triggering and
routing their TI measures and their frequency measures, to such degree
that frequency trimming requires separate calibration. SR620 is one such
example. Typically would the calibration error cause a static time error
between start and stop, and scaling with tau is a good way to track it.
Measuring it's own time-base is a good way to measure this calibration
error and trim it out.

Cheers,
Magnus

On 1/12/2013 7:40 AM, Magnus Danielson wrote:

This may not be of interest, and if so, I'll drop it.
But I was thinking that if they go to some kind of
fallback interpolation the time interval measurements
at a more-or-less fixed frequency might still be
pretty good.

(I think along these lines because maybe someday
a battery-bad unit might show up which is not so good
at umpty-GHz measurements but still OK for TIC)

If it had a systematic error at 10MHz it seems
like maybe that would just fall out in the wash. (?)

Chris

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On 2013-01-11 02:48, Bob Camp wrote:

I'll find uses for a full TIC rather than just a fequency counter, but
I absorb all this knowledge happily either way and it's good to have
that here as a reference.

I initially found the 53131A and everything above it to steep for my
first home lab TIC but you are right about the size, they are quite
small. (Having access to 53131's through work.)

As great luck would have it though, I found a second hand Pendulum
CNT-90 and I got a too good deal to hold back my trigger finger.
Picked it up yesterday! Made no measurements past "does it start up
and can it detect any frequency?" yet but will put it to good use soon.

I wouldn't have know what to look for and find this TIC without this
list. A big thanks to all time-nuts once again!

// jwalck
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A bit late in the thread but I don't see the HP E1740A

-pete

On 1/14/13, Jonatan Walck jwalck@netnod.se wrote:

Hi

I'm not quite sure if the 1740 is a counter or not. I have a few of them
sitting here, but they are a bear to do anything useful with. They make the
5371 look like a portable instrument.

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Pete Lancashire
Sent: Tuesday, January 15, 2013 9:35 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Interval Timer Recommendation

A bit late in the thread but I don't see the HP E1740A

-pete

On 1/14/13, Jonatan Walck jwalck@netnod.se wrote:

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