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HP 5335A Timer / Counter - Anything i should know?

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tkamiya:
A new HP5335A with OCXO and 1.3GHz option just arrived.  It is in beautiful shape and seems to work as it should.  I will be keeping it plugged in for a day or two and see where it settles.

My goal is to have two of each so I can do A/B testing easier. 

FriedLogic:

--- Quote from: tkamiya on February 23, 2019, 01:53:28 pm ---
Maybe I'll make two identical setup and do a controlled comparison study.  I have a stack of Rubidium modules.  It should be quite interesting.

--- End quote ---

That's the way to go. Once you have a basic test rig set up you can build on that, then decide what performance you want to aim for and how to measure it. Once you get it up and running you'll get a better idea of where to go next.

If you're trying to squeeze the best performance from a rubidium, temperature is normally the most important thing, followed a fair bit after by air pressure - but that's more a discussion for one of your rubidium threads rather than this one.

tkamiya:
Dr. Frank,

As I mentioned earlier, I acquired another HP5335A and this time, it comes with factory oven crystal, 10811-6011.  After overnight warm up with case closed, I opened it this morning and immediately touched top and side of the module. 

They are only very very slightly warm in certain spots.  Other parts are absolutely same temp as air around it.  This unit still has a factory fan.  (a turbo jet!)

So it is confirmed that IS the expected behavior.  HP has designed a duct system that keeps the Xtal cool.  I am not going to keep the case open to validate how hot it will get.  I think it's unnecessary.

I thought I'd report in and leave this, in case someone else wonders in future.

tkamiya:
Fried Logic....  what an interesting handle!

To do an A/B comparison, I'd like to keep everything else the same except the element I'm testing.  I know each counter has certain characteristics since they are so heavily software involved.  I've learned they do quite a bit of massaging and post processing before the data gets on display panel. 

Besides....  this unit was very inexpensive on eBay.  I couldn't refuse....

LazyJack:

--- Quote from: Dr. Frank on May 26, 2014, 08:56:52 pm ---Yes sorry, I'm a bit late.
I had to study all the change history in manual 05335-90044, up to Serial Prefix 3154.

V1.1 had been introduced in June 1984, for all instrument with 2424A06001 and above.

V1.1  has one decimal point in the HP-IB string, as shown with my instrument.
V1.0 shows no decimal point in the GP IB string at all.

I already have the newer prescaler  in the C-channel (05335-60034), which divides by 64.
The old prescaler (05335-60009) divided by 20 only, therefore the firmware has to match.

It's not clear, if there exists an intermediate firmware which corrects all the bugs of V1.0, but is made for the old prescaler, i.e. multiplies the result by 20 instead of 64.

The difference may be inside the EPROM A4U22, as 05335-80012 (as in my unit) refers to the new /64  prescaler, and 05335-80006 refers to the old /20 prescaler.
That's change 7 in this manual, and affects prefix 2820, exactly my counter, and also for retrofitting the newer C-channel option 030.


Obviously, I have an intermediate A4 version, 2 EPROMs - but V1.1 and the newer prescaler. Perhaps my instrument had been updated, or the C - Input had been replaced.

I could not find a comprehensive table, which EPROM code refers to which firmware version, and/or to which prescaler.
Frank

--- End quote ---

Sorry to resurrect this thread, but I found this table. It is in the latest service manual (05335-90444, recently uploaded to KO4BB). It's on top of page 6-9 .

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