[time-nuts] Upgrade an HP 5342A microwave frequency counter to have an oven oscillator.
artgodwin at gmail.com
Sun Nov 30 16:43:16 EST 2014
I've seen Gerry's board and might well fit one to another counter.
However, this already has a suitable board - in fact, it appears it is
an oven, not a tcxo. Presumably just not as good an oven.
The point is, it looks ready to receive a 10811A. In fact, consulting
the assembly-level service guide does seem to confirm that it uses an
Isotech oven for medium stability or one of two 10811 variants for
high and ultrahigh stability.
Since the 10811A I have is an older model, neither 10811-60160 or
10811-60260, is it likely I'll get any improvment over the Isotech
Photos of the board :
On Sun, Nov 30, 2014 at 4:38 PM, Bob Camp <kb8tq at n1k.org> wrote:
> If you *need* portability, an internal oscillator is a good thing. If you want to fire something up fast, an OCXO is not a good choice. That's a bit of a problem.
> A few real choices:
> 1) Get something like the LTE that locks up to GPS and runs right away. When portable, bring along a small GPS antenna.
> 2) Run a TCXO in the counter while portable and an external reference on the bench.
> 3) Power up the counter with internal OCXO the night before any "portable" measurements.
> There really aren't a lot of other options unless you head off into the portable atomic clocks.
>> On Nov 30, 2014, at 11:08 AM, Götz Romahn <goetz at g-romahn.de> wrote:
>> if you do not insist on a hp10811A, have a look at Gerrys site
>> You can buy an assembled option 10 compatible OCXO modul for less than 100 GBP.
>> I built DIY one with a PCB from Gerry using my Morion MV89 OCXO and it is working fine. Fully compatible with hp53131 calibration procedure.
>> Am 29.11.2014 22:19, :
>>> Is the upgrade similarly easy on a 53131A ?
>>> I realise that it needs to have an additional controller pcb but I
>>> have one of these counters fitted with option 001. The pcb holding the
>>> oscillator has an edge connector that looks suitable for a 10811A, and
>>> I have one to hand as well as a couple of compatible oscillators.
>>> I think I would need to remove the existing TCXO module - I haven't
>>> investigated too carefully yet but I think it's soldered in, and
>>> obstructs the mounting of the 10811A.
>>> On Sat, Nov 29, 2014 at 5:20 PM, Dr. David Kirkby (Kirkby Microwave
>>> Ltd) <drkirkby at kirkbymicrowave.co.uk> wrote:
>>>> On 27 November 2014 at 22:38, Dr. David Kirkby (Kirkby Microwave Ltd)
>>>> <drkirkby at kirkbymicrowave.co.uk> wrote:
>>>>> The HP 5342A has an optional oven oscillator. I just bought one of
>>>>> those counters, but mine has a TCXO and is about 50 kHz off at 10 GHz.
>>>>> I'm sure I can trim it closer than that, but if possible I'd like to
>>>>> stick an oven oscillator in it. Does anyone know what is involved? I
>>>>> have at least one 10811A oscillator here that I could stick inside,
>>>>> but does it need any more, or just the oscillator?
>>>>> Someone said the oscillator should be an 10544-60011, but a 10811A is
>>>>> backwards compatible.
>>>> It was very easy to fit the 10811A oven (HP 10811-60111) and get the
>>>> oven working, although the oven is not powered when the counter is not
>>>> switched on, even if there is power at the AC mains input. I can live
>>>> with that. In fact, I prefer it to be honest.
>>>> The procedure was
>>>> 1) Remove top and bottom covers, which means the two front feet, plus
>>>> 4 rear feet/protectors need to be removed.
>>>> 2) Undo one screw at the top that held a board with a TCXO on it. The
>>>> board plugs into a 15-pin edge connector.
>>>> 3) Pull out the board (HP P/N 05341-60047) with the TCXO. The TCXO on
>>>> the board is a marked DALE, TCXO-22-1, 0960-0394, 10.0MHz, SET 1.0Hz.
>>>> (normally I would put a space between a number and the units, but I've
>>>> written what is actually on the TCXO).
>>>> 4) Attempt to insert the 10811A oscillator. This failed, as there were
>>>> some wires around the optional board for GPIB which were restricting
>>>> the space too much. So I had to cut a wire tie, and move the wires out
>>>> the way.
>>>> 5) Fitted 10811A at the top.
>>>> 6) Invert the counter, and screw in the two screws which secure the
>>>> 10811A to the chassis. For this I needed to temporarily move a ribbon
>>>> cable, as the screw was below it.
>>>> 7) Powered it up, and it worked. It shows "OVN" in the right of the
>>>> LED display. Once that went out, it still took a minute or two for the
>>>> readings to become pretty stable, although no doubt it will take
>>>> months to become as good as it will get.
>>>> I've not adjusted it yet, as I don't have any accurate frequency
>>>> reference. But whilst the actual frequency indicated on the counter is
>>>> different from what my signal generators are supposed to be producing,
>>>> the last few digits (100, 10 and 1 Hz), are not all jumping around
>>>> when seeing 10 GHz.
>>>> The frequency indicated on the counter when connected to two different
>>>> signal generators, which both have ovens of unknown type, are:
>>>> 1) HP 83623A 20 GHz sweeper set to 10.0 GHz, fed into high frequency
>>>> input of the frequency counter.
>>>> HP 5342A counter indicates 10,000,000,690 Hz (relative difference = +6.9 10^-8)
>>>> 2) HP 8656A set to 100 MHz,
>>>> HP 5342A counter indicates 99,999,987 Hz (relative difference = -1.3 x 10^-7)
>>>> With the old TCXO in the frequency counter, the indicated frequency of
>>>> the 10 GHz signal was about 48 kHz off, but it moved around a KHz or
>>>> so. In contrast, now the oven is installed, the reading is a *lot*
>>>> more stable, with it shifted about 15 Hz.
>>>> I don't currently know the absolute accurate any of the references in
>>>> the test equipment are, but certainly the readings are a lot more
>>>> stable after fitting the oven.
>>>> I will need to get a GPSDO before adjusting any, but if nothing else,
>>>> the short term stability of the oven is clearly superior to the TCXO.
>>>> Long term should be too, but I can't determine that from what I have.
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