Just remove the TCXO the 10811 just plugs in,  you will need to add the heater oven indicator wiring and LED indicator which is usually over the power switch  The power supply includes the oven supply already

Content by Scott
Typos by Siri

"Just remove the TCXO the 10811 just plugs in"

Note that there are many different versions of the 10811. I am familiar
with at least two incompatible mechanical configurations: one is
connectorized and the other is not.

Didier KO4BB

On Thu, Nov 27, 2014 at 5:43 PM, Scott McGrath scmcgrath@gmail.com wrote:

Hi

In this case I suspect he’s referring to the version with the edge connector on it. That’s the one most instruments use rather than the connector only version or the “double oven” version. I believe that makes it a 10811A rather than a 10811B.

There are a multitude of details here:

https://www.febo.com/pages/hp10811/HP10811AB-Manual.pdf

There are indeed other versions that came out after the manual.

Bob

You are correct  I was referring to the 'instrument' version of the 10811A with the edge connector.

There are a lot of 10811A variants out there but the edge connector version was used in most HP instruments with an ovenized time base of that vintage.

It's worth buying dead option 1 instruments as they will have either a 10544 or 10811A as the time base mount point and electronic interface are standardized so upgrades are easy.

Content by Scott
Typos by Siri

Hi

That of course assumes that the OCXO is still in there. Most of the time it’s still there. I’ve seen a couple of sellers who (maybe) “part out” dead gear. It may have been done upstream of them, who knows.

Bob

On 27 November 2014 at 22:38, Dr. David Kirkby (Kirkby Microwave Ltd)
drkirkby@kirkbymicrowave.co.uk wrote:

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.

Dave

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@kirkbymicrowave.co.uk wrote:

On 27 November 2014 at 22:38, Dr. David Kirkby (Kirkby Microwave Ltd)

This got me thinking.

For anyone else owning a HP 5342A with a TCXO, it would be fairly trivial &
very  cheap to fit a low cost ($20 or so) OCXO on a bit of strip board and
it should improve the performance for very little money. The strip board
would just plug in the same socket as the HP TCXO or OCXO. A cheap unit
would not have the performance of a 10811A, but the price would be a lot
lower than a used 10811A.

Dave.

Adrian,
if you do not insist on a hp10811A, have a look at Gerrys site
http://gerrysweeney.com/update-diy-hpagilent-53131a-010-high-stability-timebase-option-pcbs-available/
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.
Götz

Am 29.11.2014 22:19, :