HP 5386A frequency counter teardown

[remageFrs]

Hi!

First post here, so I thought it'd be a good idea to take some inside photos of an HP 5386A frequency counter I scored recently on eBay.
Also, I'm curious if anyone here has a similar counter with the "Option 004" OCXO timebase?

Higher resolution images are here: HP 5386A

Most of the ICs/caps have a late-'87 datecode, the TCXO has '8802' stamped on its side (but I'm not 100% sure that's a datecode), so I think it's an early '88 unit. Despite the age, the whole instrument looks really nice and clean.

I didn't have the confidence to open up the RF shield on the 3 GHz frontend, sorry... :)


Edit: Found the service manual on Keysight's homepage.
It mentions on page 2-4 that the standard oscillator can be replaced by the "Option 004"  OCXO. The HP number is 0960-0636, I couldn't find any further info about it. Does anyone have an idea if a modern ovenized oscillator can be installed there?

[deepskyridge]

I have one just like it except mine has the OPT-004 installed. Nice counter, mine works fine.

Gary

[picburner]

Nice instruments.
A guy in Poland has made an option 004 clone and sell it on ebay.

[remageFrs]

Found a NOS oven oscillator for the counter!

[corn11]

Found a NOS oven oscillator for the counter!

I have a 5385a on which I also want to install the option.
May I ask where you've managed to get the original OCXO ?
I've wrote some obsolete part suppliers but none of them has responded so far 

[corn11]

I think I've found the OEM of the OCXO: Isotemp Research Inc. .
They (presumably) sell the matching OCXO on eBay:

eBay auction: #171831243622

The given datasheet values correspond to the ones in the datasheet of the 5384A/85A/86A also the pinout and the shape, which aren't really common match.
It would be a really strange coincidence if this isn't the OEM part
I've recently ordered one and it should arrive this week.

[calin]

I have one too, no OCXO .. got it for 20$  .. With the spare money I got an UBLOX and a Morion OCXO and a couple of chips and I am almost done getting a half a$$, good enough for my needs GPSDO.


One thing that wold be a nice hack will be to add a backlight to the lcd.

[mmagin]

I have the 1 GHz version of this (without OCXO) and I previously had the 225 MHz version (with OCXO).  Nice little counters, though in both situations I used the 10MHz reference from my GPSDO instead.  Interesting that HP put a third party OCXO in these instead of the 10811 -- presumably it was a lot cheaper.

[corn11]

Building a GPSDO is also on my list. I've already bought a Navman-GPS-module and a Trimble OCXO but had no time to get the thing together.
So for now hopefully the OCXO option will do the business

yeah, a backlight hack would be really nice indeed I belief someone on the forum has already done this with a 3478A DMM.

[Miti]

yeah, a backlight hack would be really nice indeed I belief someone on the forum has already done this with a 3478A DMM.

https://www.eevblog.com/forum/testgear/hp3478a-backlight-my-version/msg1507039/#msg1507039

[0culus]

Really nice and clean too! Good catch! 

I have a 5335A with the OXCO option (and I think pretty much every other option as well; even the DC voltmeter option) that sits on top of my 5350B microwave counter, and provides the timebase for it. I recently also replaced my shitty Chinese DDS with a 3325B from the same seller I got the counters from, which also has an OCXO, but it doesn't have an internal connection to it, so I have a jumper.

[Jwalling]

Seeing as how this is a teardown thread, here's some pictures of the 3GHz prescaler.

[rhb]

Curiously, all my HP gear has the OXCO option except my Keysight 33622A.  But I plan to connect everything to a GPSDO, so I don't think it matters much.  Even without the OXCO the 33622A is very stable.  But I haven't put together a test and verification plan for my bench yet.

[Radiorandy]

I've been trying to find the guy in Poland that has the Option 4 clone OXCO. Doesn't show up on Ebay. Anyone have a link or contact info?
Thanks

Randy

[wkb]

Seeing as how this is a teardown thread, here's some pictures of the 3GHz prescaler.

Page 63 shows a picture of one of the GaAs chips used on the hybrid.

http://roryvantuyl.com/PDFs/The%20Early%20Days%20of%20GaAs%20ICs.pdf

Wilko