HP BNC connector - UK Vintage Radio Repair and Restoration Discussion Forum

Alan Bain · 20th Mar 2024, 12:31 am

I'm looking for an HP 1250-0870 BNC panel mounting socket. It mounts in a D shaped cutout in the panel and is intended for direct attachment of a coax.

(An elephant seems to have sat on one on an HP frequency source and rendered it elliptical. I thought I had some suitable replacements, but they mount in a much smaller hole)

Various sources exist - but I don't like the sound of ones that suggest they were pulled from nice pieces of HP test equipment!

Alan

Julesomega · 20th Mar 2024, 12:41 am

That looks like a thin coax cable like RG188 or RG174, in which case I have two possible candidates. Let me know the critical mounting dimensions.

Alan Bain · 20th Mar 2024, 11:45 am

The mounting hole cutout looks like this. Dimensions are marked but since handwriting on a mouse pad can be hard to read it is essentially a truncated 12.73mm diameter hole with distance from flat to edge at 11.90mm (I am sure this was originally in inches!)

Julesomega · 20th Mar 2024, 1:55 pm

Your internal dimensions are 0.1mm larger than the connector external dim's! I'll pop one in the post if you PM or email me your address. The screen connection has to be crimped, so leave that til last and crimp lightly with pincers or large pliers. The centre pin is soldered, you can see the capillary feed hole on the similar RG58 type on uk.rs-online.com
Unfortunately their datasheet omits any assembly instructions so you will have to work out the cutting lengths by careful experiment.

Radio Wrangler · 20th Mar 2024, 2:21 pm

Actually, it looks just like the one I'm holding in my hand

1250-0870 50 Ohm short-thread BNC on one end, about 2 ft thin 50 Ohm coax and a 50 Ohm SMB on t'other end. Yup, it's actually marked 1250-0870 on the connector

And it even has the tiny EMC toroid on it.

It was something I kept as a spare when I put the gated sweep measurement hardware in my 859x prototype analyser. So, completely surplus to requirements.

David

Alan Bain · 23rd Mar 2024, 7:47 pm

Thanks for a couple of very kind offers of assistance above. I took up David's offer and the socket with lead arrived today. As might be expected since it is the identical part number to the damaged one, it fits perfectly.

Moderators, this thread can now be closed.

Radio Wrangler · 23rd Mar 2024, 11:06 pm

All's well that ends well, and Julian's pristine new BNC remains should he need it for something afresh.

David

20th Mar 2024, 12:31 am	#1
Alan Bain Pentode Join Date: Jan 2012 Location: Heswall, Merseyside, UK Posts: 177	HP BNC connector I'm looking for an HP 1250-0870 BNC panel mounting socket. It mounts in a D shaped cutout in the panel and is intended for direct attachment of a coax. (An elephant seems to have sat on one on an HP frequency source and rendered it elliptical. I thought I had some suitable replacements, but they mount in a much smaller hole) Various sources exist - but I don't like the sound of ones that suggest they were pulled from nice pieces of HP test equipment! Alan Attached Thumbnails

20th Mar 2024, 12:41 am	#2
Julesomega Nonode Join Date: Dec 2012 Location: Stockport, Greater Manchester, UK. Posts: 2,122	Re: HP BNC connector That looks like a thin coax cable like RG188 or RG174, in which case I have two possible candidates. Let me know the critical mounting dimensions. Attached Thumbnails __________________ - Julian It's good here

20th Mar 2024, 11:45 am	#3
Alan Bain Pentode Join Date: Jan 2012 Location: Heswall, Merseyside, UK Posts: 177	Re: HP BNC connector The mounting hole cutout looks like this. Dimensions are marked but since handwriting on a mouse pad can be hard to read it is essentially a truncated 12.73mm diameter hole with distance from flat to edge at 11.90mm (I am sure this was originally in inches!) Attached Thumbnails

20th Mar 2024, 1:55 pm	#4
Julesomega Nonode Join Date: Dec 2012 Location: Stockport, Greater Manchester, UK. Posts: 2,122	Re: HP BNC connector Your internal dimensions are 0.1mm larger than the connector external dim's! I'll pop one in the post if you PM or email me your address. The screen connection has to be crimped, so leave that til last and crimp lightly with pincers or large pliers. The centre pin is soldered, you can see the capillary feed hole on the similar RG58 type on uk.rs-online.com Unfortunately their datasheet omits any assembly instructions so you will have to work out the cutting lengths by careful experiment. __________________ - Julian It's good here

20th Mar 2024, 2:21 pm	#5
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,915	Re: HP BNC connector Actually, it looks just like the one I'm holding in my hand 1250-0870 50 Ohm short-thread BNC on one end, about 2 ft thin 50 Ohm coax and a 50 Ohm SMB on t'other end. Yup, it's actually marked 1250-0870 on the connector And it even has the tiny EMC toroid on it. It was something I kept as a spare when I put the gated sweep measurement hardware in my 859x prototype analyser. So, completely surplus to requirements. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

23rd Mar 2024, 7:47 pm	#6
Alan Bain Pentode Join Date: Jan 2012 Location: Heswall, Merseyside, UK Posts: 177	Re: HP BNC connector Thanks for a couple of very kind offers of assistance above. I took up David's offer and the socket with lead arrived today. As might be expected since it is the identical part number to the damaged one, it fits perfectly. Moderators, this thread can now be closed. Attached Thumbnails

23rd Mar 2024, 11:06 pm	#7
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,915	Re: HP BNC connector All's well that ends well, and Julian's pristine new BNC remains should he need it for something afresh. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done