What test instrument is BNC jumper the from?

[graybeard]

This BNC jumper came with many RF adapters & terminations from disassembled test racks.  It looks like it was part a piece of test gear.
The BNC centers are exactly 1.8" apart.
A part number on on of the BNC connector is 28AU100-1
The date code is 4991 which I assume means the 49th week of 1991.
Do you have any idea what this is from?

Thank you,
Chris

[MarkL]

Most commonly, these fit the REF OUT to REF IN BNCs on the back of HP/Agilent 859x spectrum analyzers.  Their part number is 1250-1499.

People remove these from equipment and sell them individually, which is irritating when buying the equipment.  The all metal ones, like you have, sell for ridiculous prices.

The complete list of equipment from Keysight Find-A-Part that use it:

11758V
16096A
84100EM
84110EM
8542E
85462A
8546A
8590L
8591E
8592L
8593E
8594E
8594EM
8595E
8596E
8596EM
8642A
8924C
8924E
89410U-AY5
89431A
89441A
89441U-AYC
89441V
E4902B

[floobydust]

28AU100-1 used in HP3588A Spectrum Analyzer (HP 1250-1499) COAX BNC(M) to COAX BNC(M)
https://4gte.com/products/hp-agilent-1250-1499-adapter-coaxial-male-bnc-male-bnc/

[coppercone2]

thats a nice connector, very stable. The newer ones I think are more modular with sliding contacts so you can adjust their spacing but IMO this one is nicer, its just really specific