What were these 125 Ohm Tektronix attenuators for?

[graybeard]

I picked up these two 125 Ohm Tektronix attenuators with many other 50 Ohm attenuators at the W6TRW swap meet last Saturday.  They initially appear to have GR874 connectors, but the center contact is not compatible with a standard GR874 connector.  It will "mate" with a standard GR874, but the center contacts do not connect.

The first part is a Tektronix 017-071 2X (6dB) 125Ω attenuator
The second is a Tektronix 017-050 10X (20dB) 125Ω attenuator

Do you have any idea what these were for?

There are pictures of both below.

[graybeard]

I also picked up this Tektronix 067-0511-00 variable attenuator which has a 100Ω linear potentiometer and standard GR874 connectors.

[factory]

The 125ohm GR attenuator are used for the Tek 519.
https://w140.com/tekwiki/wiki/519

David

[graybeard]

The 125ohm GR attenuator are used for the Tek 519.
https://w140.com/tekwiki/wiki/519

David

They are listed as optional accessories for the 519 on page 66 of the 1968 catalog.