Frequency Comparator Set AN/USM-144 is a precision frequency measuring device used with electronic counters to provide measurements of frequencies from 10 MHz to 12.4 GHz.

The USM-144 manual is here -

https://www.navy-radio.com/manuals/usm114-manual-6107.pdf

Reply directly to Asa - I know nothing more -

Feel free to forward to any who might be interested.

Nick K4NYW

---------- Forwarded message ---------
From: ASA GAWTHROP <argawthrop@msn.com>
Date: Wed, Nov 9, 2022 at 11:15 PM
Subject: Test Equip page
To: <nick@navy-radio.com>

Nick,
First, let me say that I have enjoyed looking at your equipment collection.

I am a retired EE and am trying to "dispose" of some of my old equipment.

I have an AN/USM-144 Frequency Comparator Set that I acquired from a
local ham in the 1970's. I had used it up into the early 1980s. I would
be willing to give this unit to anyone or group that would come get it
(or pay for the shipping). It does have the AC power cord, the 15 July
1961 manual, 4 BNC cables. It does not have the protective carry case.

If you or anyone you know would like this unit, please email me. I had
it on within the last 20 years, but can make no guarantee for it. I
would like to find a home for this unit.

Regards,

Asa R. Gawthrop
Bridgeport, WV