SRR-4

All mode (AM, FM, CW) military VHF surveillance receiver covering 20-100 MHz
in one band.  Designed by Mallory, but made under contract by others as well. Many tubes are in sealed pull out modules and cannot be accessed directly.

The following courtesy of Crypto Museum:

The SRR-4 was a VHF surveillance receiver, developed by the Technical Services Division (TSD) 1 of the US Central Intelligence Agency (CIA) around 1958.  It covers 50 - 200 MHz in a single band and can demodulate AM, FM, CW and modulated CW signals. Although the receiver was intended for general communications applications, it was typically used for intercept, surveillance, band monitoring, direction finding and in particular for the reception of covert listening devices ( bugs). The receiver is built with 12 subminiature tubes and has an internal Power Supply Unit (PSU) that is built with 3 transistors. The device can be powered by a 12V DC source, or directly from a 110/220V AC source by connecting the appropriate power cable to the power socket. 

In addition, the SRR-4 can be powered by LT and HT batteries that are fitted internally. A complete set consists of the SSR-4 receiver, a telescopic antenna, various power cables, a spares case and a small instruction manual, all nicely packed inside a leather catalog-type carrying case

See similar models R744A and R744. 

Vous pourrez trouver sous ce lien 399 modèles d'appareils, 351 avec des images et 210 avec des schémas.
Tous les appareils de MILITARY U.S. (different makers for same model)