"Concluding Statement on Proving Grounds Trials of the TPU-3M tank intercom device produced by V.I. Lenin factory #197
October 9th, 1940
Leningrad
The commission, consisting of [names and titles] came to the following conclusions after conducting proving grounds trials:
- The TPU-3M prototypes meet the tactical-technical requirements set by the US and ABTU.
- The TPU-3M intercom device allows very satisfactory communications via radio between KV tanks at expected ranges between KV tanks both while stationary or during movement in 1st, 2nd, or 3rd gear, and satisfactory communication in 4th gear.
- No difference could be detected when comparing the legibility of transmissions made through the tank radio directly and those made through the TPU-3M intercom device.
- The TPU-3M intercom allows tank crews to communicate with each other in 1st, 2nd, and 3rd gear and is satisfactory in 4th gear (some words had to be repeated).
- The TPU-3M intercom meets the requirements for use in tanks in terms of simplicity and reliability. The use of an MA type microphone with an activation button is difficult for the crew, especially the driver.
- The commission tested two angled differential throat microphones produced at factory #197 with the TPU-3M. Communication between the commander and radio operator at all speeds was satisfactory. Communication between two tanks, both in motion and stationary, was satisfactory. The commission considers it necessary to use throat microphones with the TPU-3M device.
- Acoustic interference in the KV tank make it necessary to connect the commander and the gunner with an intercom, as voice communication between them is difficult. NIST and factory #197 provided a layout that can provide a connection for a fourth member (gunner) to the TPU-3M device, which gave good results both in motion and while stationary. The commission considers it sensible to add the fourth member of the KV tank crew to the intercom.
Conclusions:
- The commission considers that the TPU-3M tank intercom device produced by factory #197 can be put into production in 1940 after correction of defects.
- The commission considers that in 1941 production the TPU-3M intercom device should be equipped with a throat microphone, for which factory #197 must design a new throat microphone based on the samples tested by the commission.
[signatures]"