T-34 Radio Trials

"Record #030 

October 22nd, 1940

RE: field trials of radio equipment on T-34 vehicles

Basis: item 16 of the minutes of the commission meeting of September 28-30th, 1940

Items under trial:

Vehicle #608-01 with a 71-TK-3 radio transmitter #2205, receiver #2251, RUN-75 #31140, RUN-10 #30905, TPU-3M #5.

Vehicle #547-29 with a 71-TK-3 radio transmitter #2266, receiver #2244, RUN-75 #30248, RUN-10 #31916, TPU-3M #8

Installation of the radio is in the front of the vehicle according to the conclusions of the commission on September 28th.

Goal of trials:

1. Establish the radio range between two vehicles in motion.
   Notes: the trials are a part of the trials of 10 vehicles requested by item 16 of the commission's concluding statement.
2. Determine the reliability and range of the radio communication if the antenna is tilted (middle position of the antenna mount).
3. Ability to work through the TPU-3M.
4. Reliability of the radio mounts.

Methodology:

1. Trials are performed outside of industrial zones at three preset frequencies (160, 190, 225).
2. The maximum range with both the tilted and straight antenna is defined as the distance between vehicles at which reliable bidirectional communication between two moving vehicles is possible at any speed and engine RPM. Reliable communication is defined as understanding of 5-6 word radio messages transmitted twice.
3. The ability to work through the TPU-3M is tested in motion through the internal circuit and through the radio from microphones #1 and #2.
4. The reliability of the radio mounts is determined during the communications trials.

Record and results of the trials:

Trials were performed at the section of Saltkovo highway between height 133.5 and Nepokrytoye between 12:00 and 16:00. The weather was clear, +6-8 degrees. The ground was soft from rain.

Vehicle #608-1 with radio set #2205 was located near height 133.5. Vehicle #547-29 with radio set #2266 was driving towards Nepokrytoye. The following results were obtained during trials:

1. Communication was reliable and uninterrupted in 3rd and 4th gear at any engine RPM at the following distances:
1. With the antenna tilted at 45 degrees: 5-6 km.
2. With the antenna straight: 17-18 km.
2. When stationary with the antenna tilted at 45 degrees the range was 10 km. The radio range with the antenna vertical while stationary was not checked past 18 km.
3. During motion communication through the TPU-3M circuit was satisfactory. With the same conditions as using the radio, communication through microphone #1 and microphone #2 was satisfactory within 17-18 km. The sound volume was reduced when using the TPU-3M compared to just using the radio directly.
4. No defects in attachment of individual components or installation was observed during trials.

Conclusions:

1. A 71-TK-3 radio installed in the front of a T-34 tank provided bidirectional radio communications within a range of up to 17-18 km in motion while working with the TPU-3M.
2. The conclusions regarding the maximum range in motion that can be recorded in the technical requirements will be obtained when all ten vehicles defined in item 16 of the conclusions of the commission on placement of the radio into the T-34 tank made on September 30th, 1940, are tested.
3. Because the TPU-3M prototypes were installed on the vehicles without appropriate trials and approval, and considering the decrease in volume while working with the radio through the TPU-3M, the decision regarding the feasibility of using the TPU-3M on vehicles should be made after conducting separate trials.

[Signatures]

October 22nd, 1940"

RGVA 31811-2-1130 pp.176-177