Monday 17 December 2018

71-ТК-3 Radio Trials

"Report #027
September 28th, 1940

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


Two A-34 vehicles, #0816-4 and 0618-3 were equipped with the 71-TK-3 radio. The radio was installed in the front of the hull with the following placement of components (see photo):
  1. Receiver with the frame on two mounts in front of the bow gunner/radio operator's seat.
  2. Transmitter with the frame to the right of the bow gunner/radio operator's seat between the front suspension spring and first suspension spring shaft.
  3. RUN-10 converter and battery are under the receiver on the front balancer beam.
  4. RUN-75 converter on the right under the transmitter.
  5. The antenna is installed in the right sloped hull wall. The central switch is under the radio in a bustle near the antenna port.
  6. The switchboard and distribution panel are located on the front sloped plate between the driver's hatch and the MG mount.


Trials were carried out between height 133.5 and Rubezhnoye on the Saltovo highway between 09:00 and 17:00. The weather was sunny, dry. Vehicle #0618-4 with radio #2270 was located near height 133.5. Vehicle #0618-3 was driving towards Rubezhnoye. The following data was obtained during trials:
  1. When both vehicles are driving at 3rd or 4th gear at any engine RPM, bidirectional communication remains stable at a distance of 15-16 km with 100% success rate in transmission of control messages.
    When distance increased past 16 km, communication became unreliable. When still, the range is up to 26 km.
  2. Trials showed that using the radio equipment is easy and simple, both in motion and while stationary. However, the existing layout has the following drawbacks which make access to certain mechanisms difficult:
    1. Due to a small gap between the transmitter and receiver, access to the tightening nut of the idler is impossible.
    2. Due to a small gap between the right friction clutch lever and the receiver side, the driver's hand can clip the side of the receiver, which can lead to an accident.
    3. The placement of the transmitter along the right side of the vehicle with the existing seat makes seating cramped in summer conditions and will be impossible in winter conditions.
    4. While tuning the receiver the radio operator can lean forward and hit his head on the distributor panel, which is installed on the upper front plate.
  1. As trials show, this placement of the radio on the A-34 gives a maximum range of communication between two tanks as follows:
    1. During motion of both vehicles: 15-16 km.
    2. With both vehicles stationary: 25 km.
  2. Measurement of antenna current shows that the greatest magnitude of current is obtained with the current layout (third variant).
  3. Consider the current layout acceptable from the standpoint of using the radio equipment.
  4. The difficulty in accessing mechanisms of the vehicle cannot be accepted and must be corrected.
  5. The distribution panel location is unsatisfactory.
  6. The radio operator's cramped workstation is unsatisfactory.

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