"On the execution of factory trials of the KRSTB radio according to order #319 given on December 14th, 1939
Field trials were carried out in Mytishi-Zagorsk in Moscow oblast. Laboratory trials were carried out in laboratories #10 and 17 of NII-20.
1. Items under trial
Testers were given two complete sets of KRSTB radios. A third radio was used to create interference.
2. Goal of trials
The following was tested:
- Meeting of tactical-technical characteristics.
- Reliability of the equipment.
- Main electrical and design characteristics of the equipment.
3. Conditions of trials
Trials were carried out with tanks in motion: A-7 at 45-50 kph, T-26 at 25-30 kph. The air temperature was -31 degrees Celsius. Radio communication reliability was tested by passing short radio messages.
4. Results of trials
Based on the results of the factory trials, listed in attachments 1-8, it can be stated that:
- The experimental KRSTB radios designed at NII-20 provide reliable communications in motion at a range of up to 20-25 km. While standing the radio range is 30-35 km in telephone mode and 40-45 km in telegraph mode while working with the regular 4 meter long whip antenna as per requirements.
- Experimental radios provide reliable communications on the move with the length of the antenna reduced to 2 and 1 meters with the range of 12 and 5 km respectively.
- In addition to work with the main type of quartz stabilizer, the KRSTB receiver can work with a gradual settings block. This allows communication with unstable radios.
- During trials the equipment worked reliably with the quality of communication deemed superior to all existing types of military radio equipment.
- Laboratory trials showed that the electrical characteristics of the prototypes meet modern requirements for military radio equipment.
- The radios tested satisfy the tactical and technical requirements and provide reliable communications within a tank battalion. There is a 15 Watt (8%) reserve in power draw, meaning that there is a significant reserve in terms of reliable radio range.
- Compared to the existing 71-TK-1 radio, the KRSTB radio has significantly more reliable communications and faster tuning speed due to technically fixed wavelengths rather than gradual settings, which is incredibly useful in a tank where access to the radio is difficult and the commander has direct combat duties to attend to.The gradual settings block attached to the radio allows communication with radios whose transmitters work without quartz stabilizers. The same block can also be used in case of issues with the Z device.
- The KRSTB radio transmitters, receivers and power supply have small dimensions (27 cubic decimeters compared to 95-100 cubic decimeters of the 71-TK-1) and allow the radio to fit into limited space in the turret or hull.Note: factory trials of the KRSTB were performed with the TK-12 device, as the telecode performed unsatisfactorily in July and October trials, and the latest TK-12 device for the KRSTB radio was obtained on October 29th, when the radio was already being tested in real conditions.
- It is possible to promote the experimental prototypes to proving grounds trials.
- The trials should also be considered QA trials.
December 31st, 1939"