RM31 radios
In the post-war period, several types of shortwave (HF) radio stations were used in the Czechoslovak army. In addition to the Germans, who remained in our territory after the Wehrmacht, the British ( WS19) a sovietske ( RBM1 and RBM-5). Their common disadvantage was that they were represented only in relatively small numbers, insufficient for military needs. Therefore, the development of a new, modern radio station for the needs of the army was started. The basic requirement was a range of at least 30 km day and night, the possibility of operation by telegraphy and telephony and simple operation.
The design team chose the British radio station WS 19 as a model, took over the cast chassis from the German design school, and the use of a crystal-controlled frequency control panel contributed to the solution, which greatly simplified operation. The development of WS19 began in 1941. The radio station was designed as a receiver-transmitter in a transceiver connection, which means that some parts are used for both the receiver and the transmitter. For this reason, it is possible to operate the radio station only in simplex mode, i.e. the radio station receives or transmits signals. The WS19 scale was relatively coarse, which complicated tuning to the operating frequency. The use of a crystal-controlled frequency control panel in RM31 with a tuning step of 5 kHz simplifies and refines tuning. To tune the radio station to one of the 800 channels, it was enough to switch 4 switches and select the appropriate type of operation (telegraphy or telephony). The most modern tubes, American seven-pin with battery power, were used as components. The only exception was the end tube of the transmitter, RL15A, which was of Czechoslovak construction. The original American tubes were replaced by Czechoslovak copies. However, these suffered from imperfectly mastered technology and were therefore relatively faulty. The most common disorder was the microphone, which manifested itself as a sharp ringing sound when you tap the tube or the whole radio station. The circuit solution was very modern for its time. 30 crystals were enough to select one of the 800 operating frequencies (channels). Another crystal was designed to fine-tune the receiver and transmitter, and the last was built into the receiver's IF amplifier, where it allowed the bandwidth of the received band to be changed. The change in bandwidth made it possible to suppress interference, especially during telegraph operation, and at that time practically only separate receivers and receivers of large radio stations were equipped with it. There were also some changes during production, the most striking was the replacement of the measuring device for tuning the antenna in the antenna part with a light bulb.
Version RM31P was the most widespread version, the operator consisted of 3 men. It was divided into 3 loads. It served to connect motorized rifle regiments with the division and as a personal radio station for all-army commanders of higher units. Own radio station, manual dynamo for transmitter with stand and 2.4 V/10 Ah battery for powering the receiver, vibration converter, antenna part and accessories (antennas, spare parts). The operation of the radio station with a rod antenna was also possible while moving, but all members of the operator were connected to each other by power cables. These could be disconnected by a simple jerk without damage, which happened very often during transfers, especially at night.
Technical data of the basic radio station:
Operating frequency range 2,000 to 5,995 MHz
Transmitter power 6 W for A1 and 1.5 for A2, A3
Receiver sensitivity 3 µV for A2, A3 and 1 µV for A1
Types of operation A1 - unmodulated telegraphy
A2 - modulated telegraphy (1 kHz)
A3 - amplitude modulated telephony
Weight of individual loads load I. 18 kg 350 x 230 x 300 mm
burden II. 22 kg 365 x 440 x 170 mm
burden III.21.5 kg 230 x 540 x 260 mm
The accessories consisted of: handset, microphone, headphones, telegraph key with strap for attachment to the foot, measuring device for checking the electronics in the radio station, spare tubes, insert into the microphone, rod antenna 1.8 m, rod antenna 4.8 m and wire dipole 2 x 2 + 7 m, version RM31A aj 2 x 8 + 4 + 7 m.
RM31 with antenna part and measuring device for electronic control
The radio station was produced in versions:
RM31P - infantry
RM31A - automobile
RM31S - for self-propelled guns
RM31T - for command tanks, was supplemented by a radio station RM31-50 operating in the VHF band
Radio range:
fónia
day - 15 to 25 km
night - 4 to 7 km
telegraphy
day - 50 to 60 km
night - 20 to 30 km
The other versions consisted of its own radio station, rotary converter, antenna part, two batteries 5NKN45 and accessories. They were mounted according to the type of mobile device for which they were intended. The antenna part and the radio itself were the same for all versions.
The radio station was used from the beginning of the 50's until the end of the 60's. One of the largest deployments of radio stations in "combat" use was during the flood on the Danube in 1954, when soldiers provided flood reports directly from the Danube. The radio stations were placed on 6 local inflatable boats of the "Dinghy" type anchored by the shore and the staff was under a tent built on this boat. From the mid-60s, infantry and later automobile and tank versions began to get into the hands of radio amateurs through Zväzarm, where they were used until the early 80's and sporadically, especially lovers of nostalgia are still used. At the same time, radio amateurs routinely communicated with these radio stations throughout Europe.
Literature:
History of the Liaison Force, VHU Prague 2007
Handbook for non-commissioned officers of the liaison army, Prague 1962
Brief data on links used in ČSLA, Prague 1965
In the post-war period, several types of shortwave (HF) radio stations were used in the Czechoslovak army. In addition to the Germans, who remained in our territory after the Wehrmacht, the British ( WS19) a sovietske ( RBM1 and RBM-5). Their common disadvantage was that they were represented only in relatively small numbers, insufficient for military needs. Therefore, the development of a new, modern radio station for the needs of the army was started. The basic requirement was a range of at least 30 km day and night, the possibility of operation by telegraphy and telephony and simple operation.
The design team chose the British radio station WS 19 as a model, took over the cast chassis from the German design school, and the use of a crystal-controlled frequency control panel contributed to the solution, which greatly simplified operation. The development of WS19 began in 1941. The radio station was designed as a receiver-transmitter in a transceiver connection, which means that some parts are used for both the receiver and the transmitter. For this reason, it is possible to operate the radio station only in simplex mode, i.e. the radio station receives or transmits signals. The WS19 scale was relatively coarse, which complicated tuning to the operating frequency. The use of a crystal-controlled frequency control panel in RM31 with a tuning step of 5 kHz simplifies and refines tuning. To tune the radio station to one of the 800 channels, it was enough to switch 4 switches and select the appropriate type of operation (telegraphy or telephony). The most modern tubes, American seven-pin with battery power, were used as components. The only exception was the end tube of the transmitter, RL15A, which was of Czechoslovak construction. The original American tubes were replaced by Czechoslovak copies. However, these suffered from imperfectly mastered technology and were therefore relatively faulty. The most common disorder was the microphone, which manifested itself as a sharp ringing sound when you tap the tube or the whole radio station. The circuit solution was very modern for its time. 30 crystals were enough to select one of the 800 operating frequencies (channels). Another crystal was designed to fine-tune the receiver and transmitter, and the last was built into the receiver's IF amplifier, where it allowed the bandwidth of the received band to be changed. The change in bandwidth made it possible to suppress interference, especially during telegraph operation, and at that time practically only separate receivers and receivers of large radio stations were equipped with it. There were also some changes during production, the most striking was the replacement of the measuring device for tuning the antenna in the antenna part with a light bulb.
Version RM31P was the most widespread version, the operator consisted of 3 men. It was divided into 3 loads. It served to connect motorized rifle regiments with the division and as a personal radio station for all-army commanders of higher units. Own radio station, manual dynamo for transmitter with stand and 2.4 V/10 Ah battery for powering the receiver, vibration converter, antenna part and accessories (antennas, spare parts). The operation of the radio station with a rod antenna was also possible while moving, but all members of the operator were connected to each other by power cables. These could be disconnected by a simple jerk without damage, which happened very often during transfers, especially at night.
Technical data of the basic radio station:
Operating frequency range 2,000 to 5,995 MHz
Transmitter power 6 W for A1 and 1.5 for A2, A3
Receiver sensitivity 3 µV for A2, A3 and 1 µV for A1
Types of operation A1 - unmodulated telegraphy
A2 - modulated telegraphy (1 kHz)
A3 - amplitude modulated telephony
Weight of individual loads load I. 18 kg 350 x 230 x 300 mm
burden II. 22 kg 365 x 440 x 170 mm
burden III.21.5 kg 230 x 540 x 260 mm
The accessories consisted of: handset, microphone, headphones, telegraph key with strap for attachment to the foot, measuring device for checking the electronics in the radio station, spare tubes, insert into the microphone, rod antenna 1.8 m, rod antenna 4.8 m and wire dipole 2 x 2 + 7 m, version RM31A aj 2 x 8 + 4 + 7 m.
RM31 with antenna part and measuring device for electronic control
The radio station was produced in versions:
RM31P - infantry
RM31A - automobile
RM31S - for self-propelled guns
RM31T - for command tanks, was supplemented by a radio station RM31-50 operating in the VHF band
Radio range:
fónia
day - 15 to 25 km
night - 4 to 7 km
telegraphy
day - 50 to 60 km
night - 20 to 30 km
The other versions consisted of its own radio station, rotary converter, antenna part, two batteries 5NKN45 and accessories. They were mounted according to the type of mobile device for which they were intended. The antenna part and the radio itself were the same for all versions.
The radio station was used from the beginning of the 50's until the end of the 60's. One of the largest deployments of radio stations in "combat" use was during the flood on the Danube in 1954, when soldiers provided flood reports directly from the Danube. The radio stations were placed on 6 local inflatable boats of the "Dinghy" type anchored by the shore and the staff was under a tent built on this boat. From the mid-60s, infantry and later automobile and tank versions began to get into the hands of radio amateurs through Zväzarm, where they were used until the early 80's and sporadically, especially lovers of nostalgia are still used. At the same time, radio amateurs routinely communicated with these radio stations throughout Europe.
Literature:
History of the Liaison Force, VHU Prague 2007
Handbook for non-commissioned officers of the liaison army, Prague 1962
Brief data on links used in ČSLA, Prague 1965