Radio relay unit HVT–1

The radio relay unit HVT–1 is manufactured in late 50s of twentieth century in factory “Iskra” from Ljubljana. It was meant to be a basic radio relay unit in infantry regiment, and in higher commands it was used for cross connections. It was installed in terrain vehicle Zastava AR–55V with semi–trailer Zastava D–2V with carrying capacity of 0.5 tons. Dependably of use (radio relay or end station) and multichannel telephone units with carrying frequency we have several systems : HVT–1, HVT–4, HVT–12 and HVT–14.

Radio relay unit HVT–1 was consist of these components: transmitter HD–1, receiver HP–1, official channel block HK–1, two helicoidally antennas AS–1 with antenna mast and a tool kit. Beside, HVT–1 radio relay system it was inevitable to have a petrol aggregate AG–3, all necessary cables and tools.

Radio relay transceiver is working in frequency range from 1700 to 2300 MHz working frequency was selected manually (continually) with help of integrated frequency meter. Modulation is impulse repeating from 80 KHz (12,5 μS) and width of 1,8 μS. Space between transmit and receive frequency had to be at least 80 MHz, and space between receive, consecration transmitting frequency of parallel radio relay lines at least 10 MHz.

Output power of transmitter in impulse was 20 W and it can be reduced with artificial antenna for about 10 dB. Range is expressed with carried value and it was max of 163 dB. Basically, distance between, radio relay station must not exceed 50 km. On an radio relay unit, on the end station is connected a multichannel telephone unit (unit of carried frequencies) usually type FNT–15. Range of high frequency channels (modulation band frequency) of this device had to be from 3,6 KHz to 23 KHz, and official channel from 300 Hz to 2600 Hz. Unit was powered with voltage of 220 V with petrol aggregate AG-3 or from electric grid. Place of origin: ex Yugoslavia.

RDM-63 Radio Relay Set

For equipping of infantry battalion with radio-relay device for connection to the commands regiment. Generalstaff of Yugoslav People's Army was in '60-year bought from Czechoslovakian factory "Tesla" in Přelouč mono-channel VHF Radio relay devices RDM-63. The set of the devices was delivered in a wooden packing case in which are, in addition to transceiver, was putting all other components. Packing case was also served for transport: manual, packed horses or vehicle.

Over Radio relay set RDM-63 was carrying one phone channel, where it was available official connection between the operators. Usually was connecting on the battalion field switchboard type MP-10. He has worked in the frequency range from 235 MHz to 260 MHz, the frequency modulation and realized the power output of 100 mW. He was powering on with voltage of 6 VDC from lead batteries. The protection of connection have got with small power device and with the using of directional yagi antenna. This device have not stay long in equipment of the Yugoslav Army, because it was eliminated by Yugosav mono-channel Radio-relay device RRU-1.

Technical Specification: Frequency range: 235 MHz - 260 MHz; Modes of Operation: FM (frequency modulation); Output Power: 100 mW; Power Requirements: 6 VDC lead battery. Place of origin: ex Czechoslovakia.