The R-104M is an Amplitude Modulated ( AM ) vehicle or Man packed transceiver. It consists of : a transceiver, an antenna matching unit, a battery pack, a vehicular power supply and related accessories. The transceiver is housed in a metal case, 35 x 42 x 24 Cm, weighing 25 Kg with a removable front cover. the cover protects the various knobs and controls that operate the radio. It can be recognised by a leather carrying strap on top and a large bevelled frequency window. The matching unit is also housed in a metal case with a removable top which protects the cable connections and the two 2.4 volt DC batteries. The top also stores the 4 meter whip antenna. The vehicle power supply is housed in a metal case and has two cable connector jacks and two wire connectors for power. The accessories consist of two power cables, a handset / headset, a CVC helmet. a repair kit and the various antennas.The set is capable of AM / CW and covers the frequencies from 1.5 to 4.25 MHz. It has continuous antenna tuning and a transmitting range of 50 Km. It can be powered by 12 VDC from a vehicle battery or 4.8 volts from rechargeable wet cells.
The matching unit is 17.8 x 6.3 x 6.3 and weighs 2.2 Kg. , The Battery pack is 35 x 15 x 20 Cm and weighs 10.5 Kg. , and the vehicle power supply is 10 x 16.5 x 21 Cm. and weighs 9 Kg. The set can be remotely operated from 300 meters away using a field telephone. This set can communicate with the R-102, R-103, R-112, R-118 and the R-130 systems.
The set is used in Motorised Rifle and Artillery Regiments and also is used by the Reconnaissance, Signal, and chemical elements of a tank battalion. It has been replaced by the R-104 M which has an expanded frequency range of 1.5 to 4.5 MHz. These sets have been replaced by the R-129 for manpack operations and by the R-130 for vehicle operations. The set is capable of AM / CW and covers the frequencies from 1.5 to 4.25 MHz. It has continuous tuning and a transmitting range of 50 Km. It can be powered by 12 VDC from two 6 volt batteries or 4.8 volts from rechargeable wet cells In low power operation the power output is 1 watt for AM voice mode and 3.5 watts for CW. In the high power mode, 10 watts are provided for AM voice and 20 watts for CW. In the high power mode and with the proper antenna, etc the set has a range of 50 Km ( 31 Miles ) The continuous tune characteristic of this set makes it possible to tune up to 275 fixed frequencies by using the graduations on the frequency dial.The set is designed to use a wide range of antennas to include a 4 meter whip, a log wire, a 50 meter wire, dipole and an 11 meter telescopic mast and an inverted "L".
I get a R-104 HF radio well functions as new from Gunter Fietsch.This radio is frontmarket German language.It was for old DDR army.
When I testing the radio R-104m on the amateur band 3.700Mhz,the transmitter was correct to the scale (40hz off).The problem was the receiving on 3.700Mhz.The receiver stay on 3.994Mhz (6Khz lower).After controlling the x-tall mixer (690Khz) it was 690.10Khz,and OK.The result was the IF 690Khz,changed to 696Khz?possible 60 years have changed the condensers in the IF trafos.I melting of the iron IF covers,and tune the IF to the correct freq.Now,the unit transmit and receive on same freq.
Later, when the unit was testet in the field,the microphone signal was very low.It was modulated only 20-25%.Second, it lost the antenna tuning to. The negative voltage -280v from power disapeared.The transformer coil winding for this voltage was broken. Demounted it and rewinding the transformer. This negative voltage is importent, giving ca -13v to the suppressor grid. The transmitter is modulated via the grid. Now the modulations reached ca 95% modulation.The second problem was the oscillator box included the components, 75-76 and 79, the main oscillator for rx and tx.Here one of the components shortcut to earth inside the box. It is always a little tricky this radios to get inside the box .
Old vibrator power. (New with transistor converter)
Field day 10-05-08 testing the R-104 HF stations in the amateurband 3,640Mhz.It was connections daylight, 90km.Via the intern antennatuner,it work with a 14m longwire horizontally ca 2-3 meter over the ground.
This site was last updated 03/29/11 Home