The UKT FM 66/17 radio is also a product of "Ei-Niš", factory Ei-Pionir, Zemun, made in the 60s. It is intended for maintaining a radio connection in the VHF radio-telephone range (146MHz - 174MHz). the frequency band was assigned Radio device UKT FM 66/17 to users who need radio communication at shorter distances, and divided into several subbands. Ei-Pionir factory offered radio device UKT FM 66/17 to those users. It was made in several versions depending on the purpose (mobile or stationary) and depending on the user (army, police, communal and other services, companies, institutions, and could also be found in the harvesters of the agricultural combine). It is safe to say that this is the most mass-produced radio device , and which was mostly used in the former Yugoslavia. By the way, it is the first European all-solid-state VHF 10W radio device that is powered directly from the 12V vehicle installation. Before that, only STORNO (Denmark) produced a solid-state device that was powered from the vehicle installation at +24V.

The Yugoslav People's Army equipped a large number of its vehicles with this device, and also used them as stationary devices. A special telephone intermediary could be added to the stationary device through which the connection to the telephone network was made. By installing repeater devices (e.g. RRS/FRS 420-4 from the same manufacturer), the KZ Speech Unit KZu-64 formed a radio-telephone network that covered the entire national territory and included that network in its communication system. This radio network was widely used in peacetime, but the principles of communication tactics did not attach any importance to it in war because it is extremely sensitive to the electronic and combat actions of the enemy. About 500 UKT FM 66/17 devices and about 40 RRS/FRS 420-4 repeaters were adapted to work with an external speech protection device, which increased the resistance to electronic reconnaissance. The devices were marked as UKT-FM 66/17K (repeater RRS/FRS 420-4K), and the KZu-64, which was also produced at the Ei-Pionir factory, Zemun, was used as an external device for cryptographic speech protection.

The technical characteristics of this device, which we will present here, refer to the "military" version of the UKT FM 66/17. The devices of other users mostly differed in terms of frequency range and number of working channels. Also, Ei-Pionir made modifications over time and those devices were marked differently, so we have the markings UKT FM 66/18, MRS 320-xx (e.g. 22nd channel MRS 320-22). For police devices, an ISP module according to the CCIR 70 standard is built in for automatic identification and selective calling of participants. This was also the case for other customers of this device.

Radio device MRS 320-22 The UKT FM 66/17 radio device works with frequency modulated telephony (FM) simplex or semi-duplex in the frequency range from 149MHz to 154MHz. The frequency is set with a switch to 22 channels. The distance between adjacent channels was 25KHz, and the maximum deviation of the frequency modulated signal was +/-5KHz. The transmitter radiated an output power of 10W, and the receiver had an input sensitivity of better than 0.6µV. The output LF power in the loudspeaker was 1W. It was powered by a DC voltage of 12V from the vehicle's battery. When the device was used as a stationary device, it was powered from a rectifier that was labeled differently. It consumed 2.3A on transmission, and 700mA on reception at an RF power of 1W.

The entire device is made in transistor technology. The transmitter, as with the UKT FM 66/13, was phase modulated on a crystal oscillator, and in order to obtain the required deviation and operating frequency, the frequency was multiplied Radio telephone UKT FM 66/17 (24X). The resulting frequency-modulated signal was amplified in a transistor power amplifier and sent to the antenna. The receiver is a double super with the first intermediate frequency of 10.7MHz and a classic MF transistor LC amplifier, and the second one at 455KHz. The selectivity in this intermediate frequency stage is controlled by a ceramic filter. The reception frequency was controlled by a quartz oscillator, whose frequency, after multiplication (3X), was lower by the value of the 1st intermediate frequency (10.7MHz). The basic set of devices consisted of: transceiver, microphone, speaker, antenna and antenna lead. Origin: Yugoslavia.