SOV - PAR-3 (přívodná letecká radiostanice)

Together with the introduction of jet aircraft into the armament of the Czechoslovak Air Force, it was soon proceeded to equip airports with the necessary ground security technology, enabling flights even in difficult weather conditions.

Radionavigation and light technical security was provided by the Airborne Security Service (LZS), in the early days organized into LZP (Airborne Security Means) companies and LZS radiotechnical platoons.
In order to unify procedures and thus the necessary equipment for Securing landings in difficult visibility, a standard was adopted from the USSR, designated OSP-48 / Oбеспечение Слепой Посадки ОСП-48.


One of the primary assets was two non-directional radio beacons, referred to at the time as "Feeder Radio Stations"
(in current Aeronautical Radio Navigation Service terminology they are referred to as Location BeaconsNDB/Non Directional Beacon)/L (Locator).

They were deployed on the landing direction in the VPD axis.
According to OSP-48 standard, it was located at a distance of
4,000 m ahead of the "Remote Incoming Radio Station" (RIRS) threshold.
a
1 000 m in front of the "Near Incoming Radio Station" (NIRS) threshold.

In the first years of the ground security devices (from 1952) various "prey" types of transmitters were used - for example, from the company. Lorenz 1500W, 800W and 100W.

Gradually, new "uniform types" began to be imported from the USSR.
The first type supplied was the PAR-3 radio station.
All versions were shipped from the USSR as mobile on ZIS-151 (and less frequently ZIS-150) cars.

The crew consisted of 4 soldiers:
- station chief / senior radio mechanic;
- driver-power supply engineer / electromechanic;
- 2 operators / radio mechanics.

PAR-3 system composition:

1. box car.
PAR-3s were mainly fitted to the bodies of ZIS-151 cars.
The box body itself was still of so-called "wartime" construction - i.e. it was not yet a KUNG, but a wooden "slatted" and almost flat, "plated" roof.

Dimensions of the ZiS-151 (ZiS-150):
- Length: 7400 mm (7000 mm)
- width: 2235 mm (2320 mm)
- height: 3177 mm (3177 mm)

The superstructure itself was divided into two functional sections, each with an entrance door on the right side.

a) Front part - "source/aggregate":

This housed a pair of 3 kW type L 6/3 gasoline-powered, liquid-cooled, AC-operated power generators. The petrol tanks (4x 40 litres) for their operation were mounted on the front side of the superstructure - above the driver's cab.

b) Rear compartment - "instrument":
The radio transmitter and the operator's table were located at the "dividing" bulkhead.
There was also a crew compartment - on the left side there were 2 folding "beds".
At the rear head of the compartment was the transmitter of the MRM-48 "Marker" radio beacon.

Its antenna was folded on the roof of the superstructure during transport.

Under the floor of the superstructure in the centerline was a wooden box in which the parts of the folding antenna mast were stored.

The radio was also built into a box P V3S.
******

2nd power source
- In the basic version from the USSR, a pair of 3 kW power generators (generator RGN-3000 (supplying 3000V and 20V) powered by a gasoline-powered, liquid-cooled engine L-6/3), working alternately, were used to power the radio station.
This version was without mains power capability.
- Another, modified version with only 1 power plant and a selenium rectifier with the possibility of supplying 3x 380 V from the external mains.
(This was also how the station was powered when the station was built into the building and then it was possible to power the station in case of a power failure.

The power supply also included a 5NKN-100M battery
and rotary converters:
RUK-300V(for 26/18V to 750/500V) and RU-11B (12V to 212V).

The power consumption of the station was about 3100 W.

3. PAR-3 transmitter with antenna system
The station was delivered in five versions with different frequency ranges:
a) PAR-3, PAR-3B, PAR-BM range 250 - 750 kHz
(b) PAR-3BR range 250 - 1050 kHz
(c) PAR-3BR with modification 250-1300 kHz range

Types of operation:
A 1 (unmodulated telegraphy),
A 2 (modulated telegraphy)
A 3 (phonics)

The accessories of the radio station included:
- automatic telegraph key APS-2
- manual telegraph key
- microphone
- headphones
- vlnoměr

The automatic key APS-2 (Aппарат Подачи Cигналов (/ АПС-2)) was used to transmit the call signs of the feeder radio station(Morse marks), (An electric motor via worm gear "drove" the disc on which the mark was set. The switching contacts were then "keyed" via a relay during A 2 operation.

(The station could be used for so-called one-way communication with the aircraft - in case of a failure of its on-board radio station, the "feeder" operator could "communicate" instructions from the VS or flight controller to the pilot via the microphone. (The on-board radio compass had an "intercept").

The transmitter power at A 1 was 400 to 500 W. (The end tube was of the GKE-500 type, as in the RAF KV-5).

- Antenna system
was of the so-called "umbrella" type, consisting of a folding tubular mast 17.5 m high, from the top of which 6 wires (60° each) were stretched evenly - de-isolated, anchored into the ground.
Under this antenna system, a "network of 6 counterweights" was stretched in a beam-like manner, about 1m above the ground. (If touched during the carriage, there was a risk of "burning" by the RF current and it was very difficult to heal!)

4th US-P receiver
It was used to control the listening of the transmitter itself. The basic receiver was US-P with headphones.
Frequency range 175 - 12000 kHz.

5. wavemeter (frequency meter)
Used to check the frequency setting of the transmitter.

The PAR-3 (like other Soviet-designed radios from the wartime and just after the war) did not have scales "calibrated" to frequency, but only scales in parts - "fixes". On the panel was a table of "parts" and the corresponding frequency/frequency. On the "change" - a multiplication (25x) had to be made between the data in the table and this corresponded to the frequency). Therefore a check with a frequency meter - a wave meter - was necessary.

6. MRM-48 radio transmitter with antenna
The radio beacon transmitter MRM-48("Marker") was used to mark/mark the passage of the radio station (among other things, it warned the pilot that after crossing the "far" he was about 4 km before the VPD threshold and switched the radio compass or automatic radio compass (e.g. ARK-5) to the "near", after crossing which he was about 1 km before the VPD threshold.
The "Marker" antenna consisted of a dipole with a reflector "on the ground" and provided directional upward rejection of radio waves in a narrow cone. When moved, the antenna was folded on the roof of the car.

7. TAI-43 field telephone
The telephone TAI-43(or later TP-25) was used for telephone communication of the PAR-3 crew with the air traffic control office, the command post of their own unit, etc.

****

After the inclusion of the more powerful PAR-7 (after 1958), the PAR-3 was used for "near" or as a backup "far" station.


Source
Flight-51-70 - RTZ Systems and Resources, 1967 Edition I and 1982 Edition II.

Pohled na panel vysílače PAR-3
(kopie z předpisu)

Koncová elektronka GKE-500 měla nejen zvláštní tvar, ale byla i veliká. (Na přiložené fotografii je pro srovnání vidět ruka.
Byla umístěna v samostatné, dobře chlazené části (vpravo od vlastní skříně). Držák tvořil zvláštní "prstenec", odpružený soustavou čtyř vinutých pružin.
Vodiče pro katodu, mřížku a anodu byly z měděného lanka, isolované "korálky" a ukončeny očky.

PAR-3BM in ZiS-151