Warsaw Radio Mast - Construction

Construction

The Warsaw radio mast was a guyed steel lattice mast of equilateral triangular cross section, with a face width of 4.8 m. The vertical steel tubes forming the vertices of the mast had a diameter of 245 millimetres; the thickness of the walls of these tubes varied between 8 and 34 millimetres depending on height. The mast consisted of 86 elements, each of which had a length of 7.5 metres. The mast had 3 arrays of guy wires, each attached to the mast at 5 levels, 121.78 metres, 256.78 metres, 369.28 metres, 481.78 metres and 594.28 metres above ground. Each guy was fixed on a separate anchor block at the ground and was 50 mm in diameter. To prevent the guy wires from interfering with the radio transmissions, the guys were insulated at regular intervals. The weight of guys and insulators used to anchor the mast was 80 metric tons. An elevator and separate protected ladders were installed in the interior of the mast to facilitate access to the various mast components, including the aircraft warning lamps. The elevator had a maximum speed of 0.35 m/s and required 30 minutes for a trip from the bottom of the structure to the top.

In the lower half of the mast, there was a vertical steel tube, attached to the mast's outer structure with large insulators. This tube was grounded at the bottom, and connected electrically to the mast structure by an adjustable metal bar at a height of 328.68 metres, before transmission frequency change to 227 kHz and at a height of 334.18 metres afterwards. This technique allowed adjusting the impedance of the mast for the transmitter and worked by applying a DC ground at a point of low radiofrequency voltage, to conduct static charge to ground without diminishing the radio energy. Static electrical charge can build up to high values, even at times of no thunderstorm activity, when such tall structures are insulated from ground. Use of this technique provides better lightning protection than using just a spark gap at the mast base, as it is standard at most mast radiators insulated against ground.

The mast was equipped in 16 levels with air traffic warning lights with 200 Watt power. Their height above ground was 49,18 m, 94.18 m, 121,78 m, 161,68 m, 206,68 m, 256,78 m, 296,68 m, 341,68 m, 369,28 m, 409,18 m, 454,18 m, 481,78 m, 521,68 m, 566,68 m, 594,28 m, 634,18 m. On the pinnacle, there was a blinking light consisting of 2 lamps with 1000 Watt power.

A special overhead radio frequency transmission line was used to transfer the signal from the transmitter building to the mast. The transmitter building, situated at 52°22′22.9″N 19°48′25″E / 52.373028°N 19.80694°E / 52.373028; 19.80694 (Konstantynow Transmitter Building), had a volume of 17,000 cubic metres and was approximately 600 metres from the mast. The transmitter consisted of two 1,000 kilowatt units built by Brown Boveri and Cie. An atomic clock was used to generate the transmission frequency in order to provide a very accurate, stable signal source which could be used as a frequency standard by anyone within signal range. The station, which had an area of 65 hectares, also had a 76 metre lattice tower of rectangular cross-section close to the transmitter building, at 52°22′23.6″N 19°48′24.4″E / 52.373222°N 19.806778°E / 52.373222; 19.806778 (Konstantynow Radio Relay Link Tower). This tower was used to provide a radio link for programme feeds from the studio, which ran from the Palace of Culture and Science, Warsaw via a radio relay tower at Wiejca.

To supply power to the station a 110 kV substation was built. The substation was over-engineered due to the strategic importance of the station as Poland's central transmitter. Although the power consumption of the transmitting station was large (estimated 6,000 kW), the substation was capable of supplying much more than was required.

Six small towers were erected around the periphery of the station's grounds in order to support aircraft warning lamps where the guy ropes were located. They are situated at 52°22′17.4″N 19°48′9.7″E / 52.3715°N 19.802694°E / 52.3715; 19.802694 (Signal Tower), 52°21′53.8″N 19°48′6.3″E / 52.364944°N 19.80175°E / 52.364944; 19.80175 (Signal Tower), 52°21′57.1″N 19°47′48″E / 52.365861°N 19.79667°E / 52.365861; 19.79667 (Signal Tower), 52°21′55.8″N 19°48′27.6″E / 52.3655°N 19.807667°E / 52.3655; 19.807667 (Signal Tower), 52°22′6.1″N 19°48′24.3″E / 52.368361°N 19.80675°E / 52.368361; 19.80675 (Signal Tower), and 52°22′8.1″N 19°47′54.4″E / 52.368917°N 19.798444°E / 52.368917; 19.798444 (Signal Tower).

The official name of the facility was Radiofoniczny Ośrodek Nadawczy w Konstantynowie (Radiophonic Transmission Center Konstantynow), Radiowe Centrum Nadawcze w Konstantynowie (Radio Transmission Center Konstantynow) or Warszawska Radiostacja Centralna (WRC) w Gąbinie (Warsaw Central Radio Station Gabin). It broadcast Polskie Radio's Program I.

Approximately ten years after completion of the mast, inspections revealed structural damage caused by wind-induced oscillations at the mast, the backstage insulators and the guys. Repair work was very difficult and replacement of the mast by a stronger construction of the same height was considered. However, this was not realized, as a result of Poland's economic situation. In 1988 the mast was repainted, but this could not be done to the desired extent, as there was not enough paint available.