Benutzer-Werkzeuge

Webseiten-Werkzeuge


en:se-213

SE-213: TLD

Tragbar Leichte Dezimeterstation BBC (Portable Lightweight Decimeter Station), SET 11/2 resp. SE-212; produced by Brown Boveri.

It was not before the World War II years, when interest in using high frequencies in the VHF range for communications arose also in Switzerland.

After a prototype station successfully could be used to establish a communication link between St. Chrischona near Basel and a mountain top station at Jungfraujoch, the War Technical Section (KTA) gave the order to develop a microwave communications system capable of multi-channel transmissions to Brown Boveri Cie. in Baden.

SE-213 / TLD

Technical Data

Power Supply

TLD Speisegerät

  • Mains: Mains power supply TLD-ZT (110, 125, 145, 205, 220, 230, 250 V)
  • Accumulator / batteries: with the optional converter TLD-ZT 11d, the station can be run from 12 V accumulators
  • Generator: pedal generator TLD, marked with a red ring, for emergency operation
  • Generator: Petrol operated generator Motosacoche 1 cyl. two-stroke engine, 220 V, 400 watts

For operation, the station requires a heaters voltage of 14.5V (2.5A) and a plate voltage of 360V (120mA). The station is powered by a mains power supply for stationary use. Alternatively, the station can be powered in the field by means of a gasoline generator or for emergency operation from a pedal generator. The treadmill generator marked with a red ring provides the heaters voltage of 13 volts and 360 V plate voltage.

Dimensions

Total weight of all station material is 214.6 kg

  • Receiver case, case E : 363.5 x 439 x 256 mm, 27.5 kg
  • Accessory case, case Z with the transmitter unit: 363.5 x 439 x 256 mm, 16.2 kg (with morse key, microphone, headphones, spare tubes and transmitter test lamp)
  • Antenna case, case A with transmitting antenna SA, receiving antenna EA; 609 x 458.5 x 250 mm, 15.7 kg
  • two Tripods 58 for the transmit and receive antenna; 660 x 160 mm, 3.6 kg

TLD Umformer

  • Cable case, case K with feeder cables, antenna cables, etc.: 609 x 458.5 x 250 mm, 22.8 kg
  • Power supply unit, case N with power supply unit TLD-ZT: 363.5 x 439 x 256 mm, 30.4 kg
  • Converter, case U with 12 V converter TLD-ZT 11d
  • Treadmill generator, provides the heaters voltage 13 V and plate voltage 360 ​​V, marked with a red ring; 1060 x 345 x 460 mm, 21.8 kg
  • Gasoline generator Motosacoche, 25 kg
  • Fuel case with two gasoline and oil canisters
  • Relay and remote control equipment, case RFA, with the corresponding connection cables

Accessories

  • Standard antenna are two dipole antennas with reflectors; the transmitter unit is mounted directly on the transmitting antenna to keep cables short. The antennas are set up on wooden tripods, these can be stored in canvas cases for transport.

SE-213 / TLD

Operation

Because of the good field performance of the shortwave TL station, the TLD station was constructed following a similar concept with it's portable components.

The main part of the circuitry is found in the receiver case, the R.F. final stage and tuner is located in a small metal case (TLD S) attached to the directional antenna (to keep cable loss low), a mains power supply ZT-TLD, a petrol generator and a pedal-operated generator make also part of the TLD.

The TLD is capable no only of telephony but also of radioteletype connections with the letter printer ETK; in connection with some encryption equipment, automatically encrypted communications were possible.

Senderkasten The main part of electronics is located in the transceiver case, the high power transmitter oscillator with the two LD1 finals is located in a small case attacked to the directional antenna.
The two final triodes in push-pull arrangement will generate 1,5 Watts output power in the 330 - 355 MHz band range.

On the transceiver's front panel, you find next to the station clock the frequency dial, just below the main tuning knob and the mechanical tuning lock. The modes switch is located below the colume control.

Senderkästchen In the right lower corner, the jacks for headphones, microphone ond the Morse key are located, in the left lower corner the jacks to connect the set to a field telephone line, the remote control and audio level control.
In the left upper corner, you find the connectors for the receiver antenna and the cables to the transmitter and power supply, a meter can be switched to control heaters and anode voltages.

Frequency calibration of the TLD station has to be done with the calibration pot on a frequency of 345 MHz. After this, the operation frequency can be set on the spiral dial. It is recommended to maintain a channel spacing of at least 1.2 MHz between the transmission and reception frequencies; the reception frequency should not be chosen in the range 8 MHz below the transmission frequency.

In receiving mode, the frequency of the other station must be located: it is tuned to the maximum deflection of the measuring instrument. After this, when the transmitter tuning lock knob is turned, the automatic frequency correction will be activated, so that the frequency should not „run away“.

The station is intended for local and remote communication: According to it's operational purpose, it should bridge the failure in a wired telephone connection caused by natural factors or combat operations without the communication partners noticing a difference.
Because of only very few multi-channel adaptors were acquired, the TLD station was mostly used for point-to-point connections, which significantly reduced the operational value of the station.

The operating mode switch is used to select the mode:
In position „Ortsbesprechung Mk.1“, the station can be operated like a normal radio, the microphone and headphones are plugged in and you can start to communicate. The transmit switch on the microphone only mutes the transmitter on release. In mode „Ortsbesprechung Mk.1“, the set can be operated with sounding telegraphy (A2). For Hell operation, „Ortsbesprechung Mk.2“ is selected; the Hell transmitter is connected to the microphone and the Hell printer to the headphone connectors.
When the the multi-channel adaptor MK-1 (ZT 11c) is used, the cable stored in the accessory box of the multi-channel adaptor is connected to the five-pin microphone jack („Ortsbesp.Mk.1“); when the six-channel adaptor MK-2 is used, the mode switch is set to the position „Ortsbesp.Mk.2“.

For remote operation, a field telephone line is connected to the terminals La and Lb. In operation mode „Fernbesprechung Tf.“ the set can be operated over the field telephone line in telegraphy; in operation mode „Fernbesprechung Stg.“ teletype signals can be transmitted. In all remote operation modes, when the pushbutton „Leitungsnachbildung“ is pressed, the line level can be regulated; with the switch „Abfrage Draht“ („query telephone line“), a service telephone connection is enabled.

Of course, if the station is used as a relay station, two frequencies are occupied. With the material from the relay case, two TLD radio stations are connected, the station staff is only necessary to control the connections on both sides.

Technical Principle


In the Transmitter section, the AF signal coming from the microphone or a remote control site is fed to a two stage modulation amplifier (V551, V552), in modulated tone telegraphy, the further tube acts as 1000 Hz audio generator.
The transmitter final stage is located in a small metal case, which can be attached to the transmitting antenne while the station is active. Both transmitter RF triodes (V502, V503, two LD1) work in a push-pull arrangement.

The receiver circuit is of single conversion design without RF preamplification: the R.F. signal from the antenna is mixed (D1d / EA50) to a first intermediate frequency of 16 MHz. The oscillator (V 458, LD1) is oscillating on a frequency of 346 - 371 MHz resp. 16 MHz above the operation frequency. After four IF amplifier stages (V281, V 282, V283, V284, four P2d) and the limiter stage (V 285, P2d), the signal is demodulated in the discriminator stage (V286, V287, twoD1d / EA50). The discriminator voltage is amplified (V 459, P2dR, a specially selected P2d is used as a regulator tube for the automatic frequency correction of the receiver oscillator. The AF stages (two P2d) will feed the audio signal to headphones or the field telephone line.

Valve Layout

Receiver: V456, VV457 ([de:[EA50]], mixer); V458 (LD1, oscillator); V281, V282, V283, V284 (P2d, 1st to 4th IF amplifier stage); V285 (P2d, limiter); V286, V287 (two EA50, discriminator); V459 (P2d, automatic frequency correction); V160, V161 (two P2d, AF final amplifier).

Transmitter: V551, V552 (P2d, modulation amplifier); V502, V503 (two LD1, transmitter final stage).

Development

Brown Boveri delivered seven prototype stations with the designation SET 9/2 in August 1943; from the definite version with BBC designation SET 11/2 a hundred sets have been ordered in 1943 and another fifty stations in 1944.

Because of production delays in the war years (problems with valve supply due to the War and export restrictions caused Brown Boveri to produce th R.F. pentode P2 in Switzerland), the station came in service not before the end of WWII in Mai 1945.

The principle operational purpose would have been the replacement of a wired telephone connection destroyed by hostile actions or a nature catatrophy by a microwave link without the communications partners on the telephone taking notice of the fact, they are not communicating over a wired network. This goal could not be reached as the number of multichannel adaptors to transmit several speech or teletype channels over one microwave link was far from beeing sufficient.

Field Use

The TLD found no good resonance with the troops, it was unreliable and the tactical commanders were not aware of the advantages of point-to-point microwave communications:
The station suffered from very frequent dropouts mostly from bad contacts at the valve sockets of the war production valves. Insiders knew, that the valve contacts had to be cleaned with a metal brush or the Swiss pocket knife before switching on the station.

Another problem was the fact, that with it's standard setup, the station could transmit only one channel at a time. The Swiss Army had ordered not enough multichannel adaptors - so the TLD was not perceived useful in practical use: there was no service communications channel to be used in parallel with the main operative communications channel.

The station has been in use until 1960, it has been used for isolated point-to-point connections only. Only with the introduction of the successor, the Brown Boveri made MT 3, microwave communications has found more frequent use with the Swiss Army.

Technical Manuals

Additional Information

en/se-213.txt · Zuletzt geändert: 2019/04/21 17:20 von 127.0.0.1