TA 12 front 2

Bendix aircraft transmitter TA 12.

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  1. The Bendix transmitter TA 12.

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The Bendix transmitter TA 12.

TA 12 front 2

 

This transmitter is originally an American made aircraft transmitter, but also used in the British Royal Airforce (RAF). Aircrafts like Mosquitos.

The  TA 12 has four frequency bands, one for longwave and 3 for shortwave. The funny thing is that each frequency band,  has it’s own VFO,  and only one poweramplifier for all of them, but again 4 output tuning filters with variometer inductance, to match it to the antenna. It delivers about 40 – 50 Watts on phone and CW. Modulation art, A-G2 modulation. In the mid the earial current meter.

The four knobs at the left are the channel preselector tunings, for each wave band one. Left of the knobs are the channel numbers you preselected. In the mid under you can see the knob for preselecting one of the four wave bands.

At the right are the four knobs for tuning, by variometer inductance,  the output filters for matching the transmitter to the antenna.

In the beginning, by lack of the original powersupply/modulator unit, type MT 28 BA , I used a separate modulator, homemade, with 2 valves 807 in the final.  With Ronette crystal microphone. It was doing very well. Also a homemade mains powersupply is used.

But some time ago, I managed to buy one on EBAY, a MT28BA. See the pictures below.

 

Bendix_MP-28BA (1)

 

Sideview with power connector.

 

 

TA12 DYNO

 

Inside view with at the left the Audio PA amplifier valves, in the mid, the modulation transformer.

 

TA12 DYNO BOTTOM

 

View components, at the right, the several fuses and the switch for switching from carbon mic to dynamic mic.

 

The unit had to be cleaned a bit and inspected.  But  nothing was wrong with it. The unit came also with home made cables and control box for working with the transmitter on AM, CW and MCW. For AM I used a T17 carbon microphone. Modulation deph 100 %. The noise level of the rotary transformer is not to heavy. It starts only at CW (contineously) and at AM (during transmitting).

Behind a small panel, you can chose by a switch, between a carbon mic or a dynamic mic. Note that at a type MT 28 B, this provision is not available.

 

Inside the transmitter.

 

TA 12 upper

 

The upper view of the transmitter.

The box at the right is the VFO compartment. At the left upper, one of the four variometer inductances, four each band one.

TA12 relay

View at the HF power amplifier with relay for switching the antenna and HT to the amplifier. The 2 tubes are in parallel.

TA 12 under

The under view of the transmitter. The motor for automatic channel switching at the left is missing. At the right, the VFO box again.

TA12 side

Side view with the four tubes of the seperate VFO parts. Each frequency band  has it’s own VFO part, so also it’s own tube. Left up the power input connector.

The modulator unit is doing very well. In mode AM, I can make almost 100 % modulation depth.  On CW, the tone is very stable. A pleasant way of working with it.

Aerial-Art1a-foto2

Aerial Artificial type 1A

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  1. Aerial Artificial type 1A

Aerial Artificial type 1A

 

The Aerial Artificial type 1A is used in the RAF for aligning the output transmitter stage of the pre-war T 1083 for test purposes. This type 1A is a prewar type.

A schematic diagram is shown is picture 1. Note the different conections for the different frequence ranges.

It can also be used very easily for aligning the TR 1196 or TR 9.

Aerial Artificial  1A

The front and the electrical diagram.

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The front of my set.

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Here you can see the Artificial Aerial, used by the Australian Army in testing the transmitters,

type T-1083.

Aerial to be seen on the left on the shelve.

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TR 9F

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  1. Transmitter/receiver TR 9-F

Transmitter/receiver TR 9-F

In working condition.

 

This is the pre war wellknown “SPITFIRE” sender receiver, type TR 9 F. Although the type 9 F is not used in it, but in the bigger aircrafts like Lancaster etc. for communication between the airfieldtower and the aircraft in close distance.

It is fully working in the 40 meter band with a crystal on 7078 Khz, amplitude modulated, by means of a intercommunication  amplifier, type A 1368. For using this amplifier, I had to make the connectors and the plugboard myself.

Normally a A 1134 is used. By lack of that type, to let it work, I used  the A 1368 intercommunication amplifier.

Question: can anyone tell me about the precise usage of the A 1368 in the RAF?,

Pse some info in the COMMENT at the end of the page.

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The TR 9-F transmitter/receiver in all original condition.

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In front the copies of the plugboard etc, for connecting the amplifier to the TR 9.

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Transmitter part, front..

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Inside the transmitter.

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The power amplifier tube of the transmitter.

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The power amplifier anode coil of the transmitter.

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TR 1196

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  1. TR1196a,
  2. transmitter/receiver
  3. four channels.

TR1196a,

transmitter/receiver

four channels.

 Working condition.

This is a  transmitter-receiver used in airplanes like Lancaster etc. It is a four channel unit. For the receiver, as well as the transmitter, four crystals are used.

It is remote controlled by a switch box. On the picture a replica controll box is used. But the whole unit is working. Supply voltage is 12 volts, which indicates it is an earlier one.

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Transmitter receiver TR 1196 a

Left the connection for the oxygenmask earphones and microphone. In the front the crystal types. At the right the replica remote control box, for choosing one of the four channels and controlling the transmitter.

 

 

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Inside the unit.

Left receiverpart and right the transmitter part. See also there the HF coils for matching the energy to the earial.

 

 

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At the right front the alternator power supply.

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In front a good view on the crystal board of the transmitter.

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In front the earial- and ground connection and the type plate. Also the Air Ministry mark. The white earia is a modification chart.

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Left the transmitter with HF earial coils, for each channel one coil. In the mid the four tuning knobs for pre tuning the HF stages of the receiver for each channel.

 

 

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An overview of the chassis.

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A side view.

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A nice paper layout picture  inside of the housing. It showes the components layout of the transmitterpart for service.