AN/URT-3 Transmitter Restoration Project

1/4/2009 UPDATE - It's alive! (without the booster until I figure out how to get 3-phase power to it). I still need to align the freq. synthesizer and work on the auto-tune, but I have 100 w out and modulation. Major thanks to John Dilks for providing extender cables! You should hear this beast when all 23 rotary solenoids start clacking madly and the auto-tune motors are whining away.

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Kludge test set-up - Left to Right:   RF amp on desk, HV supply on floor, modulator in rack, oscillator on cart!

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RF amplifier on the desk

HV supply (MVPS), 1300v & 500v, on the floor
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LV supply and modulator in the rack
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RF oscillator on the cart, with mike wires stuck into modulator connector.

3/19/2008 Acquired  - Early 1950's autotune HF transmitter - 100/500 watt, 136 tubes, dozens of relays
                                   300kc - 26 mc AM/CW/FSK
                                   More Info Here

Restoration Progress pages

RFA - RF amp

LLRM - 100w Modulator

RFO - Oscillator

Accessory Items Page

            LVPS - Low Voltage power supply

MVPS - 100w HV power supply

Transmitter Cabinet

            HLRM - 500w modulator

HVPS - 500w HV power supply

Booster Cabinet

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Before delivery
100w transmitter rack
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booster rack for 500w operation
4-125 modulators & 3kv HV p/s
blowers in base
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ACG - antenna tuner control unit
WANTED - I am looking for Antenna Tuning Unit, Extender Cables, Remote Control, & Test Units

See Accessory Items Page

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xmtr rack upper
note drain tubes from condensation drip tray at top

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xmtr rack lower
blowers in base
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xmtr rack external connections in base

Nifty plug-in scheme for modules, but you really need the extender cables to work on anything.


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upper xmtr rack module connections
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PA to xmtr rack connections
power, control, HV, & RF
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PA module plug-in
power, control, HV, & RF
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RFA - PA - 4-400 socket at upper left
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RFA - PA MF tank slug tuning
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LLRM - 100w modulator
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MVPS - 100w HV p/s with 3B28's
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RFO - freq synthesizer
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above - manual freq control
below - 10 preset freq
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Uh-oh - serious mouse poop in the oscillator. This photo is after I'd cleaned it up some!
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LVPS - control and LV p/s
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LLRM - mouse nest
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HLRM - 500w modulator with 4-125's and mouse nest
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HVPS - 500w HV p/s missing 3B28's
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HVPS - another mouse home