Model: 4KVA type  ( this appears to be part of a series).
Modes: CW and  MCW (ICW).
Frequency Range: 600 to 800 metres and 2,000 to 3,000 metres.  (500 to 375 KHz and 150 to 100 KHz respectively)
Power Output:  ?
Frequency Control: Master oscillator (assumed)
Tubes: Two  MT-6 triodes and two MR-6 rectifiers
DC input power: Either 2 KW or 4 KW depending on the transmitter in the series.

Mains power: 110 VAC, 350 Hz, 4 KVA  (this seems to be a very odd mains frequency)
Dimensions: 3 feet deep by  3 ft 9 in wide by 7 feet high
Circa: 1923 . This transmitter was featured in Radio News of Canada,  Dec. 1923. Since the MT-6 tube first saw service in 1919 and the Marconi Wireless Co changed their name in 1925, that verifies the vintage as being accurate.

1) This transmitter was first ordered by Canada's Marine and Fisheries Department as part of their effort to upgrade transmitters at four sites in British Columbia,
2) Does anyone have specs for the MR-6 rectifier tube? If so, please contact: jerry.proc@sympatico.ca
3) The 1923 article cited above is incomplete. It does not indicate the power out or the power into the RF output stage. It speaks of two MT-6 oscillator tubes, one of which could be switched out for voice transmissions. That would mean that the remaining MT-6 would have to function as a MOPA. If not in voice mode, does that mean that one of the MT-6 tubes is being used as an oscillator  while the other is being used as an RF amplifier?  I

4KVA transmitter front view
4KVA transmitter rear view
Images in this table  are from Radio News of Canada,  Dec. 1923

/mt6_tube.jpg mr6.jpg
MT-6  (Photo via Roy Johnson)

Type: Transmitting triode
Circa: Introduced into service in 1919.
Filament: Drawn tungsten filament. rated at  15.5. VDC @10 amps.
Power rating: 400 watts max.
Anode voltage: 12 kv maximum

MR-6 (Courtesy Radiomuseum.org)

Type: Rectifier
Filament 15.5 V@10 amps
Plate 15 kv max
Plate  dissipation 400 watts
Dimensions (WHO) :6.30 x 14.17 x inches
Made by: MO Valve Co. Ltd.;

Contributors and Credits:

1)  https://www.radiomuseum.org/tubes/tube_mt6.html
2) Lewis Bodkin [<5bodkin555(at)gmail.com>
3) Radio News of Canada,  Dec. 1923
4) MR-6 rectifier  https://www.radiomuseum.org/tubes/tube_mr6_ediswan.html

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Feb 6/19