LTT-1 Transmitter (Longwave Telegraph Transmitter)

Frequency range: 260 to 520 KHz
Modes: CW and MCW
Power output: 150 watts CW, 110 watts MCW
MCW sidetones: 500, 700 or 1,000 Hz
Frequency control: 3 preset frequencies controlled by master oscillator.
Primary power 115 VAC , 5.8 amps, 60 Hz.
Transmitter Dimensions: 24" W x 20" D X 44" H
Transmitter weight: 360 pounds
Circa: 1937
Comment: Intended for use with the companion Marconi MSL 59225 receiver.
*** Does anyone have an LTT-1 photo? If so contact : Jerry.proc@sympatico,ca ***

The LTT-1 is identical in most respects to LTT-4 differing mainly in the method of producing high voltage. It can operate on any of three preselected frequencies in the range of 260 to 520 KHz (1150 to 580 metres) by means of single bandchange switch.  A keying relay provides "break in" operation up to 75 wpm. The transmitter itself comprises of a self-controlled master oscillator stage (#10 triode tube) driving a neutralized push-pull RF stage which employs #211 tubes. An additional stage using a #10 tube provides tone generator functionality for MCW mode.


Unlike the LTT-4 which produces its HT using a stack of copper oxide rectifiers, the LTT-1 employs a pair of of 836 half wave rectifiers.


The LTT-1 uses the following vacuum tubes.

ltt4_211_tubes.jpg ltt1_836.jpg ltt4_10_triode.jpg
The LTT-1 employed a pair of 211 tubes in the RF output stage. This type is also known as type VT-4C. (E-bay photo) The 836 half wave rectifier. 
 (Courtesy NJ6V Tube Museum)
10 triode. (Courtesy Tube Depot)
Type 211 characteristics: Transmitting triode. Filament draws 3.4 amps at 9-10 volts. Types "A", "B" and "C" designate filament current. Type "D" has a constant voltage filament (10 volts at 3.25 amps). An "E" type is a "D" type with parasitic-supressor chokes built into the grid and plate leads.

Type 836 characteristics: Half wave rectifier. Max plate voltage = 5000 PIV. Max plate current = 1 amp peak. Filament  voltage  2.5 volts at 5 amps.

Type 10 characteristics: Power triode. FIlament power 7.5 volts @ 1.25 amps. Plate voltage 425 V max @18 ma. Power output 1.6 watts

LTT-1 Operators Manual - PDF  (Courtesy Spectralumni via Laval Desbiens)

Contributors and Credits:

2) Laval Desbiens  <desbienslaval(at)>
3) 836 photo: NJ6V Transmitting Tube Museum
4) 10 triode photo courtesy Tube Depot.

Back to Equipment Listing

Feb 1/17