Modes: AM only
Frequency Range: 3 band HF range. Specifics unknown at this time.
Frequency Control: 3 crystal controlled frequencies
Circa: ?
Comment:  S/N 329 , pictured here,  has been fitted with a Bilely crystal cut for 3203 KHz.

These were the low band HF frequency assignments in the 1940's, the likely era of the receiver.

1600 - 1712 Geophysical; relay; police; government; marine; experimental; fire;
aviation; motion pictures.
1750 - 2050 Amateur radio.
2004 - 2500 Experimental visual and relay broadcast; police; government; ship harbour;fixed; misc.
2504 - 3497 Coastal harbour; government; aviation; fixed.
3500 - 4000 Amateur radio.
4005 - 6000 Government; aviation; fixed.

Can anyone provide more info? Contact: jerry.proc@sympatico.ca

lfr_2sb_front_ panel.jpg
By experimentation, the “Q in” and “Q out” switch is simply a squelch type circuit with a slotted pot on top of the chassis for sensitivity adjustment. It sets the signal strength threshold that allows the audio to pass through and be audible in the speaker. It can be set for complete audio cutoff with no antenna connected and full audio with the antenna connected. The “Q” likely means “Quieting.
The interconnection panel is at the back of the receiver. 
The internal nameplate says "Canadian Marconi Co", Vibrator Unit Assy Rating -6V Type 54780 S/N 159 Spec. 56049 
Note the circular crystal on the phenolic board just to the right of centre. The three round cans at the right screw off the base, exposing the coils, which look like they’re for the low HF range. 
LFR-2SB S/N 329 photos courtesy E-bay. Here is the topside nameplate data:

TYPE LFR-2SB, 57830  SERIAL 329
PAT’D (blank)  SPEC 58104


This hand drawn sketch of the connections was found inside the receiver when it was purchased on E-bay.  

Contributors and Credits:

1) Meir Ben-Fror WF2U <wf2u(at)ws19ops.com>

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Feb 4/08