CD-12 Transmitter-Receiver


Except for differences in frequency control, the CD-12 was the version of the FR-12 built for the Canadian Army. Both the CD-12 and the FR-12 came with a swing-down key attached to the front panel. In addition, the CD-12 had an accessories lid. Each set transmits in the 2 to 4 MHz band at a 15 watt power level on CW and lower power levels on MCW and Phone. The CD-12 could also receive the 300 to 600 KHZ band  plus 600 to 3800 KHz.
cd12a.jpg
This CD-12 is held by the C&E Museum in Kingston, Ontario. (Photo by Jerry Proc)

 
cd_12_front1.jpg
With handset stowed in the accessories lid. The original handset uses cotton covered cable. The lid and and interior of the case are sprayed with red lead primer. It is not known what other pieces were supplied in the accessories lid.
cd_12_front2a.jpg
A view of the front panel with the key in the stowed position.. 
cd_12_spares holder_a
This is the spares mounting bracket which is affixed to the upper right corner of the case interior. It can accommodate six spare tubes, two pilot lamps and two fuses. 
cd_12_nameplate.jpg
Nameplate. It reads: 
Type: CD-12 88416
Spec: 90133
Serial: 32
Date: 1940
All photos in this table by Moe Fretz 
cd12_interior1.jpg
CD12- top view
cd12_key_detail.jpg
The key in its unfolded position. It's made by  the Signal Electric Company, of Menominee, Michigan.
cd12_bottom_view.jpg
CD12 - Bottom view of chassis.
All photos in this table by Moe Fretz
FREQUENCY CONTROL

Using the Channel switch on the front panel, one of two crystal controlled frequencies could be selected . For operation under Master Oscillator control, the MO position is used. To adjust the MO to a new frequency,  the operator removes the dust cover from the front panel hole opening marked “MO”. Behind that hole is a variable capacitor. Using a small, flat bladed screwdriver, the oscillator stage is then retuned to a different frequency then the dust cover is reinstalled. A frequency meter will be needed to set the MO to the new desired frequency.
 

cd12_channel_sel_detail2.jpg
The selection of either of two crystals or the Master Oscillator is done with a three position rotary switch on the front panel. In this CD12 example, the Channel knob is missing. .
cd12_crystal_sockets.jpg
These are the chassis mounted crystal receptacles. 
/cd12_xtal3_assy.jpg
The MO coil shield bears the markings of 2128 and 2814 KHz. A pointer on the back of the front panel indicates which MO frequency range is in use. These frequencies are in the range of frequencies used on radio circuits of the Canadian Army, Pacific Command during WWII. 
cd12_xtal2_assy.jpg
Exterior view of the Master oscillator coil assembly.
cd12_mo_coil.jpg
Interior view of the master oscillator coil. 
All photos in this table by Moe Fretz 
 
DOCUMENTATION
The following FR12 documentation is available for download: Other than frequency control,  the FR12 schematic should be identical in all other respects with the FR12.
FR-12 Manual
FR-12 Schematic . This is a 36 inch x 24 inch schematic which has been scanned at full size and saved in both JPG and PDF formats. To print the schematic, simply download it then bring the file to your local graphics shop for printing. 
FR12 schematic in JPG format
FR12 schematic in PDF format.
CD-12 Overview Sheet

ERRATA

The nameplate on the dynamotor made by Robbins & Myers indicates an output voltage of 350 VDC at 225 ma.
 



Contributors and Credits:

1) Tom Brent <navyradiocom(at)gmail.com>
2) Moe Fretz <tubetester(at)gmail.com>
 

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Dec 23/16