Micamold XTR-1 Transmitter

02/12/04

This is the Micamold XTR-1 transmitter manufactured in 1948 by the MICAMOLD RADIO CORPORATION of Brooklyn, New York.  Micamold was a famous capacitor manufacturer and made a brief, a very brief, entry into the amateur radio transmitter business with this transmitter.  It was introduced in 1948 at a cost of $34 + tubes but by 1949 the radio suppliers were heavily discounting the transmitter by offering it for $19.  I believe it couldn't complete with other low cost and better built and better looking transmitters like the WRL Globe Trotter for $69.  

The XTR-1 is a three tube 25 watt transmitter that covers the amateur frequencies of 20 meters, 40 meters, and 80 meters.   For a low cost transmitter, the XTR-1 still features some higher end features like a really nice looking meter, single knob frequency band switching rather than separate plug in coils, a built in power supply, and a buffered oscillator to minimize chirp.  It is typical of the lower cost designs of the 1940's with an oscillator stage, separate 6L6 amplifer stage, internal power supply.

The front panel features, left to right, an ON/OFF toggle switch, cw key jack, Plate Power toggle switch, frequency band switch, Plate tuning, Antenna load tuning.  The antenna jacks are screw terminal and are mounted on the top of the chassis, rear right corner.  The crystal socket is located on the top of the chassis, front left, using an octal tube socket.  The bottom of the chassis is covered.  The transmitter uses a 6AG7 tube as the oscillator and a 6L6 or 1614 tube as the amplifier. A type 83 is used for the high voltage rectifier.  The XTR-1 bares a remarkable resemblance to the Ameco AC-1, almost like the AC-1's big brother. The circuit is similar, though set up for the higher power output, similar chassis style, similar colors and silkscreen, knobs, etc.

If you have a Micamold XTR-1, I would appreciate hearing from you. I am aware of only 5  others in the BA world.  One of them was in the CQ Classics Calendar in 1998.  I wrote an article on the Micamold XTR-1 which was published in QST March 2004, as a guest author in John Dilks Old Radio Column.

 

Click on the thumbnail photo to bring up a large picture. Photo of my XTR-1 in the radio room. 

Click on the thumbnail photo to bring up a large picture. Photo of you-know-who at the XTR-1 / Hallicrafters S40 operating position.  

Click on the thumbnail photo to bring up a large picture. Below the chassis photo.
Click on the thumbnail photo to bring up a large picture. Photo of the rear of the radio. 
Click on the thumbnail photo to bring up a large picture. Closeup of Micamold meter. 
Click on the thumbnail photo to bring up a large picture. Closeup of front panel so you can read the silkscreen lettering. 
Click on the thumbnail photo to bring up a large picture. Closeup of ceramic terminals on rear panel.  Click on thumbnail to bring up full size photo.
Micamold Manual Page 1, Schematic and Parts List

Micamold Manual Page 2

Micamold Manual Page 3

Micamold Manual Page 4

Micamold Schematic Diagram

Micamold Advertisement

Giles Crabtree's 1948 Micamold XTR-1 and Hallicrafters S40 station
Giles Crabtree's 1948 Micamold & Hallicrafters S40B Story Part 1
Giles Crabtree's Micamold & Hallicrafters S40B Story Part 2
Giles Crabtree's First QSL Cards using the Micamold
 

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Copyright 2004 Scott Freeberg

This site was last updated 02/12/04