Frequency range:  . The tuning of this receiver is unusually complicated. One would have to post all of the pages from the Practical Wireless Handbook so that the reader would understand what the author was talking about. At the bottom of page 147 in Practical Wreless, the author said that the 107A could  be tuned in excess of 3000 meters. This can be  can only be summarized by saying that on " Tune" , it could be tuned from 300 meters to 1000 meters, and on "Standby", it could be tuned from 300 meters to excess of 3000 meters.

Vintage: 1917
Comment: Originally , this radio was marketed as a Fleming Valve Tuner by  American Marconi. In a conversion process, a carborundom crystal was provided which could plug directly into the Fleming valve socket , The LF tuning range was also extended from 1650 to 2500 meters. A spare socket on the face of the unit was used for the storage of a spare valve.

The type 'I'  antenna switch was also used with the 107A receiver.

The Fleming Valve tuner/detector was the basis on which the type 107A device was created. It appears odd that t American Marconi assigned type 107A instead of 107 once the device was converted. The conversion entailed the replacement of the Fleming valve with a crystal detector and  expanding wavelength coverage to 2,500 meters. Radiomuseum.org)

107A tuner/detector, The carnorundum crystal holder csn be clearly seen in this view. (Radiomuseum.org)

107A controls. Click on image to enlarge.  (Via Practical Wireless)

Fleming Valve receiver schematic before conversion to type 107A. Click on image to enlarge. .(Via Practical Wireless)

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(Via Practical Wireless) .

(Type ' I ' antenna  switch.  (Via Practical Wireless)

 

	Figure 165B. This is the circuit configuration for receiving short wave. It was called "TUNE"  (mode) back then. Click on image to improve clarity.
	Figure 165A. This is the circuit configuration for receiving long wave. It was called  "STANDBY" ( mode) back then. Click on image to improve clarity.

 Credits and References:

1) Radiomuseum.org/r/marconiusa_107a.html
2) Lewis Bodkin 05bodkin555(at)gmail.com
 
 

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Mar 24/21