W.C. Tinus

• Circa 1937: Radio Development Department.
• 1962: Vice President of Bell Telephone Laboratories.
• "There's abundant contemporaneous literature, including schematics, of the 13C transmitter. The best is probably a sales bulletin published at the time by Western Electric called "A Three-Frequency Radio Transmitter for Airplanes" by W.C. Tinus, Radio Development Department."

1962 letter about Earhart's radio equipment

From Amelia My Courageous Sister by Carol Osborne (p. 278)

Note: "500 kc" in the text of the letter is "500 kHz" in contemporary terms.

I was the radio engineer who was responsible for the design and installation of her radio communications equipment [at the Newark Airport, New Jersey in February, 1937] and since there is apparently still some doubt as to what her equipment consisted of, perhaps I can clear up one or two points ...

I had been a radio operator aboard ship in my younger days and knew the importance of being able to communicate at 500 kc over the oceans. I persuaded Miss Earhart and Mr. Putnam on this point and modified a standard three-channel Western Electric equipment of the type then being used by the airlines to provide one channel at 500 kc and the other two at around 3000 and 6000 kc ...

A simple modification also enabled transmission to be made on CW or MCW, as well as voice, and a telegraph key was provided which could be plugged in, in addition to a microphone for voice communication. It was my thought that many ships throughout the world had 500 kc radio compasses and could probably better obtain bearings if the key were held down for an extended period while radiating modulated CW (MCW).

I was less successful in persuading Miss Earhart of the importance of having a qualified radio operator in her crew. I had only a short period one afternoon at Newark Airport to show her and captain Manning (of the United States Lines Sea Rescue fame) how to operate the equipment.

... I did not see her equipment during the period between the first and second starts, but had no reason at the time to believe it had been changed.

Several months after her disappearance we received a small package from Pan American Airways at Miami containing her telegraph key, cord and plug, which she had left in their hangar there. Without these items she could have communicated on 500 kc by voice and could have sent out a suitable signal for direction finding by simply holding the microphone button down for a time. The remainder of her equipment peculiar to the low frequency 500 kc channel probably weighted five or ten pounds, but apparently she did not leave it in Miami or it, too, would have been returned to us.

He ended:

... She was equipped for 500 kc communication originally and she did leave one item, her telegraph key, behind when she departed from Miami.