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Monday, February 7, 2011

Amelia Earhart and Radio


Amelia Earhart   made a landing in Anderson South Carolina many years ago. A few days ago, I worked N6LYJ who lives there. I often look up the home towns of my radio contacts as a way of learning about their lives and appreciating their heritage. I like history.

She was a courageous person, and of course, the first female to attempt flying around the world. But it ended tragically,  and no one knows the exact location of the plane. It's never been found and assumed to be at the bottom of the ocean,  in water about three miles deep. Her last radio contact was just below the 80 meter band on the frequency of 3105 KHz, and as any ham knows, that means she was a short distance from her landing spot. The 50 watt transmitter had the call sign of KHAQQ and the aircraft was using a less than efficient V antenna. 

The high-frequency antenna installed aboard the Electra in March 1937 was a “Vee” type running from the tip of each of the twin vertical stabilizers to a mast atop the fuselage. The antenna was, therefore, a total of 46 feet, doubled back onto itself. It was then, already 15% longer than optimum; but since the radio equipment had been installed by Bell Labs, it can be fairly assumed that it was tuned properly at that time.
The length of 46 feet was greater than 1/8 wavelength at 3105 KHz (approximately 38 feet) and greater than 1/4 wavelength at 6210 KHz (again, approximately 38 feet; this relationship is due to the fact that 6210 KHz is the exact second harmonic of 3105 and the wavelength at the higher frequency is half that of the lower); or, a non-resonant length at either frequency.

Maybe some day, the aircraft will be found and raised back to the surface? It had the latest technology of its time. There was a "loop antenna" mounted above the cockpit which was used for "direction finding". Of course, all that means nothing when you run out of gas.....I can only imagine her final thoughts.

The "Lockheed Model 10E Electra" was Lockheeds first "all metal plane" with twin engines. Amelias plane had the famous "double tail".  It had a special Pratt-Whitney R-1340 engine that generated 600 hp.

1 comment:

Dick said...

Hello John. I've seen a few documentaries on her flight and disappearance. Some logical, some sci-fi. You know, space aliens. We will probably never be sure. 73 Dick