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Author Topic: Amateur radio capabilities on the islands  (Read 1043 times)

Clarence Carlson

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Amateur radio capabilities on the islands
« on: May 21, 2017, 03:41:23 PM »

This research started after reading an older forum topic that speculated about ham operators being a potential source of radio signals on Amelia's radio frequencies during the search. I obtained a 1937 copy of The Radio Amateurs Handbook-The Standard Manual of Amateur Radio Communication and reviewed the April, May and June, 1937 issues of QST, a monthly publication from the American Radio Relay League. This is a subscribed service so links won't work. I also reviewed a letter from the TIGHAR website written by Yau Fai Lum, the radio operator on Howland Island during the search, Lum Letter and an oral history project which interviewed Victor BS Kim, the radio operator on Jarvis during the same period. Kim

Kim's interview is helpful in defining what equipment was available. He was chosen because he was a licensed amateur who already had equipment. Specifically he says: "Because the requirement was that I have equipment. That's why the want us amateur operators [on the expedition] because we have [our own] equipment". When asked about his method of operating he answered: "Yeah all Morse code. There’s no voice, voice is high class, costs a lot of money. You need extra equipment for that. Morse code is the simplest, cheapest”. And he says this: "I had to assemble it when I got there. Assemble it and get on the air the same day. See? On the receiver I had to buy a ready made one”. Since he specifically notes that his receiver is "ready made" he seems to be indicating that, like most amateur operators of the day, he built his own transmitter. In summary he refers to a "simple" morse (what is usually called a "CW") transmitter and purchased receiver. He also emphasized that radio time was limited, mostly based on battery power needs. “Only for that report I send in every night. That’s all. Outside of that I cannot talk to outside world…I cannot talk too long on the radio because I have a small battery and the generator it just lasts only for so many minutes. Thats all, and we have to recharge, you see, so we cannot do any talking". An aside: a lot of Morse operators refer to working other stations as "talking". I do it all the time and I pretty much use CW (Morse) exclusively.

Lum also had some specific recollections about his equipment. “I had a SW3 radio receiver and a home built with a 807 in the final" and "“My SW3 receiver only had a few coils in the ham bands and two that I wound to receive the Coast Guard frequency on 31 meters and a broadcast coil to recieve KGMB in Honolulu.” Here is echoing what Kim has said about a purchased receiver and simple home built equipment. Incidently the coils used in this receiver, made specifically for ham use, would not allow him to listen as low as 3105 kHz on his own equipment.

I will also note that all of the transmitter construction articles in both the 1937 Handbook and those issues of QST that were reviewed spoke only of crystal control. It was possible to build transmitters using other means of frequency control but it was not at all the norm and would have been inappropriate for portable/island use. It was difficult to achieve stability with such devices and the inexpensive receivers in use (such as the SW3) were not frequency calibrated to any great extent. It would be difficult to know with any certainty what frequency that one was using.

My summary would be that the radio equipment consisted of simple, low power crystal controlled transmitters and simple radio receivers, all operating in the code bands. Of course one caveat is that information for the equipment on Baker is, to me, unknown. The limited power resources available preclude much in the way of extraneous use. The notion that these transmitters could have, in any way, been used to transmit outside of the amateur bands, i.e. to interfere with radio traffic on 3105 kHz is so unlikely as to be impossible. I hope this information helps in understanding the "radio situation" on the islands.

 







Clarence Carlson
TIGHAR Member #3976D
 
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