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Richard Arnold, AF8X
af8x@comcast.net
December 18, 2007
From spies to smoke jumpers, miniaturized radios do their part.
As a youngster, my fascination with Morse code quite naturally led me to an interest in spy stories where the characters used clandestine radio transmissions from hidden or disguised transmitters. I was surprised to learn that the majority of these rigs had pretty low-output power levels. Also, I learned that "spy radio" was not something new during WWII. In fact in 1917, a German national named Hans Wax, living in New York, was arrested as a German spy. The police discovered a wireless telegraph receiver capable of receiving Morse transmissions from Germany, hidden in a box disguised as another device.
There are many movies showing radio operations during WW II, some by the underground resistance groups, some showing use by secret agents, for example The Eye of The Needle. During this period, many specialized radios were developed. Their design depended on the tactical situation in which they were to be used.
Different Jobs ─ Different Radios
An early World War II British design was the Mark XV regenerative receiver and 15 W transmitter. After several upgrades the Type III MK II, better known as the "Suit Case Radio" was used until the end of the war in 1945. Output was about 30 W and almost all of these type radios used simple wire antennas.
The British also created some very small portable units that were distributed to the resistance groups in occupied France. Operation of these secret stations was inherently dangerous for the operators. The enemy mobile direction finding units would locate the area of the transmissions and the operator and station had to be transported or disguised very quickly. Therefore the radios had to be very small and portable.
The Australian "Coast Watchers", on the other hand, were equipped with gear commercially manufactured by the Australian company Amalgamated Wireless. The units comprised of separate transmitters and receivers in specially designed cases with rounded corners and strong clip-on covers to enable them to survive, the sometimes rough, trips through the jungles. Power was provided by battery, a pedal-generator, or ac mains. One of the later model 3BZ transmitters covered 10 to 2.5 MHz with a power output of 12 W on CW and 15 W on phone. The usual antenna was a quarter-wave Marconi for fewer than 100 mile communications and a half-wave Hertz single wire for distances up to 500 miles.
Most of these radios, by today's standards, were primitive and not as user friendly as the rigs available today. Even so, they got the job done and the stories about them make interesting reading. Some of them can still be seen in museums and in private collections.
The popularity of these old agent radios is evidenced by the prevalence of the WWII Paraset replicas being built by Amateur operators. The Paraset was a small, low-power CW transceiver supplied to the resistance groups in France, Belgium and the Netherlands during WW II. I was thrilled to have made contact with W0RW using his homebrewed Paraset replica from Colorado. The signal was very good considering the distance between Colorado and Michigan confirms the achievement of low power communication using these primitive rigs.
Smoke Jumper Mobile
While surfing the Internet and looking through the radio museums, I stumbled on this picture with the caption, “U.S. Forest Service key c. 1930s. Used by smoke jumpers with 5 W backpack radio.”
This was a facet of radio history I had never heard of. Sure, I have seen movies with firefighters using handheld radios, but this picture indicates radio communication in the 1930s used CW to keep in contact with fire watchtowers or control points several miles away. The firefighters were able to request help or more equipment and give updates on their progress. The portable backpack rig was described as the model 8, a low-power CW, battery powered transceiver, considered small and lightweight in those days. (see picture) Antennas consisted of wires strung up in the trees.
I continued searching the Internet looking for more information, but there is very little available. I was interested in the rigs and their operators, but can only assume that they developed from the military use of wireless during WW I.
* Not all spy radios qualified by today's standard of 5 W or less.
Richard Arnold, AF8X, enlisted in the Air Force right out of high school and spent four years as a Medical Equipment Repairman. After his discharge in 1955, he trained as an electrician and worked in the Detroit area till his retirement in 1984. Since then he has been pursuing his interest in flying and radio. He enjoys riding his bicycle to local parks near his home in Clinton Township, Michigan and operating with his Elecraft K1 and KX-1. He also likes to play golf and is developing an interest in writing.
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