Amateur Repeaters

[K9STH]

Most amateur radio operators "assume" that repeaters came into use during the 1960s. However, I recently came across an article in the June 1945 issue of QST about VHF repeaters that were used in the old 2.5 meter band by amateur radio operators operating in the WERS (War Emergency Radio System) which was the primary way that amateur radio operators could operate during World War II.

Now most of the equipment used during that period of time consisted of free-running oscillator transmitters and regenerative receivers and one problem that existed was the fact that many stations were located in areas that had line of sight problems with working other stations in that particular WERS system. To get around this repeater stations were established to greatly extend the range of the 2.5 meter stations. These repeater stations used better quality superheterodyne receivers and crystal controlled transmitters. The receivers (repeater input) generally operated around 112.7 MHz and the transmitters operated around 114.6 MHz. The antennas used were verticals and they were usually separated by about 60 feet vertically (using the "cone of silence" isolation method).

The stations in the system desiring to be repeated would tune their transmitters to 112.7 MHz and the other stations would tune their receivers to 114.6 MHz. The audio was coupled from the receiver to the transmitter by a simple arrangement of the input would be plugged into the headphone jack of the receiver and then transformer coupled to the microphone jack on the transmitter. The receiver was placed about 10 feet away from the transmitter.

According to the article the range of the individual stations was increased substantially, especially for those stations that were located in lower elevations or those blocked by natural obstructions (i.e. hills).

Glen, K9STH

[KA4DPO]

That's interesting, I didn't know there was ever a ham band at 2.5 meters. It's not surprising that some clever hams figured out a way to repeat signals. I knew a lot of OTs who were hams during the war and most of them were involved in developing cutting edge communication technology.

[WB2WIK]

The local repeaters here started out on AM, not FM, in the 1950s.

Art Gentry W6MEP may have had the oldest 2m AM repeater in the country, not sure -- but this is claimed by some. He just passed on recently and there was a feature article about him in CQ a few years ago, while he was still with us.

Art is an ex-neighbor of mine and I was introduced to him shortly after moving to L.A. in 1988, when we were all a bit younger. He still had the original W6MEP/R 2m AM repeater in his garage at that time, and it was on the air since the mid-50s.

WB2WIK/6

[K9STH]

The answer to the question as to whether or not a modulated oscillator transmitter runs AM or FM is YES!

From the late 1920s until World War II the 5 meter band was 56 MHz to 60 MHz (the 10 meter band was 28 MHz to 30 MHz at the time and the 5 meter band was times 2 from the 10 meter band). Then in 1936 the 2.5 meter and the 1.25 meter bands were added. The 2.5 meter band was from 112 MHz to 118 MHz (the 10 meter band times 4) and the 1.25 meter band was from 224 MHz to 230 MHz (the 10 meter band times 8). The next highest frequency band was 400.0 MHz to 401.0 MHz. When the United States entered World War II all amateur radio operations had to cease. Then in June 1942 the War Emergency Radio Service was established utilizing frequencies between 112.0 MHz and 116.0 MHz. The range from 112.0 MHz to 115.2 MHz were for "general" Civil Defense use and the frequencies between 115.2 MHz and 116.0 MHz were reserved for "State Guard" (basically non-federalized National Guard units - primarily older men) and for "CAP" (Civil Air Patrol units).

Although modulated free-running oscillator transmitters and regenerative receivers were the "norm" on the old 2.5 meter band and on the 1.25 meter band, crystal controlled transmitters and superheterodyne receivers were being built for both bands by amateur radio operators by the mid to late 1930s. Of course the military had abandoned free-running oscillator transmitters in favor of crystal controlled transmitters by 1940 some of the units still did use regenerative receivers all the way through World War II. However, superheterodyne receivers became the "norm" for all frequency ranges except for VLF receivers (below 200 kHz) where regenerative receivers were still very common even in the 1950s and well into the 1960s.

Glen, K9STH

[K0RGR]

That's an interesting story, Glenn.

My dad used to tell about how he worked 10 meters back in the mid-30's. He didn't own a transmitter for 10, but he did have a receiver. He was a Class B licensee then, which meant he was restricted to 160 and 10 meters for 'phone.

Now, he had a friend a few miles away who did have a 10 meter transmitter. His buddy wasn't home in the daytime, so to help his other Class B friends in town, he'd leave his 160 meter receiver parked on a given frequency. Then, he put his 10 meter mike in front of the loudspeaker on the 160 receiver. The local boys would get on 160 and be retransmitted on 10 meters. The guy would just leave the 10 meter rig keyed up all day! The Class B guys would call CQ on 10 this way, and listen on their own home rigs for answers, which would usually not be on their own frequency anyway, so they could effectively work crossband full-duplex.

Of course, such goings-on would get you a lot of pink slips from FCC today, but back then, apparently nobody cared.