In the 1950's I was an operator of an AN/GRC-26 portable radio system in the U.S. Army. It ran phone (A.M.), digital (RTTY) and CW. The transmitter was a BC-610 which I believe was the successor of the HT-4 transmitter shown here.
The whole "portable" system was built into a hut that was mounted on 2-1/2 ton 10-wheel truck pulling a 1-ton motor generator on a trailer behind it. Had some real adventures climbing mountains off-road with that rig, but it had two huge advantages over today's "pocket-portables" - we could stay inside the hut out of the weather and it had a coffee pot. The Ham activity on the film has one huge missing bit: no heterodynes! When two A.M. stations are close enough to the same frequency to hear the audio, you also hear a loud tone whose frequency is the difference between the two carrier frequencies. Often on a crowded band like 20 meters you might hear three or four of these heterodynes blasting away on top of the audio of the station you are trying to hear. Unlike today's rigs, most "phone" receivers of the 40's and 50's had a 6 to 10 kHz bandwidth! In the early days of SSB, that lack of heterodynes was the most common reason cited by Hams for leaving AM for SSB. Power efficiency, denser band occupation, and the like were secondary reasons, at best. Ron AC7AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
