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Published on Aug 15, 2009
Here it is...THE BC-610-E, serial number 1175. The earlier models of this were used at Pearl Harbor, and later, in the Pacific during the Battle of Midway. This unit was used in the late part of the war and then sent to the USMC service depot in San Francisco in 1950 for an overhaul and moisture and fungus proofing coating in preparation for future use in the Pacific...but ended up at the former US army base at Fort McClellan in Alabama as a training transmitter. This classic art deco design transmitter has survived 68 years! Fully restored by me in 2008.
Power input = 2,500 V x 0.25 A = 625 watts d.c. Plate efficiency = 71%. RF carrier power output = 445 watts. Modulating impedance = 10,000 ohms. Modulation transformer reflected primary impedance = 5000-0-5000 ohms (or 20,000 ohms plate-plate)
Maximum sinewave output of modulator using 2,500 V d.c. supply, 0.28A peak modulator current = 485 watts audio output at secondary of modulation transformer.
625/2 = 312 watts audio required for 100% modulation, so 485 watts represents +125% voltage modulation level.
Yes, I am running the transmitter plate dissipations a bit hot, like a hot rod car for all out drag racing, but then that is what these things are built for!
Like restorers of WWII military aircraft, I'd love to hear from any other BC-610 owners out there...make your videos of your transmitters and share their history on youtube!