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| May 2000
1-A model 453 has a note on circuit diagram for connection of heater, so 1-A has 12V heater voltage for calibrator 2-A, 2-B, 2-C have 6V heater voltage for calibrator, and in fact for 2-C the only purpose for 6V heater is the 3* #47 lamps, the calibrator and 2-CN. The 2-C was purchased in 1967, serial number 0653, circuit diagram 1001660007. The reason I sold it to LA6VM after 1 month was that it does not have true passband tuner, like 2-B, but only passband switch ganged with mode selector for AM/SSB, and AUX XTAL Socket for operation on 28.6-29.7MHz. It should be noted that 3rd mixer injections shifts between 405/505kHz for USB/LSB mode selection. The circuit diagram only shows SSB/AM selectivity, but it is achieved different from 2-A. Next stage is to draw the development of passband tuners for the different receivers. see attached files.
Click to enlarge Pics jan-martin Noeding <la8ak@online.no> 73 |
