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Recently acquired a Hallicrafters S40-B reciever that was DOA. We made a
few repairs and got it working (including some tube replacement and coil damage repair). We were a little alarmed when some of the voltages on the screens & plates were a lot higher than they should be. We then checked the schematic with actual resistor values and they came close in agreement with each other. Especially concerned about the higher voltages on the R.F. AMP tube (6SG7). Any suggestions? Also; has anyone looked into making a temporary mod to change the BFO into a Q Multiplier? The idea would be to add a .005, 500WVDC capacitor from the grid of V5 (6SC7) to the plate of V2 (6SA7), and inserting a 50K variable resistor between pin 6 and ground of V5 (6SG7). The 50K variable resistor would act as a gain control and affect the "Q" or bandwith. John KE0GG |
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