![]() I have a few power supply/audio amp chassis from car radios where the tuner and volume control is mounted in or under the dash but the supply, amp and speaker are mounted on the firewall. There is one for £2000 in England, but I don't suppose there are many Spitfires left needing a genuine war radio. I even have a supply for a Spitfire, but as I see two more coming up in an auction, there goes the value for that up in the air. ![]() I have collected many rotary power supplies and vibrators over the years. I suppose my Dad's radio room alive with the buzz of battery vibrators is the cause of my obsession with the things. I could make up a battery bank of sorts but with infrequent use, this would be waste of money and there is always the risk of them leaking and therefore corroding everything. Next for my attention was a more permanent power supply, batteries not being available any-more. Some of you may have noticed the calibration book was not for this unit, believe it or not, the calibration sequences are spot on! Putting it back in the case and powering up, it works well. I manufactured an aerial connection from a. It was a 12 SJ 7 for a 12 volt system, swapping it for 6 SJ 7 brought a hot valve and a good signal. I left the valves on without the B+ while I had dinner when I got back I sensed the output valve was barely warm compared to the other metal valve. Resolder and more testing, Bingo, a signal although it seemed weak. This resistor and some others are not originals. There is re-soldering on the output valve's socket, the cathode resistor had come adrift. Some testing with a shortwave radio and a Digital frequency counter, I found - 'nothing' Next was the B+, I used a dropping resistor connected to a mantle set as the power source. The leads soon started to give off “The Smoke”Īfter some poking around I found pins 2 and 7 of one of the valves were bridged together, snipping that allowed the valves to warm up. Next came the testing of the unit itself, the headphones must be plugged in to 'Switch on' the unit.Īrmed with a circuit I checked the filament circuit connections and applied 6 volts from a truck battery.
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