Wednesday, April 14, 2010
April 14, 2010 B-17 Radio Work
We had a very successful day at the Mighty Eighth Air Force Museum as we continued our work on the BC-348 receiver for the B-17 project. Carroll-WX4Y and Guy-K4GTM arrived at 2:00pm to get started with the days work. Over the last few weeks we have assessed the condition of the radio, tested the tubes, resisters, and capacitors, taken apart, serviced and tested the dynamotor which delivers the power to the radio, put the dynamotor back in and tested the the radio circuits, etc. Todays primary task was to replace one bad tube (the audio amplifier) and to align the various IF stages. Once we put the new tube in and powered things up, we connected a signal generator/spectrum analyzer to the antenna input and inputed a test tone on various frequencies to see if the receiver could hear it. Not only did the reciever hear the test tone, it was spot on frequency everywhere we tested it! Wow! Don't really need to do much of an alignment afterall. This is an outstanding radio for being 65 years old. Only thing to do next was to hook up an antenna and see if we could pick anything up. We moved the radio outside to be out of the metal building and away from all of the RF interference inside. We needed an antenna so I found a spool of wire that was perfect. We ran the long wire "antenna" out about 200 feet or so across the lawn and over a short tree to give it some elevation (10 feet off the ground at it's highest). We connected the wire to the antenna posts on the radio and wham, we were picking up a shortwave broadcast station on about 6.100 MHz! Was probably Radio Havana judging by the signal strength and frequency. We tuned around and picked up several other shortwave stations as well as some morse code and single sideband voice on one of the HAM bands. I can't tell you how excited Carroll and I were to the hear this thing come to life. We are so fortunate to be able to participate in this restoration project. Plenty more work to be done but this was a major accomplishment today.