02-07-2014, 12:25 PM
This morning I disconnected the antenna and hooked a scope lead to pin 2 of the 36 tube. I got a nice looking sine wave, that changed in frequency with tuning. I then, out of curiosity, connected the antenna lead again. It worked! It picked up all of the local stations well with 15 feet of magnet wire, and besides a little noise (shields aren't in yet) it sounded very good. What's more, even after all the coil surgery the dial is almost spot on.
I sent some Bing Crosby over the transmitter and wished I was old enough to drink some champagne
Then I went to disconnect the alligator lead from the 36 (just the lead, not the probe anymore) and it went totally dead, just like before. Ugh.. I reconnected it and it worked fine again. So, it seems like it needs 6 inches of wire on the top of the oscillator primary coil in order to oscillate. I'm totally at a loss as to why that would be.. Any ideas? The cathode bias is 680pf + 6k8 ohms.
Another concern, as I mentioned earlier the transformer has leaked a bit of wax. Under full load it's getting quite warm. Not hot, but warmer than I was expecting. The buzz went away when I tightened the bolts. That isn't normal, is it? B+ is pulling about 65ma, and all voltages are correct.
I sent some Bing Crosby over the transmitter and wished I was old enough to drink some champagne
Then I went to disconnect the alligator lead from the 36 (just the lead, not the probe anymore) and it went totally dead, just like before. Ugh.. I reconnected it and it worked fine again. So, it seems like it needs 6 inches of wire on the top of the oscillator primary coil in order to oscillate. I'm totally at a loss as to why that would be.. Any ideas? The cathode bias is 680pf + 6k8 ohms.
Another concern, as I mentioned earlier the transformer has leaked a bit of wax. Under full load it's getting quite warm. Not hot, but warmer than I was expecting. The buzz went away when I tightened the bolts. That isn't normal, is it? B+ is pulling about 65ma, and all voltages are correct.