Roots.
Returning to my roots, the days of vacuum tube electronics, and it's great fun. Had to excavate the ham shack to get my old tube-type receiver out. Then try to hoist the heavy thing up to my too small work bench today. Dust everywhere. Achoo!
The tubes lit up, no smoke so that was a good sign. Attached speaker and a short antenna wire and tuned around. Nothing, just hiss. Knew that wasn't right, if I picked up nothing else I should have heard all the garbage the digital electronics in the house pours out. Trouble shooting time.
Checked voltages several places, all seemed OK except for the HF oscillator tube. Grid voltage was supposed to be -3 or -4 volts, but this had -.389, plate and screen voltages were high too. So I hooked up the oscilloscope and probed a bit. No sign of oscillation. It's a simple circuit, but no oscillation on any band setting. Best I can figure the mica 15pF cap from the tank to the grid has open circuited. Going to be fun to replace that, it's buried in a nest of wires.
Also I need to use some tuner cleaner on the switches and controls, this thing is almost as old as I am. Looked for sources around me that might have it. Radio Shack is hopeless, but I found a surprising source - Oreilly Auto parts. Apparently there are many electrical switches and controls in cars today and they fail the same ways the old tube gear did.
All this activity is due to a Novice Rig Roundup taking place Feb 7-14 and I think I'd like to give it a go.
The tubes lit up, no smoke so that was a good sign. Attached speaker and a short antenna wire and tuned around. Nothing, just hiss. Knew that wasn't right, if I picked up nothing else I should have heard all the garbage the digital electronics in the house pours out. Trouble shooting time.
Checked voltages several places, all seemed OK except for the HF oscillator tube. Grid voltage was supposed to be -3 or -4 volts, but this had -.389, plate and screen voltages were high too. So I hooked up the oscilloscope and probed a bit. No sign of oscillation. It's a simple circuit, but no oscillation on any band setting. Best I can figure the mica 15pF cap from the tank to the grid has open circuited. Going to be fun to replace that, it's buried in a nest of wires.
Also I need to use some tuner cleaner on the switches and controls, this thing is almost as old as I am. Looked for sources around me that might have it. Radio Shack is hopeless, but I found a surprising source - Oreilly Auto parts. Apparently there are many electrical switches and controls in cars today and they fail the same ways the old tube gear did.
All this activity is due to a Novice Rig Roundup taking place Feb 7-14 and I think I'd like to give it a go.