10-05-2020, 12:00 PM
Thanks Russ. I used the rubber wire you suggested. I had to substitute orange for the yellow, as per your suggestion when using that wire with limited colors. Brown wound up being cloth covered as opposed to the rubber. Re-stuffing the AK capacitors is a bit of a pain. The cardboard tube is very fragile and getting the guts out had to be a little different procedure. Getting the speaker voice coil centered was also a bit of a pain. Tried one way first, which didn't work. The second attempt was a success.
Mike, yes I had a pile of rubber pieces under the chassis as I moved things around. This radio is a 708 but it actually follows the 808a schematic in several areas. Perhaps it is a later 708. All wire was changed out except for a couple of connections inside the IF cans. They were just reinsulated. AK put some kind of back stuff around all of the coils that encapsulated some of the short connections inside the cans.
After complete reassembly, the radio didn't work. B+ was only a few volts after the speaker field winding. Tracked an intermittent short to the RF/IF chassis. That was going to be a pain since it is not easily removable. Several wires connected to lower band switch connections would have to be unsoldered. I built up the rewire from the bottom of the switch to the top. The short turned out to be in one of the IF cans that I could remove by working through the slightly spread chassis. Turned out one strand of the wire I replaced for the plate connection up on the pad didn't go through the hole and was shorted against the ground plate of the IF adjustment pad. In about an hour I had it fixed and reassembled. Then the radio performed admirably, even with very questionable tubes. IF tuning was very close, as was RF. There are not a lot of controls for tuning. I got the oscillator to work all across the bands by replacing the oscillator grid capacitor with a larger value. Perhaps I will be able to go back to original value when I get a NOS 58 for the oscillator. I'll be contacting Bob Dobush today!
Now to solve some of the problems with the cabinet.
Mike, yes I had a pile of rubber pieces under the chassis as I moved things around. This radio is a 708 but it actually follows the 808a schematic in several areas. Perhaps it is a later 708. All wire was changed out except for a couple of connections inside the IF cans. They were just reinsulated. AK put some kind of back stuff around all of the coils that encapsulated some of the short connections inside the cans.
After complete reassembly, the radio didn't work. B+ was only a few volts after the speaker field winding. Tracked an intermittent short to the RF/IF chassis. That was going to be a pain since it is not easily removable. Several wires connected to lower band switch connections would have to be unsoldered. I built up the rewire from the bottom of the switch to the top. The short turned out to be in one of the IF cans that I could remove by working through the slightly spread chassis. Turned out one strand of the wire I replaced for the plate connection up on the pad didn't go through the hole and was shorted against the ground plate of the IF adjustment pad. In about an hour I had it fixed and reassembled. Then the radio performed admirably, even with very questionable tubes. IF tuning was very close, as was RF. There are not a lot of controls for tuning. I got the oscillator to work all across the bands by replacing the oscillator grid capacitor with a larger value. Perhaps I will be able to go back to original value when I get a NOS 58 for the oscillator. I'll be contacting Bob Dobush today!
Now to solve some of the problems with the cabinet.
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