Restoring Firestone 4-A-20

[Reece]

The rubber-insulated wires to the primary of the output transformer were crumbling, so I replaced them with same-colored new wires right at the transformer, with the soldered joints covered with heat-shrink tubing, and the wires bundled out of the way of the 35Z5 with a couple of mini wire ties. Note that this has negative feedback off the voice coil heading back to G2 of the first audio tube. This tends to cancel out some distortion, a nice touch and not expected in such a radio. Also note the shorty 'lytic cap hiding down inside the cardboard tube.

All the caps in, line cord ready, time to plug in the tubes and turn it on. Nothing! Neither dial light nor tubes light up. All the tubes were previously tested good. Suspect bad switch. Get the voltmeter. Nope, line voltage gets through the switch, but it doesn't get to where the line from the radio side of the switch goes, which is to the can of the electrolytic. That wire fastens to a can lug with several other wires and the solder didn't get down to it. I retouched with the iron and reflowed the solder and gave it another try. She plays, and not bad! I got BC stations across the dial, and with a short antenna, a station and some other typical SW noise on the other band, all in the middle of the afternoon. I touched up the I.F's and the RF and ANT sections of the tuning cap, and this turns out to be a hot little radio with that RF stage. Up and down the dial it's full of very listenable signals.