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I have switched gears! 2002 has been a banner building
year for yours truly. So far, 7 crystal sets and 3 tube sets. My next homebrew
project will be a 2 tube broadcast receiver using types 32 and 34 tubes.
But, here is my restoration story. Earlier this year my friend Jack Aber, K2IZA
learned of my new found hobby of old radio building. At the time I was doing
only crystal sets. But Jack gave me this old homebrew tube set.
I was very thankful as I never owned such an old radio. However old tube
sets were unknown to me and I was involved in building the crystal sets.
I left the radio in the living room, showing it to my guests. It was not
cleaned up and the correct tube was missing. So it sat for 3 months before
I had any idea what to do with this radio. I found an 01A tube on Ebay.
I thought that this would be a good tube to use as there are a lot of them
around, and it was entirely possible that an 01A was originally in this
set. After I received the tube, I plugged it in, hooked up the voltages
and fired it up. It didn't work very well, but it received a station!
Wonderful!
At that point, I decided that I would do a full restoration. This will
include taking the radio apart, cleaning all the parts, obtaining new
hardware where needed and sanding and finishing the cabinet.
I have no
information about this set except for the circuitry. But I believe that this
set was probably built between 1922 and maybe 1930. The circuit was very
strange indeed. (I will provide it later). This radio is the regenerative
style.
The parts consist of a tube (01A type), a bayonet tube socket. A grid leak
resistor and socket, a 250mmfd fixed capacitor, a filament voltage rheostat,
a tuning capacitor and a variometer. A variometer consists of an outside
coil and a rotatable coil. The coils are connected in series and the
resulting inductance will be the inside coil plus the outside coil to
the inside coil minus the outside coil. The "mutual inductance" number
(less than unity) also figures into this. I built a variocoil which is
a cousin to the variometer.
Please follow me through this project. The next page shows the cabinet
disassembled and the parts strung out.
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