Back to the radio...
The short wave band (Band 4) didn't work very well.
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The forty meter shortwave
band is at the top of the green coil, six turns of wire. It
works great for broadcasts but I had to
turn the volume all the way up to hear any "hams". A coil of
ten turns of 24 gauge wire, space wound on a 1 1/4 inch coil
form,
covers the same band. When dropped inside the main coil. The
difference in the radio's volume is dramatic and it also
seemed to make the Morse code more stable. (less warbling.)
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The little coil now lives
inside the big coil and is the new "Band 4".
I hooked it up backwards the first time so I used red and black wire to
prevent me from getting the wires mixed up.
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After using the radio for awhile, it was found
that the control above, which coupled the RF amp to the tuning coil,
did very little. In series with the 365 pF variable capacitor was a
47pF fixed capacitor, which gave a total of 42pF with the plates
fully meshed. It was replaced with a 33pF fixed capacitor, which
costs about 20 cents versus the variable cap which costs about 20
dollars! |
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How well does this thing work? I give it a score of
"pretty good" but you sometimes have to work at it because it's a
regen set. Strong local stations come blasting in like it's a superheterodyne.
Tuning in a weak station
takes some effort, but that's where the fun comes in. There
are two "flamethrowers" at 1060 and 1440. We listen to 990,
1180 and 1210. The flamethrowers tend to swamp the dial but you can
eliminate them completely with a little effort.
After hearing how well the little coil works on Band 4, I may make a separate coil for each
band in the future.
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Making the paper face plate. It
had to fit on a single piece of printer paper. |
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The schematic.
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The audio section is a standard
LM386 configuration. Notice this is set to "Gain = 200." The gain is
set with the 10 uF capacitor across pins 1 and 8.
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Here's my temporary card table "workshop"
in the kitchen. |
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William Shockley, John Bardeen,
Mike Simpson and Walter Brattain discuss the principles of the basic
circuit while listening to "Coast To Coast AM" with George
Noory.
They are discussing time travel in this episode of the program.
That's amazing! as George would say. |
