The Experimental Radio Project
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The
schematic. Click on the picture for larger version.
| Not the greatest feat of engineering in the world,
but it works well for such a simple radio, and even picks up some
shortwave at night! A technician friend pointed out that it appears the
RF Gain control can short out the battery. Not really, there is a 1K
resistor ahead of the
control. With the control set to 0 ohms I did not see the battery voltage drop
at all. With the volume control set to minimum, the set
draws
6 mA of current. Setting the RF gain control to 0 ohms causes the
current draw to increase to 12 mA. At full volume the set draws
50+ milliamps. Since the listener would never turn the RF Gain control
to 0, this seemed acceptable. |
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So what happened to the cool TANDEM
TUNER? |
I still have the coils
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I removed the TANDEM TUNER before I got the RF amp working.
In the future I'll wire it back up and see how it works.
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Now you may ask yourself "Why
would anybody want to turn all those knobs to tune in a radio
station?"
Well first of all, it's fun! Secondly, radios from the
early 1920's actually had a lot of knobs.
This factory made one has
six. (and no speaker!) |
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This American Marconi model 106 from 1918 has seven knobs and two adjustable crystal
detectors, just to TUNE the radio.
There is no amplification of any kind. This one is worth over
$20,000. FYI - The American Marconi Company was controlled
by the British Marconi Company. In the interest of national
security, a new
U.S. company was formed in 1919 to buy out the British
interests. Almost all of the financial, capital, technical and human
assets
were transferred from American Marconi Company to the newly
formed company, the Radio Corporation of America. (RCA). |
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| This concludes our broadcasting day. |
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