The Experimental Radio Project
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
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.
So what happened to the cool TANDEM
I still have the coils |
I tore out the TANDEM TUNER before I got
the RF amp working. In the future I'll wire it back up with the solderless breadboard and see how it works.
| Now you may ask yourself "Why
would anybody want to turn all those knobs to tune in a radio
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!)
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
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
were transferred from American Marconi Company to the newly
formed company, the Radio Corporation of America. (RCA).
|Parts and kits:|
interested in this hobby, try:
- a whole site dedicated to small sets and parts, magnet wire, etc.
- kits and parts.
Resistor and capacitor kits can be found
and almost anything can be found on
Stay away from the Chinese knobs on ebay, they are inexpensive, but they
don't fit anything.
|This concludes our broadcasting day.|