TO BE LOUD – GET HIGH!
From the time I saw the first radio I wanted to know how they
worked. I was fortunate enough to find a good used book that did a good
job of explaining just about everything that was known about radios at
that time. The section on detectors told how a galena crystal separated
the radio signal from the carrier frequency and how the slider on a coil
could select a radio station. The same thing could be done with a coil
and a tuning condenser. A tuning condenser was a set of aluminum plates
that meshed with another set and varied the capacity between the two
sets. When connected across a coil of wire this made the coil/condenser
unit select different radio stations, depending on how much of one set
of the plates was meshed with the other set. The commercial radios had
three or four of these coil/condenser units with tube amplifiers between
them. All of the units had to be tuned to the same frequency by
adjusting the knobs on the front panel.
My interest turned to a crystal radio that used no batteries. The
tuner could be either a coil with a slider that selected a different
number of windings or a coil and variable condenser like the commercial
radios used. The old radios were plentiful and not in use so I soon
collected several for my experimental project. The crystal radio
didn’t have any power for a speaker so it was necessary to use a
headset or an old telephone receiver to hear the programs. Since I
didn’t have a headset and old telephone receivers were plentiful, I
used an old telephone receiver. The crystal radio was very simple. It
only had a coil and tuning condenser from an old radio, a tiny
condenser, also from the old radio, and the receiver. The important
thing was a good antenna. The antenna should be as high as possible for
good reception. The ideal length of the antenna wire was about two to
three hundred feet.
The crystal radio was quickly assembled. The total cost had been
the 25 cents for the crystal and holder. We connected the antenna and a
good ground and prepared to test the receiver. Ordinarily a crystal
receiver didn’t perform very well in the day but picked up several
stations at night. I held the receiver to my ear, meshed the tuning
condenser about halfway with the knob and probed on the crystal with the
“cat whisker”. It was
about one o’clock and the Chuck Wagon Gang from
With a little more study and engineering we added another tuned circuit and this helped considerably with station separation but cut down the volume some. It was good enough for two country boys.
Eventually we had several headsets and this enabled listening for several family members at the same time. We used the crystal set for about three years before radios were improved and batteries were affordable for country folks.
There has been a revival in the interest in crystal radios. There are many clubs and individuals building and experimenting with the radios that operate without power. The radio waves transmitted by the station provide all the power that is needed. There have been many improvements. The tuning coils now use ferrite cores that slide in and out of the coil to find different stations and the galena crystal has been replaced by high frequency silicon diodes that do not have to be probed with a sharp “cat whisker” to find the best spot for detecting a signal.
The high, long antenna was the secret that made our crystal set useable. Did we have fun building the crystal set and putting up the tallest antenna in the county? We sure did. Perhaps you ought to build one some day!
Everyone needs to have a little fun!