Previously a panorama was traced about the scientific
and technological evolution of the Electronics in the
military communication. However, considering this advanced
technological context an interesting aspect is distinguished,
not only for its simplicity, ingenuity, but, also, for
its versatility that only the Radio as media could offer,
in the case the FOX HOLE RADIO.
At the first glance, one could be thought it is related
with a sophisticated device developed in the most secret
laboratories of the Armed Forces. However, in the reality
it is nothing more than a simple crystal receiver.
This type of radioset uses a piece of crystal - the
galena or lead sulphide - as a radio waves detector.
As aforementioned in early chapters the crystal receiver
detects the radio waves by the principle of rectification,
discovered in 1903, by the American researcher Greenleaf
In this way, the FOXHOLE RADIO is peculiar as in the
place of a piece of galena crystal it used a simple
razor blade. Yes, that's right, just a simple razor
blade! Nowadays, replaced by the one-way razor pack.
Due to the structural characteristics of the steel used
in the manufacture of the original razor blade, it could
behave as a rectifier - i.e. allowing the passage of
AC oscillations in just one direction - and so it was
capable to detect the radio waves.
Basically, the FOXHOLE RADIO comprises a single razor
blade, a small contact pin made of pencil lead actuating
as the famous cat's whisker and a high impedance earphone.
In the battlefield the GIs of the allied armies looking
for news about the war or even the far way home, invented
this type of receiver using simple parts, as a razor
blade. The most sophisticade one in the case of the
earphone, it was taken from the radio communication
In spite of its simplicity, through this kind of radioset
Armed Forces radio stations up to twenty -five miles
away could be heard, using a fairly good antenna and
In case of interest, this fantastic receiver can be
constructed easily using simple materials found everywhere
The most difficult part is the earphone. However, with
a certain dose of patience, by looking in flea markets,
junk yard or even at some aunt's Mary attics, one can
get it from an old telephone. Old telephones use high
impeadance earphones and so they are suitable for such
You should try it! It is just a fantastic experience
for us accustomed to high-speed computers and the INTERNET
one can feel the importance of this simple kind of radio
for the soldiers far way home, anxious for news about
the war and home. (a)