[Boatanchors] Re Fox Hole Radio

[Al Klase]

"Duane Fischer, W8DBF" wrote:
> 
> 
> I have heard the stories of WW2 soldiers making a radio from a razor blade, some
> wire, a lead pencil and a safety pin. My question: precisely how?
> 
I became aware of this concept from the Pop 'Tronics article
John mentioned, probably in the early '60's.  It showed the
simplest possible crystal set, just a detector in parallel
with the headset and connected to the antenna and ground. 
Detector was a blue razor blade in contact with a pencil
lead lashed to the sharp end of a saftey pin.  Mounted on a
block with one wood screw through the middle of the blade
and the other through the bent-over eye of the pin. You
might need to scrape part way through the blueing.  Recent
speculation is that the blue coating is a selenium compound.
(See selenium rectifier.)

Glen's right.  The important thing is the headphone.  You
can improvise everything else.

1970 found the kid at Cam Rahn Bay.  After noting that we
could hear the AFRTS AM station, abount a mile away in Dong
Ba Thin, on field phones attached to unterminated lines
lying on the ground, I decide that the fox-hole radio
tradition needed to be upheld.  Sure enough it worked using
a purloined field-phone receiver element a modest antenna
and a ground wire tucked under my bunk leg.  Keep in mind
that the field strength was pretty high.

Other factors:  A variable loading coil (slider) in series
with the antenna lead is a worth-while improvement. 
Standard headsets in early WWII were high impedance and work
better than the later lo-Z "ANB" and field-phone elements. 
In the 1940's "everyone" knew how to build radios.  If you
were in the right place you might find galena or fools gold
to make a better detector.

My two cents,
Al

-- 
Al Klase - N3FRQ
skywaves@bw.webex.net
Flemington, NJ 08822
Web Page:  http://www.webex.net/~skywaves/home.htm