RAN Technology

The Foxhole Radio


Vintage Radio 1 Comments 03/08/2019 

aka "Razor Blade and Safety Pin Radio"...from the Boy's Fun Book

Posted By: Robert Nickels (ranickels)

 

When I was a kid, my dad gave me a thin hardcover book called "Boys Fun Book - Things to Make and Do".   It was printed during WWII on very thin paper as a wartime conservation measure, but was chock-full of interesting projects, ranging from hobbies and magic tricks to sports, puzzles, camping...and the chapter I was drawn to:  "Unusual Radios You Can Build Yourself".

Foremost among those featured was a one page article titled "Razor Blade and Safety Pin Radio" which appealed to me because it didn't require any fancy electronic parts lile tubes which were beyond my skill level at age 8, but only required a coil of wire, some odd bits of junk, and headphones, which I did have.   And it came with a very cool story that both the book and Wikipedia tells us probably originated at the Anzio beachhead in 1944 (perhaps because one was the source for the other?)

All of which mattered not to me, I just wanted to build it!    So with my dad's help, I did and while we didn't have any "blue" razor blades handy, I found that the regular single-edged kind worked fine with the adaptation described, by carefully attaching a short length of pencil lead to the cat-whisker.   I now know that the junction between the lead and steel blade created a crude rectifier.   (Most hams learn fairly quickly that almost any dissimilar metal joint will act as a rectifier!)

But it worked!    At least in the sense of being able to hear the local AM station, which is all any of my crystal sets ever really did from my small town in central Nebraska.   My parents, relatives and friends were always amazed that such a simple gizmo could actually work as a radio!

And it didn't take long for me to realize this was Science Class gold!   I leveraged the Foxhole Radio and accompanying story of innovative soldiers from WWII, which was still a big part of late 50's American cultural awareness as much as I could - I remember at least one "A" grade for a class presentation about it in lieu of writing a report or something boring.

It will be a sad day if AM broadcasting is ever replaced with digital noise, if for no other reason than it would mark the end of over 100 years of reception by the simplest radios of all.

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  •  BRADLEY STONE (NB9M)

    When I was a kid, Dad told me stories about soldiers fabricating radios out of used razor blades during the war. I think I tried to do it, but never heard anything...

    Reply |  0 Replies

    Posted 03/12/2019  

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Category: Technical
 There is a lot of misunderstanding about how a Class E amplifier works.    Including my own ;-)   As the result of studying the literature and experimenting, I thought I'd share what I have learned.Below is an example of a test amplifier I used to optimize my 2 watt wspr transmitter boards.   It can be visualized as two circuits - the amplifier itself a...  READ MORE
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- Robert Nickels (ranickels),  05/14/2020 
   The HW-16 had to be pushed aside while waiting for parts, creating an opening just big enough for the homebrew receiver I got recently via eBay for $18.50 - plus 2X that to ship it here.   I like saving and restoring old homebrew gear just out of respect for the amount of time and effort our forefathers put into making things from scratch, and this receiver intrigued me, as the IF transf...  READ MORE
- Robert Nickels (ranickels),  04/28/2020 
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- Robert Nickels (ranickels),  04/22/2020 
  

Wireless on a Train

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Category: Historic
WHEN Frederick Wally stepped out of a little cubby-hole in one corner of the forward day coach on the Lackawanna Limited, west-bound, as it neared North Scranton, Pennsylvania, Tuesday, November 25, 1913, and pinned a sheet of paper on the wall, the passengers in the front seats, who had been casually wondering what caused the strange, crackling sounds that had been coming from the cubby-hole, pri...  READ MORE
- Robert Nickels (ranickels),  04/14/2020 
    The  Dentron MLX-MINII thought it would be cool to use the Dentron MLX-MINI on the Saturday Vintage Sideband Net but it's a little marginal since the rule is "no tubes, go home!".   However hybrid rigs are allowed, and Special Dispensation is given for rigs with Red LEDs.    So I thought the MLX was double-qualifed - even more so after I realized t...  READ MORE
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