[Milsurplus] Foxhole Radio - conclusion

[Al Klase]

John,

That's consistent with with my observations.  However, a lightening 
strike in the next county will send you searching for another spot on 
the galena.  Commercial operations generally relied on more reliable 
detectors, like carborundum (with bias), silicon, and various Perikon 
pairs, at the expense of sensitivity.

Al

On 8/6/2012 2:07 PM, J. Forster wrote:
> Hi Al,
>
> John Franke sent me some V-I plots off-list. They show very little
> difference between a sweet spot on a Galena crystal and a Ge diode.
>
> Best,
>
> -John
>
> ===========
>
>
>
>> Mike,
>>
>> Yes, I have.  Overall, this detector is not very sensitive, get
>> something going with a germanium diode, so you know you're in the
>> ballpark.  One of the tricks is to scratch part way through the bluing
>> on the blade.  Some suggest there is selenium, a semiconductor material,
>> involved in the coating.  There is, of course, carbon, another
>> semiconductor, involved in both the pencil lead and the high-carbon
>> steel.  I've had success with the hardened edge of other, non-blue,
>> blades.
>>
>> There's potentially useful info on my site here:
>> http://www.skywaves.ar88.net/xtal/xtal.htm
>>
>> I highly recommend the PGXS circuit if you're going to wind a coil.
>>
>> Build a crystal set.  It's good for your soul,
>>
>> Al
>>
>> On 8/6/2012 11:58 AM, mstangelo at comcast.net wrote:
>>> Has anyone ever tried building one of these foxhole radios?
>>>
>>> I started my journey inot electronics, like may others, by building
>>> crystal radios.
>>>
>>> I got my crystals from a neighbor who was an electronic technician . My
>>> first crystal was in a bakelite case. I forget the number but I still
>>> have it
>>> somewhere. The tapped coil was built on a schellaced toilet paper roll.
>>> My headset was a high impedance crystal earpiece.
>>>
>>> I lived in Queens New York at the time and could easily pick up WCBS
>>> 880.
>>>
>>> I read about the foxhole radio which used a Gillette Blueblade and the
>>> pencil graphite as a detector. The graphite was held with a safety pin.
>>> I got hold of the blade and graphite and tried it but could never get it
>>> to work.
>>>
>>> Has anyone hasd success with this type of detector? If I could get my
>>> hands on a Blueblade I'd try it again.
>>>
>>> Mike N2MS
>>>
>>>
>>> ----- Original Message -----
>>> From: Hue Miller<kargo_cult at msn.com>
>>> To: milsurplus at mailman.qth.net, tetrode at googlegroups.com,
>>> Wireless-Set-No19 at yahoogroups.com
>>> Sent: Sun, 05 Aug 2012 22:54:12 -0000 (UTC)
>>> Subject: Re: [Milsurplus] Foxhole Radio - conclusion
>>>
>>> The opinion was also expressed that soldiers have often have time on
>>> their
>>>
>>> hands, where boredom is an issue: thus, they would relish some activity
>>>
>>> like the opportunity to build 'foxhole radios'.
>>>
>>> <snip>
>>> ______________________________________________________________
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>> --
>> Al Klase - N3FRQ
>> Jersey City, NJ
>> http://www.skywaves.ar88.net/
>>
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>
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-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/