[Hallicrafters] Transistors

[Bob Macklin]

The 1n21 and 1n23 are point contact diode. I thought they were germanium.

The 1n34 was a germanium point contact diode. You could see the "Cat's
Whisker" through the glass.

Bob Macklin
K5MYJ
Kent (Seattle), Wa,
"Real Radios Glow in the Dark"
----- Original Message ----- 
From: "Carl" <km1h at jeremy.mv.com>
To: <dhallam at rapidsys.com>
Cc: <hallicrafters at mailman.qth.net>; "TC Dailey" <daileyservices at qwest.net>
Sent: Wednesday, June 03, 2009 3:51 PM
Subject: Re: [Hallicrafters] Transistors


I couldnt think of that word when I wrote that.

Here is a bit more from Wikipedia:

Galena is a semiconductor with a small bandgap of about 0.4 eV which found
use in early wireless communication systems. For example, it was used as the
crystal in crystal radio sets, in which it was used as a point-contact diode
to detect the radio signals. The galena crystal was used with a safety pin
or similar sharp wire, which was known as a "cat's whisker". Making such
wireless sets was a popular home hobby in the Britain during the 1930s.
Derbyshire was one of the main areas where Galena was mined. Scientists that
were linked to this application are Karl Ferdinand Braun and Sir Jagdish
Bose. In modern wireless communication systems, galena detectors have been
replaced by more reliable semiconductor devices, though silicon
point-contact microwave detectors still exist in the market.

Carl
KM1H


----- Original Message ----- 
From: "David C. Hallam" <dhallam at rapidsys.com>
To: "Carl" <km1h at jeremy.mv.com>
Cc: "TC Dailey" <daileyservices at qwest.net>; <hallicrafters at mailman.qth.net>
Sent: Wednesday, June 03, 2009 3:38 PM
Subject: Re: [Hallicrafters] Transistors


>I don't know about new crystal radio sets given the scare tactics about
>lead in recent times, but the old standby for a crystal was lead sulfide
>aka Galena.
>
> David
> KC2JD/4
>
> Carl wrote:
>> Ive always heard it was a standard old germanium or other bipolar found
>> in crystal set parts that had an impurity besides the one needed.
>>
>> Carl
>> KM1H
>>
>>
>> ----- Original Message ----- 
>> From: "TC Dailey" <daileyservices at qwest.net>
>> To: <hallicrafters at mailman.qth.net>
>> Sent: Wednesday, June 03, 2009 1:32 PM
>> Subject: [Hallicrafters] Transistors
>>
>>
>> The day is not wasted - I learned something. (FET)
>>
>> Tom - WØEAJ

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