[Hallicrafters] Transistors

[Carl]

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 In modern wireless communication systems, galena detectors have been 
replaced by more reliable semiconductor devices, though silicon 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