XPost: rec.radio.shortwave   
   From: bit_bucket@gmx.com   
      
   On 11/17/2011 5:18 AM, dave wrote:   
   > On Thu, 17 Nov 2011 07:34:03 +0000, Geoffrey S. Mendelson wrote:   
   >   
   >> Michael Black wrote:   
   >>   
   >>   
   >>> Of course, towards the end of the life of tubes, one could get some   
   >>> that ran off 12v, intended for use in car radios.  Not so useful now   
   >>> since they were produced in a limited time span as transistors were   
   >>> taking over, so quantity is relatively limited.   
   >>   
   >> Even rarer were tubes that drew almost no current. They used "cold   
   >> cathodes" so they did not need expensive (in terms of current and heat   
   >> dissipation) filaments and had low plate voltages.   
   >>   
   >> They came out when transistors where just starting out, but rise of   
   >> transisitors was so rapid and transistors were so cheap in comparison,   
   >> that it was simpler and cheaper to build a 7 or 12 transistor radio than   
   >> a 5 tube cold cathode one.   
   >>   
   >> They showed some promise in the missle and space exploration systems of   
   >> the time, because transistors could not stand the temperature extremes   
   >> or cosmic radiation they would be exposed to. That also did not last   
   >> long, as improved "space grade" transistors came out.   
   >>   
   >> What really killed them was NASA's adoption of the new integrated   
   >> circuits (which actually pre-date the "space race").   
   >   
   > Cold Cathode tubes were voltage regulators, displays, etc. I have never   
   > seen a cold cathode amplifier.   
   >   
   > Between miniature tubes and solid state there were Compactrons, which   
   > were several tube stages in a single envelope.   
      
   There were tubes which contained a bit of thorium and required minimal   
   heater current.  The slight radioactivity is a no go, as well as the   
   potential pollution to the environment ...   
      
   Regards,   
   JS   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)