[Elecraft] Highest power supply voltage for K2?

[G3VVT at aol.com]

In a message dated 30/11/04 02:01:23 GMT Standard Time, althoff at verizon.net  
writes:

What is  the absolute highest safe voltage you can pump into the K2 before 
you start  overheating the regulators etc? 


Most manufacturers seem to give 16V as the upper sustained voltage limit  for 
DC input on 12V equipment. The 2SC1969 PA transistors are rated at this in  
their data sheets and the regulators seem to come out at 25V as their maximum  
input so should not represent a problem.
 
Faced with the situation you have with 1.2V above the 16V normal limit a  
string of 1N4000 series 1A diodes could bring down the voltage to what you  
require. Normal forward voltage drop comes out somewhere near 0.6V per diode, so  
two in series would probably fit the bill. Used this technique to power a Sony  
2001 SW broadcast radio I had in the Middle East for over 20 years needing  
4.5VDC power source.
 
Bob, G3VVT