[Elecraft] Temperature or Warmth of KPA500 when "Off" ?

[David Woolley]

I don't think this design would be acceptable in modern consumer 
equipment, at least not in Europe. Typically they would have an 
auxiliary power supply for the microcontroller, to reduce power 
consumption to well under 1 watt, and maintain a reasonably good power 
factor, when in a soft power off state.

Current and voltage figures quoted elsewhere in the thread suggest over 
10 watts and an unknown number of VA.  There was a lot of campaigning to 
hard power off devices at a time when standby powers were more like 5 watts.

On 01/07/2021 00:09, Jack Brindle wrote:

> It is powered by the 5V linear regulator, which is providing the heat you feel, along with the +12V and -12V regulators (also linear). I seem to recall that the input to the regulator is something like +15 or +18V, which gets regulated down to the three supplies that are used for running the microcontroller the RS-232 interfaces and the LCD. The LCD is disabled when front-power is off.