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

[Buck]

Another interesting side note - the 12 volt rail in the K3 is "ON" all 
the time, even when the K3 is turned off.  I found that out when one of 
the finals developed a partial short and the radio was drawing 2 amps 
when turned "OFF."

If you are not using equipment, find a way to disconnect the power or 
turn off the power supply.

Buck, k4ia
Honor Roll
8BDXCC
EasyWayHamBooks.com

On 7/1/2021 11:54 AM, Hal Massey wrote:
> Maybe so. But this is an old design.
> 
>> On Jul 1, 2021, at 04:50, David Woolley <forums at david-woolley.me.uk> wrote:
>>
>> 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.
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