Face is red - Issue resolved - senior moment - yep the transformers are
energized anytime its plugged in and the
"ON-OFF" switch on the input voltage /fusing module is "ON". Been so long
since I looked at back of amp
after I finished it and hooked it up , I forgot that was a real switch. Nice
to have gear so trouble free you
forget what the back looks like !!!! Some part of the PS HAS to be on for
voltage for the logic.
Thanks to all who responded
Hank K7HP
-----Original Message-----
From: Hank P
Sent: Saturday, August 01, 2015 12:49 PM
To: Elecraft Reflector
Subject: Re: [Elecraft] KPA500 power supply
Since we are in monsoon season here in AZ - if any storm is in area or
predicted - I disconnect everything - both at tower and at shack wall.
I noticed this morning that when I plug the KPA500 back in -(its on a 240
circuit all by itself) I hear what appears to be an initial transformer
magnetizing input hum even though the ON switch is OFF .
All seems to be working fine - going from ON to OFF the fan runs to bleed
down the PS and amp works OK - I just never noticed this hum before .And
the hum is just at the initial plug in - it does out to inaudible.
It appears even when the KPA500 is "OFF" the transformers are still being
fed from AC line - TRUE ????
Sheet 1 of 2 of the PS shows a "switch" right at input but that appears to
be part of the input 120/240 module , KPA500 Front Panel Switches shows the
"ON-OFF" sw just as a closure to ground feeding control logic at which point
I get crosseyed.
Hank K7HP
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