[Elecraft] KPA1500 Power Supply noise

[David Needham]

My KPA1500 Power Supply is making a noise that has gotten progressively
louder over time when I transmit. It sounds like a hissing (but it is not
arcing) when I transmit. The noise is modulated by SSB speech or CW or
digital modes keying, louder at higher power levels now during the CQWW WPX
Phone contest.

I am pretty sure it is not RF getting into the Power Supply. I have
followed K9YC practices of bonding the K3, KPA1500 Power Supply and RF
decks to the ground bus. All cables going into and between are wound on
snap on or toroid ferrites.

Has anyone else run across this? I plan to open up the power supply and
check for loose parts and do some more testing after the contest.

-- 
Thank you!
David Needham, AA4VT (formerly K4AJA and K8AJA)