[Elecraft] KPA500: birdies on 6m from LCD backlight

[Joe Hall]

Just got a KPA500 kit a couple of weeks ago (S/N 2380).  Upon installing it
in my system I immediately noticed sharp spikes about every 9.5 kHz (only on
6m) in my panadapter.  These spikes are "audible" on my K3 and appear
whenever the KPA500 is on, whether in standby or operate.  Nothing at all
noted on any band other than 6m.  

A google search of the mailing list archives revealed a couple mentions of
the KPA500's LCD backlight.  So, I went in and adjusted the LCD brightness.
Dropping the brightness to "DAY" (which seems to turn the backlight totally
off) completely clears up the spikes on 6m, any setting other than "DAY" and
it's there - I can switch back and forth and watch the spikes appear and
disappear.

My email to elecraft support resulted in a response of "turn off the
backlight."  With no backlight the KPA500 display is unreadable in my shack.

This is a relatively minor issue for me given that I rarely operate on 6m,
but I'm anal enough that I'd prefer to solve rather than accommodate the
problem.  

Anyone else seen this and/or have any ideas about how to deal with it, other
than turning off the backlight?

Thanks,
Joe / WB1M