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

[Roger Marrotte]

Hi Joe,

I have KPA500 S/N 2381.  Mine was a kit also.  I just checked out 6 meters
and can hear no birdies that seem to coming from the amp.  I hear just a
couple that are there with or without the LCD backlight on.  Same results
with the amp off or on.

Roger, W1EM

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Joe
Hall
Sent: Thursday, February 26, 2015 2:48 PM
To: elecraft at mailman.qth.net
Subject: [Elecraft] KPA500: birdies on 6m from LCD backlight

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



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