Fw: KPA500 Power out query.

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   ----- Forwarded Message ----- From: Mike Streeter <[hidden email]>To: [hidden email] <[hidden email]>Sent: ‎Saturday‎, ‎January‎ ‎27‎, ‎2018‎ ‎12‎:‎04‎:‎40‎ ‎PM‎ ‎CSTSubject: KPA500 Power out query.
 I am driving my KPA500 with my K3 to a Mosley PRO 67. On every band except 20 meters 25 watts out from the K3 will give me at least 500 watts out of the amplifier. On 20 meters I get 450 watts out with 25 watts drive but no increase even if I go to 40 watts out from the  K3. I have put a dummy load on the K3 using the usual RG 213 and the SWR is 1:1, and I have checked the antenna with an MFJ 259, using the usual RG 213 cable and it is 1:1 at 14.000 up to 1.4:1 at 14.350.I have loaded the latest firmware to both the K3 and the KPA. I realize that the difference between 450 and 500 watts is negligible but it bugs me that it is not giving me full power out on 20.Anyone have any ideas as to how to fix it?Many thanks, Mike, WM5DX.
 
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[AJ8MH-Radio.Joe.Hutchens]

My amp is close to 7 years old and 20 has always required more drive. 
27 to 30 watts on all bands except 20 where I'll run it up to 35 in a
pinch. Elecraft suggested I send it in, but I haven't let the smoke out,
yet.  Unlike your issue, I see a change when I increase drive. I drive
the amp with either a Yaesu FT-950 or a FTDX3K.  ALC is not wired. 
There is a modification kit out for the amp, but have no idea what it
addresses.

Also, heat causes some stress on the chassis and you'll here pings as it
flexes with temp.  The first time I heard that, it scared the heck out
of me.  I believe there is a fix for that, too.

Joe
( www.aj8mh.com )

On 1/28/2018 10:57 AM, Mike Streeter via Elecraft wrote:

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