[Elecraft] K3 strange overshoot

[tony.kaz at verizon.net]

I got way behind with my personal email so not sure if there has been follow-up to this.
I have a K3/KPA1500. A final in the KPA1500 blew and took out the K3 too. Both went back to Elecraft for repair. This was the third trip back for the KPA1500.I was told the log showed over drive on the amp. This was very puzzling as I never drove the amp hard, at least not to my knowledge. I was concerned about using it. Thought about selling it as it was fresh back from the factory again and checked out. But not sure if there was an inherent problem with the amp so didn't want to pass this on to someone else. When it came back I left it in the box for quite a while. Used the KPA500 instead. Finally set it up for ARRLDXCW. But kept my drive at <20W. My amps are in the basement on a shelf literary right below my feet where I sit to operate. My left monitor is off about 45 degrees. This is where I have a window for the KPA1500 Remote screen window. What I noticed, even with <20W drive, when I changed any bands, the first key shot the power way up. After the first keying the power dropped down to what you would expect. Any keying after that would be fine until I changed bands. Maybe this is why the KPA1500 finals died?
I was told this is caused by the K3. If you set the K3 to exactly 5 or 50W the calibration will change and cause this spike. Someone told me to do a recalibrate on the K3 (sorry I don't remember who told me to do that? This K3 had come back from Elecraft along with the KPA1500.I did that and guess what, the spike on the KPA1500 went away even when changing bands. Since I did this I make sure the K3 is never set up for either 5 or 50w. Everything worked fine all weekend, but with reduced power. I was eagle eye when changing bands and so far have not seen the problem come back.
Is this K3 issue about the problem happening if you set up and transmit with the K3 at 5W or 50W for real? Is it widespread? I have to assume Elecraft isn't aware of this, if it is a real problem. I got to assume they would have sent out a notice or a possible software upgrade to fix this.
Bob, no idea if this is the overshoot problem you are seeing. 
By the way, what drive power are folks using to get 1500W out of the KPA1500?Also, I don't believe the SWR has had any involvement with this problem. All my antennas SWR are below <1.5.
73,N2TK, Tony


-----Original Message-----
From: Jim Brown <jim at audiosystemsgroup.com>
To: elecraft at mailman.qth.net
Sent: Fri, Feb 11, 2022 5:34 pm
Subject: Re: [Elecraft] K3 strange overshoot

On 2/11/2022 2:06 PM, Bob McGraw wrote:
> I see a small initial overshoot when changing bands. Drive power for 
> each band is different.

Same here. I think it's the K3, and I think it's normal.

73, Jim K9YC
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