[Elecraft] KPA1500 gain jumping on 160

[D. Drake]

I had the same problem with my KPA1500.  The exciter was an Icom 7610.  I my case I saw it on other bands to but it was more intermittent.  After some troubleshooting I concluded the trouble to be in the negative feedback loop in the PA.  I talked with the tech at Elecraft, he agreed and he sent me a pic with some spots highlighted to look for poor solder joints.  One did look suspicious so I reflowed it.  Since then it hasn't happened but I don't think reflowing that joint really fixed it.

Now that you have seen the same thing I'm more suspicious of a defective component.  Probably a bad cap in the feedback loop.

I suggest you call Elecraft and ask to talk to Rene Morris about it.

73,

Dale AA1QD

-----Original Message-----
From: Steve Masticola [mailto:steve.masticola at verizon.net] 
Sent: Wednesday, April 06, 2022 2:56 PM
To: elecraft at mailman.qth.net
Subject: [Elecraft] KPA1500 gain jumping on 160

Has anyone else seen the kind of gain jumping on 160 shown here?
https://www.youtube.com/watch?v=LjfksHwLz9w
The exciter is a K3, and I generated the drive signal by putting it into TUNE mode. The KPA1500 is feeding directly into a dummy load, so the antenna, etc. is not the cause.
I believe I heard about a "160 gain reduction mod" to correct this problem, but I can't recall where I saw it.
73, -Steve WX2S