[Elecraft] KPA1500 issues/blown finals

[Jim Brown]

On 2/15/2026 12:05 PM, Jon Zaimes, AA1K via Elecraft wrote:
> Was this your study Hal? Has it been shared with Elecraft?
> Kind of defeats the purpose of buying a 1500 watt amp if it needs to be run at lower levels to survive. There are less expensive amps for that.

The study is in conflict with my experience. My KPA1500, purhased about 
a year after they started shipping, has been in service for more than 
six years, with no issues of the sort it describes. I'm an active 
contester, and regularly run it near legal limit on CW and RTTY. The 
only time it's been in for service was due to a failure in the antenna 
system that caused a failure in the tuner (an EXCELLENT tuner, BTW).

I generally run it around 1.25 kW for VERY long duty cycle WSJT modes on 
6M (meteor scatter, and weak signal work that utilizes TX cycles of as 
much as 2 minutes, and can extend for hours; there's a non-destructive 
failure mode caused by device heating that melts the solder and allows 
them to fall out of the board; repair consists of reinstalling them.

I've found the amp to be EXTREMELY well protected -- at 84, I often make 
mistakes changing bands during a contest that activate the protection 
system.

I recently bought a very early serial number unit in which devices had 
failed and been replaced. I sent it to Elecraft for repair. They said 
the amp was not working properly because the new devices had not been 
biased, which is a critical part of replacement. Unlike the JA mfrs, 
Elecraft makes running production changes over the years based on 
service experience, which may have happened with this product.

I like to have spares for important parts of my station. My early 
vintage K3s, mostly upgraded to K3S, are spares for my K4. This used amp 
is a spare for the one on my operating desk.

73, Jim K9YC