[Elecraft] KPA100 damaged by open circuit output

[Don Wilhelm]

Harry,

I would replace those components that look damaged.
When you begin testing it again, first set the bias.
Then unplug the power cable to the KPA100 and power only the base K2.
Run the base K2 at 10 watts while nulling and adjusting the wattmeter 
potentiometers R26 and R27.
Once you have done the above, power the KPA100 once again and touch up 
the wattmeter reading at 80 or 100 watts.

73,
Don W3FPR

On 8/9/2017 9:53 AM, harry weston wrote:
> Hello
> A while ago I built a KPA100 to go with my K2, but unfortunately was careless while testing it and accidentally fed its output at a high power into a cable with a bad, open circuit PL259 connection. Whiff of magic smoke, panic, and I found several components in the TR switch badly scorched. The obviously damaged items are: R21, R13 and C71, and the 1K resistor across RFC3 is black and open circuit. RFC3 itself appears undamaged, and its inductance measures 88 micro-Henries.
> My question is, please: is it ok just to replace these burnt components, or is there likely to be further unseen damage that I should also allow for? If so what else should I replace, or are there any special tests I can do to find out?