[Elecraft] K3/KPA500/KAT500 SWR problem

[John Bastin]

On 29 Dec 2013, at 5:46 PM, Ray Coles <raycoles96 at gmail.com> wrote:

> I also note
> that when I start transmitting, power is always less than I have selected
> and it climbs steadily to the demanded value over time. I have set up ALC as
> documented. If I set power greater than 40W (this varies a little band to
> band) the power climbs until....BAM!.... The SWR of 1 to 1.4 suddenly shoots
> up into the Red with the KAT500 utility recording values of 5-25!

I agree that first you should connect your output directly into a 50 ohm dummy load and see if you see the same symptoms or if everything looks normal. If it's normal there...

Your symptoms of SWR jumping up as the power is increased seem very indicative of a bad coax shield connection on your RG58 or RG8 feedline. I would carefully inspect your PL-259s and any barrel connectors that may be involved in the feedline path to the antenna, for looseness in the shield connection to the PL-259. Probably best would be to make up a new coax feedline with new connectors and make sure the solder connections to the shield side are very solid.

Hope this helps.

73,

John K8AJS
jbastin1 at me.com