flex 1500 low power 17m, why?

I have the same problem on 160m with 30w maximum. Other bands are ok. I will have to send it in for repairs but that will be some time next year as I am a pensioner.

Check your power out into a dummy load as W7ZAC has done...see above comment. Antennas can cause funny problems causing high SWR.

1.  Check to see that you are running the current version of PowerSDR

2.  In the absence of a dummy load, use a low wattage light bulb as a dummy load.  Try the light bulb on 20 meters first to make sure that the 1500 will put RF into the bulb.  Then, if the radio shows output, switch to 17 meters.  A 220V bulb should work fine.  For my high power radios I use a 100 to 125 watt bulb, for my low power radio I use a 40 watt bulb.

While there are better ways to make a dummy load, this should work if nothing else is available. These bulbs will not light.

You can also use a  12V or 24V automotive bulb.  Make sure the wattage is greater than 5 watts. The bulb should light somewhat with a 10w bulb.

I am sure that readers on the list will critisize me heavily for suggesting this; but, I have used this technique for many years when I don't have a dummy load available.