No Tune output on 40M Flex 6300. High SWR into a dummy load

Dennis Terry W4SG

I have a Flex 6300 without a built-in tuner and it will tune into a dummy load without any problems on all other bands except on 40M where it give very high SWR and no output power.  All other bands work as expected. 10W and SWR less than 1.5.  Does it need a trip to Austin or am I doing something silly?
During normal operation I use an external KAT500. This is the first time I have tried to use 40M as I did not have an antenna that was capable of 40M.

Bill -VA3WTB

On a dummy load it will not tune on 40m?

Andrew Thall

First, eliminate the obvious.  Check your coaxial cable.  Sometimes, the length of the cable can be resonant and will reflect power back to the radio.  Swap the cable for a different length.  Back the power way low and try the antenna with the tuner.  If all this fails,you may have a problem.  Do you know anyone who has an antenna analyzer?  Also, try a different antenna -- perhaps just a long random wire with the radio to see how it behaves.GLAndy, k2oo

K5CG

If you have a built in tuner, make sure it is bypassed.

Bill -VA3WTB

even on a dummy load?

Dennis Terry W4SG

Correct, all other bands 160-6M tune FB.  I have the power set to 10W tune power and have eliminated all other cabling and went from the 6300 to the Palstar DL2K.  Originally I went from the 6300 to the 811 to the LP-100A then to the KAT500 and tried my antenna and it did not work.  The KAT never tried to tune it as there was no power.  Then I tried the dummy load which is always connected to port 3 of the KAT500, neither worked so I went from the 6300 to the DL2K and that does not work either. There must be a coil or other device unique to 40M in the 6300.

Mark WS7M

And before shipping back export your profiles and try a factory reset.

Bill -VA3WTB

Try connecting the dummy load directly to the flex antenna port

Bill -VA3WTB

If you read his post, he said he does not have an built in tuner.

K5CG

Yup, missed that.

Bill -VA3WTB

I think Mark is correct, a factory reset may help.

W7NGA

You may have inadvertently selected a different output port on 40-meters that has no load. Check receive and transmit ports haven't changed. I've seen something similar that only a factory reset would fix.

Dennis Terry W4SG

Factory reset seemed to fix it. Never thought it would have an effect on just one band. I only had a couple of profiles and wanted to redo them anyway so did not save them..

Dennis Terry W4SG

Factory reset seemed to fix it. Never thought it would have an effect on just one band. I only had a couple of profiles and wanted to redo them anyway so did not save them..

Dennis Terry W4SG

That is what could have happened but I did not look close enough to the antenna selection to catch that as I only used one port plus the transverter port for 2M.

Dennis Terry W4SG

Thanks to everybody for their ideas, I love this forum to get things resolved with a minimum of pain.