SWR is always 9.99 when using 40m bands

[verifiedpen]

I use a long wire as antenna (about 10 meters) connected to an antenna tuner.

When using 20m on CW mode (tr)uSDX shows my SWR is around 1.2 which is great. But when using 40m, no matter how I change the antenna tuner or even change the length of my wire slightly it stays at 9.99. How accurate is this reading? Is there something I'm missing?

[dl6sez]

Hello OM,

does it also 9.9 with a dummyload?
I can't believe that it is a fault on (tr)uSDX, because it does work on other bands.
It is quite good accurate, i would think abt. +-10%.

73 de Chris

[verifiedpen]

Hello,

I don't have a dummy load unfortunately. If there are no limitations on the device itself then I guess I will have to try different antenna lengths.