ft8

Sounds like CMC/RF issue to me.
Check on dummy load and come back with result.
Mike

use special usb cable model Tripp lite U023-006it has the ferrite and every wire has grounding around it.
I use i on my ft dx 10 and IC 9700 no RF problems.

ahasverus said:

tnx fr reply will put ferrit rings around each cable at the beginning and at the end i have also a yaesu 1200dx with scu interface and i have no problems i am curious why the dx10
do it possible the ft8 is build inside (mode preset ) what can i aspect using dummy load on3bm 73

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By using a dummy load, you can test the radios power output. If you transmit 50 watts into the dummy load and the power remains steady, then you know the radio is okay.

You need to be careful using the dx10 radio on digital modes. I have a friend who has had to get his dx10 fixed twice now in the last year. The power transistor in the PA section quit working both times. I've told him not to run the radio at 100 watts, because digital modes work the radio at 100% duty cycle, which can put a lot of stress on the final. Although there seems to be a lot of people who run there radios at 100 watts while using digital modes. That's based on watching videos.
I have a ft710 and I assume it has the same PA circuit as the dx10, and I run the radio at 20 watts max. I adjust the rf power through the ft8 program to 15 watts. I've actually made 5 japan contacts one day while running 10 watts, and I'm using a Zero 5 vertical antenna. I actually do run 20 watts on psk31 mode. My point is that ft8 is a week signal mode so you don't need a lot of RF power.

Sorry for the long post, but basically if transmitting into a dummy load and the radios power stays steady, then you probably have a problem with your antenna system like the others have mentioned. Although, you said that your 1200dx works fine, which sounds like a problem with your dx10 rather than the antenna system.