Yaesu FT-991A and ATAS-120a Tuning Issue

I have everything strapped and bonded with braided bonding wire yet for some reason the 120a will not tune on anything except 70cm, 2m, 6m, and 10m. If I go any lower in bands, the SWR meter doesn't even show anything and the "unable to transmit" flashes (receive indicator flashes with no "HI-SWR"). It is almost like it is just moving the antenna up and down but isn't even bothering to see what SWR match the Antenna is getting with the radio and band.

[@ncoldmanoverland]

Mine does the same thing, initializes, goes all the way up, then all the way down. Then gets stuck in the down position. How did you resolve this?

[@mmlanger55]

Your windshield does not provide you a ground barrier to your radio chassis. You have rf coming back into the cab. My roof mounted ATAS-120 tunes just as they claim. Good luck with yours.

[@CT7BHW]

Bro , you have to be a great great great grounding!!!! First of all ok!? 73s

[@ChessWithMouselip]

Did you get this fixed? I have the ATAS-120 mounted on the back of my Sentra with a FT-891A and it works great. Make sure your mount screws are going into metal not just paint.

[@donsdoityourself2547]

Try putting an good quality RF Choke on the antenna input to the radio. I have an FT-991A and the ATAS-120A which I just bought. It would not tune. It would do erratic things and run right past the low SWR. I believe there was some common mode issues going on which screws up the digital communications. With the choke, it is tuning quickly and stops on lowest SWR.
BTW... it would tune 2M and 70C and 10M.... I think the common mode feedback is worse on HF frequencies below 10M.

[@KuehncIncorporated]

RF Grounding is super important

[@chrish1922]

I wanted to use my ATAS-120a on a 2000mm long pipe, you don't try that the atas won't find a match, also 8x 2000mm long radials in the rain failed. If you don't have an coach for driving/living/having fun you might throw the atas into the trashbin

[@cprendon3]

Too far away to read the screen and no explanation. Don't know what we're supposed to get out of this.