ATAS -120 tuning problem?

[AE2B]

My name is Eddie Barra call sigh AE2B. I have an atas-120 for my 100D. It is mounted on a 2003 GMC Sierra dually crewcab 4x4 with the duramax diesel and is grounded very well. It is bolted directly to an existing bolt from GM that goes from the bottem of the rear L bumper to a bracket welded to the frame by GM. I Then a made a custom steel tubular mount that is welded to a 1/4 inch steel flat piece goes out to the left from the bottem of the bumper out far enough to clear the rear left taillight then up 4 1/2 ft to a small flat steel surface and is mounted directly on that with nothing but metal on metal. It  puts the whip and tuning coil above the roofline and is 8 feet away from the roof itsself. It tunes from 440 to 40 M no problem except 6M. It trys to tune it but it comes up antenna error. Does anybody have one with a similar problem or has any ideas? Please e.mail me at MY24K86TA@AOL.COM. thankyou and see you on the air. 73 to all

[K9PO]

I have the same problem and have not found an answer.

I cannot offer any ideas but you are not alone.

[N3EOP]

Old problem.

Take about 10 feet of coax and make a coil about six inches across.  You'll get four or five turns out of it.

Either tape it into a coil or use a few wire ties to hold it.

Put the coil in the antenna line, preferably as close to the antenna as you can.

It's a cheap fix for a lot of "won't tune" issues with the ATAS.