(MOBILE) 991A AND ATAS-120A tuning issues

[Ghostnotes]

I did not want to start a new thread. I searched the threads but nothing really came up.
I have my antenna mounted to the bed of the truck and seem to have some tuning issues. I haven't installed any separate ground straps yet, but the antenna base is mounted directly to the body and the receiver is wired directly to the battery. It blows past the low SWR on 10M half the time. I'm thinking there might be some common mode issues happening. I'm thinking of installing a choke perhaps to see if this will help. Can someone recommend one and also a good duplexer for this setup?
Thanks!

 

[popnokick]

What is your need for a duplexer and how do you anticipate using it?

 

[Ghostnotes]

What is your need for a duplexer and how do you anticipate using it?

So I don't have to keep plugging and unplugging my antenna when I go from HF to VHF/UHF and vice versa...

 

[K9KLC]

Can someone recommend one and also a good duplexer for this setup?

You're gonna be a lot happier on 2 meters and 70 centimeters if you use a separate antenna for those and the ATAS for 6 and HF.

 

[popnokick]

I get it.... one antenna (ATAS) for everything. A duplexer like the Comet CF-530C or Diamond MX62M will allow you to split the ATAS coax between the HF / 6M and VHF/UHF antenna ports on the 991A.
Comet Antennas CF-530C Comet Duplexers | DX Engineering
Diamond Antenna MX62M Diamond Antenna Duplexers | DX Engineering

 

[Mikejo]

I’ve tried this out with the FT-857D, a duplexer, and the ATAS120. And it works, but I began to wonder about as the wear and tear on the ATAS120 overtime, possibly something for you to think about.

 

[Ghostnotes]

I get it.... one antenna (ATAS) for everything. A duplexer like the Comet CF-530C or Diamond MX62M will allow you to split the ATAS coax between the HF / 6M and VHF/UHF antenna ports on the 991A.
Comet Antennas CF-530C Comet Duplexers | DX Engineering
Diamond Antenna MX62M Diamond Antenna Duplexers | DX Engineering

Okay so I'm on the right track, I ordered the 62M prior to this post. It comes down to room for me. I already have satellite, GPS enabled alarming,amplifiers etc, so wiring room is at a premimum. My running boards are full.