ATAS 120a & Larsen 2/70 into FT-991???

[dbssteagall]

OK, so I'm new to the hobby and not licensed yet. Classes start next week and I'll take the test in about a month but I'm getting prepared for being able to TX soon.

So I bought a Yaesu FT-991 with an ATAS 120a thinking that I was set for everything. I found out in the general section here that I would need another antenna for 2 meter and 440. Which for me will be important for me. So I guess I'll add a Larsen NMO2/70B to the list.

So I guess if someone could help me with a few things I would be so grateful.

There are two coaxial antenna connections on the back of the FT-991. An HF connection and a UHF/VHF connection. Although I'm going to have an installer mount the antennas and hook up the radio, I don't even know which antenna goes to which connection.

I also plan on mounting the antennas to the top of the bed of my truck behind the window. The ATAS 120a on the driver side and the Larsen NMO2/70B on the passenger side. Will I get any interference or have problems with them being so close to each other?

I also will need something to switch between antennas like a duplexer? when I change frequencies and I would like help with that as well.

I have read K0BG.com about grounding and have grounded all four corners of my bed to the frame and both sides of the cab to the frame and when the radio is installed I'll have them run a ground cable from the ground on the radio to the grounding post in the engine compartment.

Is there anything I'm missing? I hate to ask so much but I don't have an Elmer yet and I thought the brain power here might be able to help without even breaking a sweat!

Thanks in advance

~David

 

[mrweather]

I'm not an owner but the ATAS-120A apparently covers HF, VHF and UHF. If that's the case, you don't necessarily need the NMO2/70B (though it's a very good antenna).

Because your radio has separate HF and VHF/UHF antenna jacks you'll need a diplexer to split HF and VHF/UHF signals from the ATAS-120A. Something like a Comet CF-360A. Basically plug the ATAS-120A into the SO239 jack on the diplexer and on the FT-991 you plug the HF cable from the diplexer to the HF antenna jack and the VHF/UHF cable from the diplexer to the VHF/UHF antenna jack.

Now, if you're happy with having separate antennas, plug the ATAS-120A into the HF antenna jack and the NMO2/70B into the VHF/UHF antenna jack on the FT-991.

 

[prcguy]

The Larsen NMO 2/70B is an excellent antenna and will perform much better than the ATAS on 2m and 440. The ATAS-120A is near the bottom of the list in performance for HF antennas and a $20 Hamstick will easily do better. It would be nice if you could return the ATAS and get something better like a Little Tarheel on the low end or bigger is better.

The HF port on the radio covers 160 through 6m and the VHF/UHF is for 2m and 440, so at least the band splits of your antennas are good match for the connectors on the radio.

Do good on the test then get on the air and enjoy your new hobby.
prcguy

 

[dbssteagall]

Thanks a lot guys. I'm still not sure which way to pull the trigger yet, but I figure I'll have lots of time to figure out what the best for my situation is. One I get everything in place I will try and post pictures of the setup. I've not seen many pictures of an FT-991 installed in a vehicle yet.

~David