Two antenna solution?

[ecgreen]

Hi guys,

I have an idea, and just want to get some opinions. Here is the deal:

I have a 2 meter antenna mounted on the bed rail in the back of my Tacoma. The antenna works well enough, I can hit repeaters within 10 miles and it is more than fine for trail use. So here is the thing - I would like to be able to hit more distant repeaters and have better transmitting capabilities when on the road. My thought is to have two antennas hooked to a switch like this:

https://www.gigaparts.com/MFJ-1702....xMcsdO1DgZhA-oH0v0yu9Ajw8YfXvEvEx6RoCLP3w_wcB

I would keep the bed rail mount and put a through the roof NMO mount on top of the truck for increased on road capabilities. Now, I live in New Hampshire, so offroading = trees (and pin-stripping...lol). I am thinking that off road, I can switch to the rear bed-mounted antenna and put a rain cap on my roof mount:

http://www.neobits.com/laird_techno...WIgcNxdmc9xXBMuF5Mbk-p2ZpD57n3r_VSxoC6Snw_wcB

I am thinking that the rain cap will protect the NMO mount (and attached roof) on tight overgrown trails.

Thoughts?

 

[Chris Boyd]

Sounds like a fine plan. The NMO mount will be some work, but doable and will have a good ground plane. A good 1/4 wave or better 2m will play nicely.

Depending on what rig you're running you might also want to just consider swapping bed rail antenna to a base-loaded higher gain antenna which is also multi band 2m/440cm when on the road. Something like the comet super beam or similar. I can hit APRS repeaters more than 30 miles away with that setup mounted on my rear hatch.

 

[wirenut]

Your plan will work. However, if you're going to be taking the top one on and off and installing caps I think I'd just swap between antennas. I'd get something like a rubber 1/4 wave for on the roof for trail work and then something like a Diamond Super Gainer for going down the highway. You could even use an adapter or two and mount the rubber duck from an HT on the roof mount. It would be really short and cheap if you broke it.

 

[Frdmskr]

Get a Larsen NMO it will work great and take a beating on the roof. The whips are indestructible and the coil is low profile enough unless you wanna go thru a rock or tree.


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[malibubts]

I'd agree with the other folks here saying to use the roof NMO all the time. You will have a much better ground plane and get better results.

I have a Diamond NR72BNMO, which is pretty compact and only about 13 inches. I can easily hit repeaters 30 to 40 miles away at 50W. As someone else suggested you could even swap that out for a rubber antenna when on the trails. I think the bed mount and switch just adds unneeded complexity. The Comet SSB1 looks to be a little longer at 16 inches but it is flexible. Maybe someone else can chime in with a better off road antenna.

As far as the NMO mount itself. Take a look around at local shops and see what they would charge to install. I found a shop that drilled the hole, installed the mount, ran the cable down the pillar for $35. They did an excellent job and it was a steal.



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[DaveInDenver]

On my old truck I ran an NMO on the cab roof and swapped between antennas. For trails I used the STI-CO Flexi-Whip. They take a beating for sure and are so low profile that you'd literally have to have the roof scrape the obstacle. The base is lower profile than the NMO cap you'd use.





I actually used individual antennas for 2m and 70cm because I had two NMO mounts (originally I had two antennas, one for voice, one for APRS until I got an FTM-350). I used a diplexer.

 

[ecgreen]

Thanks for all the great replies! Let me ask this:

How much better is the performance on you roof mounts versus mounting somewhere else? are see an improved range that is worth the work of the roof mount install?

 

[Airmapper]

Roof mounting was not a reasonable option for me as my roof rack takes up the entire roof space. I'm in the process of changing that setup, but up till now I've had to find somewhere other than the roof for antennas.

What I came up with is dual NMO brackets on the front fenders, one on each side. Some vehicles you can buy the mounts, I fabbed mine out of stainless sheet and a sheet metal bender. In my case they use an existing fender bolt to mount.

On the drivers side I have a fold over 5/8 wave 2M/70cm antenna. It has hit APRS repeaters over 100 miles away but that was an ideal situation. I can talk on it in the 15-20 mile range to nearby repeaters while mobile typically. Most of the time I run 10 watts and have no trouble, if I'm way out I can bump up to 50 watts. I have been running around in one city and talking on the repeater in the next county over many times.

On the passenger side I have have the option to attach a whip for the CB. This is rarely used so I have a cap on it 99.9% of the time. I don't think the performance is very good but it's been adequate for typical trail comms.

So I guess my point is if the roof is not practical, don't be afraid of fender mounts.

 

[prerunner1982]

Thanks for all the great replies! Let me ask this:

How much better is the performance on you roof mounts versus mounting somewhere else? are see an improved range that is worth the work of the roof mount install?

When I switched vehicles I went from a roof mounted NMO antenna to a fender mount (same antenna, same radio, same model vehicle) and definitely noticed a difference in TX and RX distance. Some of the repeaters I could barely make it into to begin with I now have problems making it into. Wasn't a considerable change, but enough that I could tell it was reduced.

 

[mjac]

Between these two mounting locations, rear lip of hood near fender or high on rear hatch, which is favored?

Fender is not an option on my T4R.

A Comet SSB1 rubber ducky will be used on the trail and Larson 2/70 31" whip for the open road.

 

[Hillbilly Heaven]

My vote is high on rear hatch. The higher you can get above body the better. The front fender mount or lip of hood is directional because of the reflection from the passenger compartment.

 

[Hillbilly Heaven]

I have a suggestion to anyone that runs any antenna with an open coil winding on the antenna. Take a piece of heat shrink or if you don't have any that will fit you can use electrical tape and cover the open coil windings. I have managed to snag tree limbs in the winding. I know what are the odds of it happening but it did. Murphy loves me!