2M Install - 5/8 wave on roof rack? (1 Viewer)

[lovetoski]

I am studying for my ham test. Going well, excited to move to that communication medium. I bought a Yeasu 2900R since it's on sale at HRO for $119 (and free shipping). I've read through a bunch of threads on here and on expo, and the obvious antenna choice is a 1/2 wave larsen whip (150B hw) mounted on the back of the truck, just above the tail-lights. Cable routing is easy, reports are that reception is great.

I have also read that a 5/8 wave antenna performs better, but requires a ground plane...for example NMO mount on the roof. I have a roof rack, with an expanded steel floor. Does the expanded steel floor function as a ground plane, because if it does I could easily install an NMO mount in the middle of the rack floor, enabling me to run a 5/8 antenna.

 

[1911]

I am studying for my ham test. Going well, excited to move to that communication medium. I bought a Yeasu 2900R since it's on sale at HRO for $119 (and free shipping). I've read through a bunch of threads on here and on expo, and the obvious antenna choice is a 1/2 wave larsen whip (150B hw) mounted on the back of the truck, just above the tail-lights. Cable routing is easy, reports are that reception is great.

I have also read that a 5/8 wave antenna performs better, but requires a ground plane...for example NMO mount on the roof. I have a roof rack, with an expanded steel floor. Does the expanded steel floor function as a ground plane, because if it does I could easily install an NMO mount in the middle of the rack floor, enabling me to run a 5/8 antenna.

Good luck on your test, and good choice for your first radio - the 2900 is bullet-proof and a great 2M radio.

As far as different wavelength antennas performance, "better" is pretty relative. Since 2M is a line-of-sight band, you will get better range by being as high above the truck (including the roof) as possible. Beyond that, 1/4, 1/2, and 5/8-wave antennas have different radiation angles that may or may not suit the kind of terrain that you live in/drive on. Where you mount a 5/8 or 1/4-wave antenna (front, center of roof, back bumper, etc.) will also have more effect on the radiation pattern than on a 1/2-wave.

There is some good linked reading along these lines in this recent thread: https://forum.ih8mud.com/threads/ham-antenna-suggestions.922606/
particularly in post #13 and post #40 (both by Dragos80).

Mounting the antenna on a roof rack will still give you some or most of the ground plane from the roof, depending on if it is on the very edge of the rack or nearer the center.

Bottom line (in my experience anyway) is higher is better, and the antenna that tunes up the best (lowest SWR) at the location you decide on is the "best". If you use some version of an NMO mount, then you could borrow different antennas from friends and see which gives the lowest SWR before committing to buy one.

 

[e9999]

I use a magnet mount on the middle of the roof or roof rack, easy. I think it's a better spot than the rear.

 

[Mrtwooooo]

The roof or roof rack should be good. I've got a Larsen dual band 2m/70cm antenna mounted in my front bumper and a Larsen 5/8 wave on the roof. Both use NMO mounts so I can change them up wherever I want. I tried the 5/8 on the front bumper once and realized the performance was not that great. Probably because of the lack of ground plane. Whichever you get, get it tuned. Borrow an SWR meter or even better borrow an antenna analyzer. I had to trim my 5/8 antenna down a bit.. The Larsen should come with a little chart to get you close. The analyzer lets me set a frequency to the middle of the band and get m SWR perfect. I'm able to get great range with my 5/8 in the center of my roof.

 

[lovetoski]

Thanks MrT...appreciate the info. Attached is a pic of the floor of the rack I built.



Re the two antenna's you are using, do you use a splitter like shown in this article?

Redirect Notice

 

[Mrtwooooo]

Thanks MrT...appreciate the info. Attached is a pic of the floor of the rack I built.



Re the two antenna's you are using, do you use a splitter like shown in this article?

Redirect Notice

View attachment 1277137

yeah. the A/B switch

 

[Dirty Koala]

I have the same setup, FT2900 with Larson 150 NMO mounted directly in the middle of the roof. The reception is fantastic, but the problem is. I want to be able to mount a RTT for certain trips.

Has anyone come up with a solution to this problem? Is there an NMO extension cable that could be used to extend the cable to say the edge of the roof rack for times when the RTT is mounted?

I would prefer to not have to run another cable and would like to keep the antenna as high as possible.

 

[badlander]

I have the same setup, FT2900 with Larson 150 NMO mounted directly in the middle of the roof. The reception is fantastic, but the problem is. I want to be able to mount a RTT for certain trips.

Has anyone come up with a solution to this problem? Is there an NMO extension cable that could be used to extend the cable to say the edge of the roof rack for times when the RTT is mounted?

I would prefer to not have to run another cable and would like to keep the antenna as high as possible.

I have the same setup, FT2900 with Larson 150 NMO mounted directly in the middle of the roof. The reception is fantastic, but the problem is. I want to be able to mount a RTT for certain trips.

Has anyone come up with a solution to this problem? Is there an NMO extension cable that could be used to extend the cable to say the edge of the roof rack for times when the RTT is mounted?

I would prefer to not have to run another cable and would like to keep the antenna as high as possible.

I mounted the NMO mount to a stainless steel plate and have mounting points on the center of my roof rack and on the side of the rack, actually in the track of the Foxwing awning.. When I mount the RRT it's just a matter of relocating the plate to the side location. Extra cable gets coiled up and wire tied as needed. Takes 5 min. Easy.
Don't forget to seal up the bottom of the NMO mount with silicone sealer to protect it from the environment.

 

[Dirty Koala]

I now have a RTT but still habrnt figire out a good way to extend the NMO mount out to the edge of the rack. I dont want to just pull the nmo put of my rpof as I will have a big gaping hole. I wpuld thing there shpuld be an nmo to nmo extension that allows you to move tge antenna.

 

[LC4LIFE]

I run a Comet SBB-5 antenna mounted in the middle of my roof and it works fantastic for my radio. I picked a roof mount that has a PL-259 connector so I could extend it to the edge of the rack/roof when needed using this. I have never seen and extension for an NMO.

 

[Dirty Koala]

I run a Comet SBB-5 antenna mounted in the middle of my roof and it works fantastic for my radio. I picked a roof mount that has a PL-259 connector so I could extend it to the edge of the rack/roof when needed using this. I have never seen and extension for an NMO.

I just found this NMO to PL-259 adapter. Now to figure out the cable / mount and antenna options. Which mount did you use for the endge of the rack? Is 3' long enough to reach the edge of the rack from the center of the roof?

 

[LC4LIFE]

I just found this NMO to PL-259 adapter. Now to figure out the cable / mount and antenna options. Which mount did you use for the endge of the rack? Is 3' long enough to reach the edge of the rack from the center of the roof?

There you go...I knew those were out there but didn't connect the dots. Three feet is just long enough. I would use something like this and just clamp the rack, but remove the CB antenna adapter. If that wont work, I would look at fender mounts for CB antennas. There are tons of little brackets out there that may work for your rack. Here is the antenna I have and I really like it. Comet Sbb-5

 

[Dirty Koala]

There you go...I knew those were out there but didn't connect the dots. Three feet is just long enough. I would use something like this and just clamp the rack, but remove the CB antenna adapter. If that wont work, I would look at fender mounts for CB antennas. There are tons of little brackets out there that may work for your rack. Here is the antenna I have and I really like it. Comet Sbb-5

i think I have now ordered up everything to make it work. I picked up the same antenna that you have with the PL-259 connection. An SO-239 bulk head fitting and that mirror mount you found to mount the antenna. Coupled with a pair of 90 degree SO-239 > PL-259 elbows and a 4' cable (SO-239 > PL-259) running back to the NMO > SO-239 adapter and my problem should be resolved.

Now that the cable and antenna is all set for dual band...maybe I need to think about replacing he FT-2900 with a dual band radio.

Thanks for the help mate.

 

[LC4LIFE]

i think I have now ordered up everything to make it work. I picked up the same antenna that you have with the PL-259 connection. An SO-239 bulk head fitting and that mirror mount you found to mount the antenna. Coupled with a pair of 90 degree SO-239 > PL-259 elbows and a 4' cable (SO-239 > PL-259) running back to the NMO > SO-239 adapter and my problem should be resolved.

Now that the cable and antenna is all set for dual band...maybe I need to think about replacing he FT-2900 with a dual band radio.

Thanks for the help mate.

Right on...that sounds like it will work well.

 

[Fj81]

I have a CB mounted on my 80 series on the bumper. Should I mount my antenna for my 2m, 70cm radio away from that? Like in the rear corner, by the hatch?

 

[Skidoo]

I have a CB mounted on my 80 series on the bumper. Should I mount my antenna for my 2m, 70cm radio away from that? Like in the rear corner, by the hatch?

Center of roof would be far enough away.

 

[Fj81]

Got a Diamond Antenna and an NMO mag mount. Should be good for a while now, till I figure out how to use it and get my operator's license.

 

[Fj81]

Took the mag mount out of the box, looks beefy. The Diamond Antenna has a quick tilt feature incase you need to drop it for getting under obstacles. Like garages and such.

 

[Marine7]

Took the mag mount out of the box, looks beefy. The Diamond Antenna has a quick tilt feature incase you need to drop it for getting under obstacles. Like garages and such.
View attachment 1816451 View attachment 1816452

Sorry to “hijack” your thread, but I recently purchased a 2900 also. I found it mis-marked for $50, and figured I had better grab it before someone else does!
My question to you is- Seeing I’m BRAND new to Ham radios (heck, I can’t even program it, I’m not too tech savvy!) is there “study guides” or anything to read? I want/need to get my tech license, but from doing the “IPhone apps” Han pre tests, I NEED to do some studying! Lol Any help you could offer would be appreciated! Thanks again...Marine7

 

[Fj81]

I mainly have been chatting up the local Ham guys and people I meet. Have not done any proper studying yet! I am sure lots of other guys on here will have some good suggestions.