Shorter whip in Wilson base?

[ClemsonSCJ]

I’ve got a Wilson magnet 5000 roof mounted antenna on my Grand Cherokee. I’m wanting to do 2 things. One is I’m wanting to get rid of the magnet mount and get something that’s more permanently mounted towards the “centerish” of the roof. I had to mount the magnet antenna at the very back of the roof because the roof of my SUV has ridges that done allow the magnet to sit flat and achieve a good ground, and therefore it was causing super high SWR. I’m looking at going to the Wilson 1000 roof mounted antenna.

The 2nd thing I’m wanting to do is shorten the whip. The 62” whip that comes with the magnet antenna and also the Wilson 1000 I’m planning on going to is just long enough to catch stuff I drive through on a regular basis. The breezeway of my kids’ school is pretty damn high but my antenna still catches it and sometimes it’s enough to cause the whip to swing just right and knock the magnet off the roof of my Jeep. Obviously the longer the antenna, the more efficient the antenna. But will putting a shorter whip kill the performance if I go to something like a 49” or 36”? Thanks for any input.

 

[hill]

You could switch to this NMO Larsen antenna, but still around 52". Can drill a hole for the mount in the center roof and will likely work better than your mag mount. Plus this antenna will outlast your Wilson and even your vehicle.

LARSEN ANTENNAS NMO27C Larsen 27-30 MHz Mobile Whip Antennas | DX Engineering

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[prcguy]

If your asking about shortening the whip on the Wilson, its tuned with a specific length and if you change that its no longer a CB antenna. You could heat and bend the whip 90deg at the height you need like 36" or even shorter so the top portion points backwards. That will not hurt performance much and should still tune up ok. Most of the radiation is from the lower portion of the antenna anyway.

I’ve got a Wilson magnet 5000 roof mounted antenna on my Grand Cherokee. I’m wanting to do 2 things. One is I’m wanting to get rid of the magnet mount and get something that’s more permanently mounted towards the “centerish” of the roof. I had to mount the magnet antenna at the very back of the roof because the roof of my SUV has ridges that done allow the magnet to sit flat and achieve a good ground, and therefore it was causing super high SWR. I’m looking at going to the Wilson 1000 roof mounted antenna.

The 2nd thing I’m wanting to do is shorten the whip. The 62” whip that comes with the magnet antenna and also the Wilson 1000 I’m planning on going to is just long enough to catch stuff I drive through on a regular basis. The breezeway of my kids’ school is pretty damn high but my antenna still catches it and sometimes it’s enough to cause the whip to swing just right and knock the magnet off the roof of my Jeep. Obviously the longer the antenna, the more efficient the antenna. But will putting a shorter whip kill the performance if I go to something like a 49” or 36”? Thanks for any input.

 

[ClemsonSCJ]

If your asking about shortening the whip on the Wilson, its tuned with a specific length and if you change that its no longer a CB antenna. You could heat and bend the whip 90deg at the height you need like 36" or even shorter so the top portion points backwards. That will not hurt performance much and should still tune up ok. Most of the radiation is from the lower portion of the antenna anyway.

I had no idea you could do that, so that’s good to know. However I don’t need to shorten it by much. Most everything I hit is only catching the top 6 inches so if I can do something about a foot or so shorter I should be good.

You could switch to this NMO Larsen antenna, but still around 52". Can drill a hole for the mount in the center roof and will likely work better than your mag mount. Plus this antenna will outlast your Wilson and even your vehicle.

LARSEN ANTENNAS NMO27C Larsen 27-30 MHz Mobile Whip Antennas | DX Engineering

Free Shipping - Larsen 27-30 MHz Mobile Whip Antennas with qualifying orders of $99. Shop Mobile Whip Antennas at DX Engineering.

www.dxengineering.com

Thanks for the suggestion. It’s funny, I’ve been using Wilsons since I was in high school and haven’t really considered using another brand.

 

[prcguy]

It sounds like a crazy thing to do but it works. I would place the whip in a vice and have a steel shank maybe 1/4" dia ready then heat the whip right at the vice jaws and when cherry red bend it carefully and quickly over the round shank so you get a nice little bend radius. After its bent to your satisfaction heat the same spot cherry red then quench quickly in oil if you have it or water should be ok. That will heat treat the bend so its not too soft and droop in the future.

I had no idea you could do that, so that’s good to know. However I don’t need to shorten it by much. Most everything I hit is only catching the top 6 inches so if I can do something about a foot or so shorter I should be good.

Thanks for the suggestion. It’s funny, I’ve been using Wilsons since I was in high school and haven’t really considered using another brand.

 

[davidgcet]

as someone that has installed thousands of antennas, let me say DO NOT roof mount a cb whip antenna. when it catches something right, and eventually it will, it will peel back your roof and require a body shop to fix it.

also, even though you think cutting 6" to a foot is not much, that is actually changing the tuning drastically and will kill any performance gain a hard mount gives you.

 

[ClemsonSCJ]

as someone that has installed thousands of antennas, let me say DO NOT roof mount a cb whip antenna. when it catches something right, and eventually it will, it will peel back your roof and require a body shop to fix it.

also, even though you think cutting 6" to a foot is not much, that is actually changing the tuning drastically and will kill any performance gain a hard mount gives you.

Well if you’re saying not to roof mount and everyone else is saying not to magnet mount (which I can’t really do anyways efficiently), what other options do I have?

 

[mmckenna]

Well if you’re saying not to roof mount and everyone else is saying not to magnet mount (which I can’t really do anyways efficiently), what other options do I have?

You're fine with the roof mount. I've done permanent NMO installs on all my trucks since the late 80's, never had one 'peel back the roof' and never seen that happen on any of the vehicles at work. I've used the Larsen NMO-27 on many trucks, including the aluminum body F-150's and never had an issue. I have an F-350 with a stiff VHF antenna on the top and got forced through a Las Vegas parking garage with about 3" to spare above the roof line. The base spring took a permanent bend, but no damage to the roof.
To keep the antenna from getting stuck on something, make sure it's got the little ball on the end. If it does get stuck, it will pull the NMO mount out, I've seen that happen once, and it slightly deformed the sheet metal, but I was able to bend it back and reattach the mount. No tearing of metal. Not saying it's not possible, but I've never seen it happen in 30 years of doing this. There are thousand and thousands of public safety vehicles out there running around with antennas mounted on the roof.

 

[iMONITOR]

Automatic Car Wash Destroys Aluminum F-150 Antenna

https://www.ford-trucks.com/articles/automatic-car-wash-destroys-aluminum-f-150-antenna/

 

[jonwienke]

as someone that has installed thousands of antennas, let me say DO NOT roof mount a cb whip antenna. when it catches something right, and eventually it will, it will peel back your roof and require a body shop to fix it.

Not if the mount is installed correctly.

And only if you install a heavy fiberglass whip without the proper spring at the base.

A Wilson antenna uses a thin stainless whip that will bend or break long before the mount tears loose if installed correctly. And yes, that is exactly what I have installed on my truck, in the center of the cab roof.

 

[iMONITOR]

The sheet metal on new vehicles these days is really thin! My very first car (1952 Ford) back in 1966 had sheet metal so thick and heavy you could mount a Rohn 20 ft tower on the roof!

 

[prcguy]

The tensile strength of steel is much higher than aluminum and that would not have happened on any other vehicle.

Automatic Car Wash Destroys Aluminum F-150 Antenna

https://www.ford-trucks.com/articles/automatic-car-wash-destroys-aluminum-f-150-antenna/

View attachment 96784

 

[mmckenna]

Automatic Car Wash Destroys Aluminum F-150 Antenna

I'd honestly hope that people that were smart enough to put an NMO on the roof of their truck would also be smart enough to not drive through a car wash with the antenna still on the roof. This is exactly why NMO rain caps were invented.

 

[davidgcet]

ive seen it plenty of times, sometimes you get lucky and the nmo ears break so the hole can be beat back down and reused. but I have also personally had to move mounts where the roof was so jacked up they had to bondo it. yes center of roof is best for performance, but it is also highest risk for damage. springs may or may not help, some springs are so stiff the rod itself will bend before the spring does(antennex was bad about this). Larsen coils generally break apart themselves before the roof will.

as far as people being smart enough to remove an antenna before going thru a car wash, have you met very many people??? some will if told just once, others will rip one every couple weeks and never understand why. we used to have one ambulance locally that the whole plate on top of the box had to be replaced because they have ripped it so many times pulling in to sonic. the pull in to a stall nor the bending of the antenna hurt it, it was backing up with the antenna bent into the overhang where it would catch and pull ripping the mount right up thru the plate. same driver almost every time, and his was excuse was he didn't know it would do that. LITERALLY he did it at least once a month.....

 

[Ab9kw]

Wilson use to sell a shorter whip that had a loading coil in the middle. I'm not sure if it is still available.

 

[FiveFilter]

The thin metals on today's cars are very susceptible to dents, dings and tears. Bolting an antenna on tightly that won't break-away itself can easily damage the metal it's attached to, especially if put on the least-supported part, the middle of the roof. I've heard that some folks apply backing plates of some sort beneath the antenna base, but I don't know how well that works. I guess it "depends."

Personally, I use mag-based antennas, and remove them when not needed. They range from the 35-inch Lil Wil, to 56-inch Wilson 500 to 62-inch Wilson 1000. On my Mazda sedan I tend to use the shorter models because it goes in garages, and on my F250 I use the longer models when towing the travel trailer, and on my Jeep offroad I use the intermediate size in brush etc.

 

[jonwienke]

That's why God invented springs and washers. Choose a spring that will flex before the sheet metal tears, and if the metal is thin, reinforce the underside with a washer or a small metal plate between the sheet metal and the mount base. If bending the antenna down rips the mount loose, your installation is incompetent. There's zero excuse for an install that tears loose the first time you bump into a tree branch or whatever.

 

[slowmover]

Permanent-mount “damage” is a non-issue.
Just do it right.

Adjusting or removing for obstacles is just part of it. SIRIO line has some that will adjust nicely. Then move it back. The performance trade-off not worth a shorter antenna, IMO.

A low clearance bridge, yeah, I stop traffic to remove mine on the Pete. Hustler Quick Disconnects on Wilson 2000s till yesterday. Pop right off.

Heat & bend sounds like fun to try.

 

[ClemsonSCJ]

So I think I have come up with a better solution. I remembered I had a 4ft K40 Superflex antenna in the garage that would perform as well as I need it to. My plan in my mind was to put an NMO mount in the corner of my hood near the regular radio antenna, and just use a NMO to 3/8-24 adapter. But the hood has a bit of an outward angle so it would put my antenna at a goofy, awkward angle towards the outside of the vehicle. If I were using a metal whip it wouldn’t be that big of a deal cause I could just bend it at the base to face straight up, but in this case I can’t do that with a fiberglass antenna.

So what I think I’ve decided to do is an NMO near the back of the roof and do the same adapter there. The only dilemma now is figuring out whether I want a spring at the bottom of it. The antenna itself has a decent bit of flex, and with it being about a foot and some change shorter than my Wilson whip, I’m thinking it would get caught on very little and it would likely flex enough to keep from hurting anything. I looked at some videos of the heavy duty spring and it seems to make the antenna wobble too much, and I’m worried it would be even more exaggerated being on the roof and getting “slingshot” in every direction every time I hit a little hump.

Anybody have any input on this idea of what might work?

 

[mmckenna]

Anybody have any input on this idea of what might work?

I don't recommend it.
The NMO mounts are designed for flexible whips. Putting an NMO to 3/8 x 24 adapter on there, plus a spring, plus a thick fiberglass whip, probably will put too much strain on the whole setup.

If you must use a 3/8 x 24 thread antenna, you'd probably do better with something designed for it and mounted off the bed rail.

Or, just get the Larsen NMO-27 and put the NMO mount on the roof.