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Author Topic: Magnet Mounts....Just how safe are they????  (Read 16045 times)
N6AJR
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« Reply #30 on: December 07, 2011, 11:04:03 AM »

Another trick you can do is pick up a spare rear trunk lid that matches your car, and drill and mount as many antennas as will fit on the lid.  when you sell the car, put the "real" trunk lid back on.

Bye the way, if you use a trunk lip mount ( like the diamond  K 400 C) it needs to go on the "sides" of the trunk lip, not the back near the rear window. These are strong mounts  when mounted with the load sideways, but when mounted on the back of the trunk lid they will bend the lip.  they are made to go on the side.
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AE6ZW
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« Reply #31 on: December 07, 2011, 10:36:13 PM »

I use 5 inch magnetic mount ( MFJ or High Sierra antenna ) , they seems to hold 5/8 wave 2 meter ANT  much better than smaller magnetic mount, which it came with 5/8 2 mtr antenna.
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KB2FCV
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« Reply #32 on: December 08, 2011, 10:02:50 PM »

I haven't used a mag mount for well over a decade, I drill mine. The last two cars I've had I drilled them the day I picked them up from the dealer.

Sure, some mag mounts might hold ok when driving but what happens if you're involved in an accident and that mag mount is suddenly now a missile?
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W8JX
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« Reply #33 on: December 09, 2011, 12:43:22 PM »

Sure, some mag mounts might hold ok when driving but what happens if you're involved in an accident and that mag mount is suddenly now a missile?

If you get in that big of a wreck the antenna is the least of your worries.
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AI4HO
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« Reply #34 on: December 11, 2011, 05:50:31 PM »

I have used and will continue to use mag mounts when and where I think appropriate.  I used to use nothing but mag mounts..big small, 1- 5" magnet or 4- 5" magnets, didn't make any difference.  Since I bought my 2011 Toyota Tundra, 4X4 double cab, I have not used any until about a month ago.  My lip mount that I had on the hood of my truck is without an antenna.  Until I can get another antenna I have a dual band mag mount on the roof as a temporary setup until I find an appropriate antenna for my truck.  I have my Tar Heel HP-40 now mounted in the bed of my truck, where as when I had my 09 Ranger, it wasn't the case.  Being as I had a cap over the bed, and effectively negating the bed as a source to mount my Tar Heel.  I had already had a big 4 magnet mount I bought from Robert at Tar Heel, he had produced several of these huge mounts made for the HP-40A, and the "Stubby" Tar Heel antenna.  I mounted this beast on the roof of my truck..well back, and within inches of the roof of the cap covering the bed.  This system worked well for the entire 2 and a half years I had my Ranger. 

Never once, did I ever have one of my mag mounts "fly" off, I have seen them come off from friends who had mag mounts on their vehicles.  Once, while riding with a friend who has mag mounts we were going at a pretty decent clip, he hit the breaks for a light that changed..really fast, I wound up with a bunch of coax and this mag mount with the antenna attached almost in my lap.  Once stopped, we pulled off, I got out to see why this mount came off so easily, I visually inspected everything on and around this mount.  Found some moisture under the mount, and on the roof, wiped all parts down, made sure there was NO moisture on or under this mount.  We then proceeded onward to our destination without further incident.  Moisture is definitely not a good thing for a mag mount, if any gets in under around a mag mount, it can definitely turn that mild mannered mag mount into a ballistic missile.  I would check my mounts on a weekly basis, making sure there was no moisture, grit, anything that could cause that magnet to loose contact with the surface under it.  I also used magnet covers, or whatever they are called, it covers the magnets bottom, usually has the center cut out..looks sorta like a donut. This protects the vehicles roof surface from scratches and what not, if you're using a mag mount these are a life saver for your vehicle.

I believe, that if one properly places the mag mount checks to make sure  that there is no moisture, or grit anywhere on or under the magnet.  I had been in 2 or 3 accidents..none of which were my fault.  Two were in the area of my kids high school, and I was traveling at less than 20 MPH, the other one..an elderly gentleman pulled in front of my Ford Sport Trac when I had it.  I was traveling at 45 MPH, guy pulls slap in front of me..I had zero time to evade this car and T boned his 90-91 Plymouth, with my 03 Sport Trac, my big 4 magnet mount I had at the time slid forward an inch, maybe an inch and a half, the edges of the mount scratched a bit of the paint on the roof, but the mount held firm.  I think mag mounts serve a purpose, there are time when nothing but a mag mount will do, these days, my use of mag mounts are limited only by circumstances.  I will use them again, no doubt, but for now, my little dual band mag mount is all I need at present.  I still have my big 4 magnet mount I bought for my Tar Heel HP-40A, haven't decided weather or not to sell it, as it is still usable, just needs a good cleaning and lube the bolts the magnets are attached, use my wire wheel, get rid of a little rust build up and it is good to go. 

Any way..thank you all very much for taking the time to read my post, Merry Christmas to one and all who celebrate this joyous time of year.  May y'all get what ya want, want what ya get, I pray that 2012 is a Happy, healthy,but above all a safe New Year.

73 de Mark
W3LZK
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K1CJS
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« Reply #35 on: December 15, 2011, 09:08:29 PM »

...If you use a magnet mount, I can almost guarantee it will scratch up the paint on the surface.  I've yet to see where it hasn't.  I've traded in vehicles with residual antenna holes that I plugged with rubber plugs or installed a cell phone antenna, and I've never heard a word mentioned about them.  I once traded in vehicle with scratches from a mag mount, they dropped the value $500 to allegedly repaint the roof.

For me, the safety factor is why I will not use a magnet mount...  

That last line says it all.  The safety factor should be the one thing that would preclude the use of magnet mounts on a moving vehicle.  No matter how many miles someone claims to have travelled with no issues, there is always tomorrow.  And tomorrow may well prove to be the day that something DOES happen--even to someone who thinks they're safe because nothing ever happened to them.

I can also attest to the paint issues that are mentioned in the first paragraph.  I had the use of a company car where I used a magmount, and I had to get it repaired where the magmount had damaged the paint--or I had to pay up front when turning it in. 

Magmounts certainly are convenient--but is that convenience worth someones life?  I think not.
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KX5F
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« Reply #36 on: December 16, 2011, 05:45:12 AM »

Went to a Hamfest last month and my brother-in-law was following in his car, I loaned him a 1/4 wave and a brand new Larsen mag-mount so we could talk back and forth on the trip.   Everything worked fine until we got back and he went to remove the mag-mount,  the whole thing came apart from the magnet, just broke, and this was a Brand New Larsen mag-mount.  It was a good thing it was only a 1/4 wave Larsen antenna, as anything larger would have been lost.   Lost my trust in mag-mounts after that.      Patrick   kx5f
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W8JX
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« Reply #37 on: December 16, 2011, 06:20:36 AM »

...If you use a magnet mount, I can almost guarantee it will scratch up the paint on the surface.  I've yet to see where it hasn't.  I've traded in vehicles with residual antenna holes that I plugged with rubber plugs or installed a cell phone antenna, and I've never heard a word mentioned about them.  I once traded in vehicle with scratches from a mag mount, they dropped the value $500 to allegedly repaint the roof.

For me, the safety factor is why I will not use a magnet mount...  

That last line says it all.  The safety factor should be the one thing that would preclude the use of magnet mounts on a moving vehicle.  No matter how many miles someone claims to have travelled with no issues, there is always tomorrow.  And tomorrow may well prove to be the day that something DOES happen--even to someone who thinks they're safe because nothing ever happened to them.

What last line says is I do not know how to use PROPER magnet size for antenna in question, not that concept is unsafe. Use CORRECTLY sized magnets and you will have no problems.


I can also attest to the paint issues that are mentioned in the first paragraph.  I had the use of a company car where I used a magmount, and I had to get it repaired where the magmount had damaged the paint--or I had to pay up front when turning it in.  

Improperly sized magnet will walk on car over time and damage paint some. With a properly sized magnet it will not walk. I use over-sized magnet mounts with a thin vinyl pad on them and problem is minimal.

Magmounts certainly are convenient--but is that convenience worth someones life?  I think not.

I want you to find one time were someone was killed by these magic flying magnets. You have a better chance of killing someone from a mistake you make driving than from a magnet mount on your car. Are you going to stop driving too to "save a life"?
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K0BG
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« Reply #38 on: December 16, 2011, 06:33:14 AM »

Justifying using a mag mount by comparisons to the size or the number of the magnets borders on inanity. First of all, one would have to know the exact capacitive reactance of any specific mag mount. That's a bit difficult to measure, and calculating same will only get you close. Whatever the capacitance, there will be some resistive component, and that resistive component will add ground loss.

Over the years, this subject has been beat so badly, the remains almost no longer exist. Perhaps folks should spend some time on Danny Richardson's, K6MHE, web site.
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K3GM
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« Reply #39 on: December 16, 2011, 08:22:12 AM »

I'll forget the "flying missle" argument for now.  After my Larsen Magmount/6m Hamstick incident on the Jersey Turnpike (see previous post on page 1), I went out and purchased a 4 mondo magnet Opec NMO mount to secure the 6m hamstick for temporary operations.  Have you ever tried to get one of those things off the roof of a big SUV when you're standing on a step ladder off to the side of the darn thing!  It's damn near impossible to do it without compromising the finish.  So now I've got a third NMO hole installed in the roof of my Tahoe for my 6m weak signal hamstick, and a 4 magnet NMO mount for the flea market table out at  Dayton this year.  Flying missles aside, mag mounts sooner or later damage the paint finish.
« Last Edit: December 16, 2011, 08:27:00 AM by K3GM » Logged
W8JX
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« Reply #40 on: December 16, 2011, 09:32:39 AM »

Flying missles aside, mag mounts sooner or later damage the paint finish.

Sooner or later car is going to wear out too. The bigger the magnet, the less it will walk on body and scratch paint. They should be removed for time to time and cleaned to get dirt and moisture than build up under them and re-wax surface or car where magnet sits before replacing it.
« Last Edit: December 16, 2011, 10:20:11 AM by W8JX » Logged

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W6ZPC
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« Reply #41 on: December 17, 2011, 05:58:09 AM »

Back in my, dare I say it, CB days, I had a mag mount antenna with a center loading coil on it. The only time it came off was when I passed a semi coming the other way and his wind gust knocked it off the roof. It never came off otherwise. I now have a two meter quarter on the roof and the only time it came off was when there was two inches of ice on the roof and it partially melted and slid off the roof, taking the mag mount and antenna with it. Like a previous poster, the antenna slid down the driver's side door and ended up sticking out horizontally from the door.
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K1CJS
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« Reply #42 on: December 20, 2011, 06:22:12 AM »

Since my last post here seems to have disappeared, I will say only this.  There are those who think they have all the answers but are sadly lacking in the practicality/safety departments.  It's a shame that those people insist on pushing their ideas as correct while recommending them to others--and causing those others to ignore the consequences of cutting corners and doing things the easy way.  I wish those people who push their ideas would get a taste of suffering the consequences of those ideas--the consequences that others have suffered or will suffer in following them.
« Last Edit: December 20, 2011, 06:27:02 AM by K1CJS » Logged
W8JX
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« Reply #43 on: December 21, 2011, 09:31:12 AM »

Since my last post here seems to have disappeared, I will say only this.  There are those who think they have all the answers but are sadly lacking in the practicality/safety departments.  It's a shame that those people insist on pushing their ideas as correct while recommending them to others--and causing those others to ignore the consequences of cutting corners and doing things the easy way.  I wish those people who push their ideas would get a taste of suffering the consequences of those ideas--the consequences that others have suffered or will suffer in following them.

And then there are those that preach gloom and doom and yet cannot site one incident of a magic flying magnet hurting someone or someone being sued over it. Point is if you PROPERLY size magnet(s) to antenna you will not have any problem but some have trouble grasping this. Most magnets that come standard with antennas that include them are not up to job.  This is where some misconceptions about magnet mounts come from.
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K0BG
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« Reply #44 on: December 21, 2011, 10:07:37 AM »

John, I agree with Chris.

Anyone can justify anything they wish. Some maligned people even justify murder. But whatever you personally justify, is not prima facie for the rest of us.

It isn't whether they stay put or not, scratch or moon the paint, or never fly off, or whatever justification you wish to use. For me, it is the loss in efficiency, and the common mode issues which go along with using mag mounts. Those are factors you cannot justify even if they do not affect your installation. Dispute as you see fit, but the mobile cognoscenti know better.
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