I have a Wilson 5000 Magnamount and a trunk lip mount. I was using the magnamount on the trunk and wanted to switch it to a lip mount and change the coax to lmr 240. I had the coax rewired and after installing the lip mount my swr was 19 (nineteen) on an mfj analyzer!. tried the magnamount on the trunk and got the r's to 1.7. tried a k40 magnet on the trunk and r's were flat. We cannot understand why the trunk lip mount simply refused to work. The car is a 2009 nissan altima. it was suggested by a knowledgable friend that the read window defroster sometimes causes havoc with swr's. anyway after putting the wilson mag. on the roof the r's are 1.2 i dont much care for the look of the antenna on the roof but i cannot help it now. i tried the trunk mount again last night and still the same. everything is proper, the screws are making metal to metal contact. the coax is not shorted. everything is how it should be. has anyone heard of this and might anyone have a suggestion please?
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High SWR with Wilson Trunk Lip Mount
- Thread starter iceman78
- Start date
Any of these antennas mentioned contain a finite set of parts.
If after inspecting the parts and cannot find anything wrong with it, I would suggest going with mounting the Wilsom 5000 magnet mount antenna that worked on the trunk. Tune the antenna for the best SWR you can get, and if you cannot get better than 1.5 SWR; then go with the K40 and go for the flat match.
Go with what works, be happy...
If after inspecting the parts and cannot find anything wrong with it, I would suggest going with mounting the Wilsom 5000 magnet mount antenna that worked on the trunk. Tune the antenna for the best SWR you can get, and if you cannot get better than 1.5 SWR; then go with the K40 and go for the flat match.
Go with what works, be happy...
iceman78,
Would you happen to remember the other readings from that analyzer to go with that '19' SWR? And did you try adjusting that Wilson 5000 antenna with either mount? That 1.7:1 is very close by the way.
- 'Doc
Just for your information, those trunk 'lip' mounts are typically not the 'best' in the world because of the very sharp bend the coax has to make to get around that 'lip' into the trunk. That's also something that typically doesn't 'show up' right away, usually takes a little time for that coax to do any 'migrating'. Every once in a while you run across a 'lip' mount that uses some very small coax (RG-174 for instance) to make that bend around the trunk lip. Run, don't walk, away from those things as fast as you can, they are very bad news. RG-174 and other very small cables are absolutely terrible for losses (as in inches, not 100 foot lengths). That does NOT include LMR-240, which is almost 4 times as large.
Would you happen to remember the other readings from that analyzer to go with that '19' SWR? And did you try adjusting that Wilson 5000 antenna with either mount? That 1.7:1 is very close by the way.
- 'Doc
Just for your information, those trunk 'lip' mounts are typically not the 'best' in the world because of the very sharp bend the coax has to make to get around that 'lip' into the trunk. That's also something that typically doesn't 'show up' right away, usually takes a little time for that coax to do any 'migrating'. Every once in a while you run across a 'lip' mount that uses some very small coax (RG-174 for instance) to make that bend around the trunk lip. Run, don't walk, away from those things as fast as you can, they are very bad news. RG-174 and other very small cables are absolutely terrible for losses (as in inches, not 100 foot lengths). That does NOT include LMR-240, which is almost 4 times as large.
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I ran Wilsons exclusivly when driving and found they are very very ground sensitive. It may and probably is as simple as the amount of ground each mount provides. I also had a lip mount that after running a new and seperate ground would get down near the 1:7 you spoke of. I would have quit there myself. Mike Ps. Paint doesn't ground, make sure the screws are to metal
thank you gentlement for the interesting responses. now to address them: as far as the coax bend in the trunk lip, when the lrm was installed we did not bend it for the reason you mentioned, so that part is not the problem. there was DEFINATE metal to metal contact which was verified with a continuity meter and the trunk lid itseld has 2 grounding straps from the lid to the trunk deck as well as each of the 4 doors and hood. the radio and amp themselves are grounded to the chassis too. now the weird part:
1) wilson 5K w/ trunk lip = swr of 'off the chart'.
2) wilson 5K w/ mag on trunk = swr of 1.7
3) wilson 5k w/ mag on roof = swr of 1.2
my knowledgable friend said that perhaps the read window defroster is screwing things up as far as using the trunk. everything else checks out, coax is good, grounds are good, etc. just cant figure out why i cannot use the wilson on the trunk. i always thought a trunk lip mount with metal to metal contact the the right way to go.
1) wilson 5K w/ trunk lip = swr of 'off the chart'.
2) wilson 5K w/ mag on trunk = swr of 1.7
3) wilson 5k w/ mag on roof = swr of 1.2
my knowledgable friend said that perhaps the read window defroster is screwing things up as far as using the trunk. everything else checks out, coax is good, grounds are good, etc. just cant figure out why i cannot use the wilson on the trunk. i always thought a trunk lip mount with metal to metal contact the the right way to go.
iceman78,
That's interesting. Or maybe, puzzling is a better way of saying it. A trunk mount is a nice mounting idea and would certainly be preferable to a few alternatives, I have to agree with you about that. I also have to agree with your friend, that rear window defroster could be at least part of the problem. But I have a problem believing that it would be 'off the scale' with one mount, and only a 1.7:1 with another. There's certainly more than one reason possible for that 'off the scale' reading, but two of the most common are a shorted antenna, and an open circuit to the antenna. Which is also a fairly common sort of problem when replacing the coax to a mount (or a connector, just did one'a them 'oops!' myself... oh wow, now he's 'bragging' about making mistakes).
Not that I'm doubting you, I'm really interested in how you got around that 'bending' and 'contact' thingys with the 'lip-mount'. That would certainly be handy to know. I know it depends a lot on the antenna's weight/mass, but keeping good electrical contact by using the typical set-screws is a real problem. A few times opening/closing the trunk and they usually have to be at least re-tightened. (And all things considered, we may not be talking about the same kind of 'lip' mount. The old style chromed 'tin-can' looking thingy, or one of the newer 'skeleton' looking ones?) I honestly doubt if I'll ever need one again, but who knows? Some times I get obsessed with something I can't make work. It bother's me, you know? Oh well, whatever...
- 'Doc
That's interesting. Or maybe, puzzling is a better way of saying it. A trunk mount is a nice mounting idea and would certainly be preferable to a few alternatives, I have to agree with you about that. I also have to agree with your friend, that rear window defroster could be at least part of the problem. But I have a problem believing that it would be 'off the scale' with one mount, and only a 1.7:1 with another. There's certainly more than one reason possible for that 'off the scale' reading, but two of the most common are a shorted antenna, and an open circuit to the antenna. Which is also a fairly common sort of problem when replacing the coax to a mount (or a connector, just did one'a them 'oops!' myself... oh wow, now he's 'bragging' about making mistakes).
Not that I'm doubting you, I'm really interested in how you got around that 'bending' and 'contact' thingys with the 'lip-mount'. That would certainly be handy to know. I know it depends a lot on the antenna's weight/mass, but keeping good electrical contact by using the typical set-screws is a real problem. A few times opening/closing the trunk and they usually have to be at least re-tightened. (And all things considered, we may not be talking about the same kind of 'lip' mount. The old style chromed 'tin-can' looking thingy, or one of the newer 'skeleton' looking ones?) I honestly doubt if I'll ever need one again, but who knows? Some times I get obsessed with something I can't make work. It bother's me, you know? Oh well, whatever...
- 'Doc
Hi Doc...and yes puzzling is the better word. I can say that the coax is not shorted because i tested everything with the meter and all is as it is supposed to be. as far as the trunk lip mount it is the soda can looking one...the typical wilson one, we got around the sharp bend by simply not bending the coax. the hole on the mount where you would normally make the bend we didnt, just ran the coax straight through the hole and into the trunk. the fella who did the wiring is officially considered around here to be the 'wire guy'. he's the man for coax and he builds antennas. very knowledgable man. he was dumbfouded by this and offered up the notion that the defroster might be the culprit. just seems too odd that the mag on the trunk yields 1.7 swr and with the trunk lip the r's max out the meter.
Take the Wilson on the roof with the 1.2 match. My Wilson does the same thing on my roof. Just watch for low trees!
That should work, go with it...
That should work, go with it...
I also recently had the exact same experience switching from a W5000 magmount to the trunk mount. Magmount swr was flat, trunk mount was 3:1, antennas were placed in exactly the same location on the trunk lid. Lid has braided straps going to body, good metal to metal contact all around. Wilson's website says that a 3:1 swr with a trunk lip mount indicates a grounding issue and they recommend running a short ground strap from the mount to a solid metal contact point. I plan on trying that running braid to a point on the underlid bracing with good contact. When time permits...
wilsons seem to like being placed at the highest point of your vehicle
which is your roof.and thats also the best place toput a antenna
id use the magnetmount wilson and forget it
which is your roof.and thats also the best place toput a antenna
id use the magnetmount wilson and forget it
It sounds to me like the screws on the trunk lip mount just aren't providing enough of a ground path from whatever contact they're making with the metal in the trunk. You can verify this by running some ground strap from one of the screws to another ground point.
just for the heck of it i am going to try re-grounding out the trunk. while i did verify metal-to-metal contact from the wilson's screws to the chassis with a meter maybe the path simply isnt good enough. i'm going to re-strap the trunk lid itself and also run a strap from the set screw to the chassis. if all that doesnt help the swr issue i am going to blame the rear defroster and forget the whole thing. part that bothers me most is that i just had LMR 240 put into the trunk mount and now i cant use it.
tried running straps from the set screw itself directly to the chassis--no help. someone suggested that the trunk on the altima is aluminum. didnt think that should make a difference though as the magnet works on the trunk. my buddy has a chrysler 300 which has an aluminum trunk and his wilson trunk lip mount worked just fine. magent will stay on the roof
That's is where I have my Wilson 1000. On a 2007 Honda CR-V, with a Galaxy DX99V and a handheld D104/M6. The first time I ever talked barefoot skip in the mobile was with this setup - just two weeks ago.
Wilson antenna + radio + operator + roof mount = it works!
