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ke4pym
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join:2004-07-24
Charlotte, NC
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Through-the-glass antennas

Looks like, after 2 years of looking, I'm getting a new car. I've settled on the Subaru Outback.

Also thinking this might be a good time to finally get a mobile rig. Due to how high the car is and how low my garage is, a through-the-glass antenna will have to be used.

Looking at primarily just 2m, maybe 440. Can anyone recommend (from personal experience) a good antenna?

Hamfest is next weekend. Time to buy!


mr weather
Premium
join:2002-02-27
Mississauga, ON

I've never used it (I'm a drill-the-NMO-kind-of-guy) but the only one I've heard that is any good is the Larsen 2/440 glass mount.
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UHF
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reply to ke4pym

I've used the MFJ antennas. They work. In my experience it worked almost as well as a 1/4 2m antenna hole mounted. But it took a LOT of tweaking to tune the antenna, using a network analyzer. It wasn't even close to a match when I started, but got it down to about 1.2 SWR on 2m.

Another option is a fender mount. Cheap and easy.


ke4pym
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said by UHF:

I've used the MFJ antennas. They work. In my experience it worked almost as well as a 1/4 2m antenna hole mounted. But it took a LOT of tweaking to tune the antenna, using a network analyzer. It wasn't even close to a match when I started, but got it down to about 1.2 SWR on 2m.

Another option is a fender mount. Cheap and easy.

Fender as like the jobbie that mounts to the inside of the engine compartment fender?

That might work. Would look weird. But might work. I don't have access to a network analyzer. How would one tune the antenna in that instance?


aSic
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join:2001-05-17
Wakulla, FL
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1 edit
reply to ke4pym

Seems like this question comes up regularly.

PYM: since you're settling on an Outback, check out this thread from 2008 with pics from my thru-glass installation on my old Outback.

»mobile antenna for 2m/70cm

I thought I also posted pics of my "fender mount" Comet CP5M on the same car...but I cant seem to find them. Whatever... the CP5M has enough adjustments to be installed on the steep angles of the hatch lid on the Outback. I had mine installed drivers side, about 2" from the curve from vertical to horizontal bottom on the hatch. The low mounting made plenty of room for the tall Comet SB15 6/2/440 antenna I was sporting on that car after I realized that thru-the-glass is too much of a compromise.

Comet CP5M: »www.universal-radio.com/catalog/···863.html
Comet SB15: »www.universal-radio.com/catalog/···167.html

edit: Found a photo on my notebook of the tail end of the car. Pic was taken after my exhaust mods, but you can see my antennas.




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ke4pym
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Thanks aSic.

Not long after I posted here, this thread popped up over at the Outback forum:

»www.subaruoutback.org/forums/104···ack.html

I'm keenly interested in those hatch mounts. But I need to do some measuring to make sure the antenna will fit without banging on the garage door. I have a strange feeling it won't.

Also, need to settle on a radio. Probably before I buy the mount(s).



SmokChsr
Who let the magic smoke out?
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join:2006-03-17
Saint Augustine, FL
reply to ke4pym

Then there's my option on a Tahoe, i use a dual band mag mount on the roof and if I go under something too low, slap, it falls over on the roof. Of course if you had to stop to put it back up every time you pull out of the garage it might get a bit old.


ke4pym
Premium
join:2004-07-24
Charlotte, NC

Thanks SmokChsr. I currently have a mag mount and only use it on a temporary basis. I find mag mounts left for very long to damage the paint. Even with a so-called paint protector mat under them.



GeekNJ
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reply to ke4pym

I know Diamond makes a motorized mount such as »www.diamondantenna.net/k9000tm.html or »www.diamondantenna.net/k9000lrm.html

Maybe other manufacturers do too. I know some folks that commute to NYC and use parking garages use them without a problem - as long as they remember to lower them
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mattmag
Premium,ExMod 2000-03
join:2000-04-09
NW Illinois
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reply to ke4pym



I've had good luck with thru-glass antennas for VHF use. I prefer Larsen Antennas, but I have also used Antenna Specialists with similar results. There can be issues with deeply-tinted glass, as some of those applications use a metallic powder in the glass which obviously causes coupling problems.

Tuning is important, as mentioned. I use a Bird wattmeter to get it set as close to ideal as possible, but you won't ever see a perfect match thru-glass.



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reply to ke4pym

said by ke4pym:

Thanks SmokChsr. I currently have a mag mount and only use it on a temporary basis. I find mag mounts left for very long to damage the paint. Even with a so-called paint protector mat under them.

Exactly. Plus they become missiles in a crash. I had a horrible time with RF getting into the electrical system of my car years ago. Turned out that throwing away the mag mount and hole mounting the antenna solved it. Antennas need a ground, and mag mounts ain't grounded.

ke4pym
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said by UHF:

Antennas need a ground, and mag mounts ain't grounded.

I've been thinking about this as well.

Let's say I get super duper radio 4250. And I put the main radio under, say, the driver's seat. And I run power cable (pos + neg) to the radio and use break out boxes for power.

Could I run a ground cable from the antenna to the neg break out box for grounding?

I've read people having a terrible time finding a good grounding point on the Outback. I figure, if I'm going to have to tear the car apart to put the super duper radio 4250 in, I might as well ground the antenna this way - if it is acceptable.


mb

join:2000-07-23
Washington, NJ
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3 edits
reply to UHF

said by UHF:

Antennas need a ground, and mag mounts ain't grounded.

That would be an RF ground, not a DC ground. A mag mounted antenna properly placed that can "see" a good ground plane can be an efficient radiator depending more on the antenna's design and operating frequency. Stray RF is due to inefficient radiation.


UHF
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Correct. But a mag mount still does not provide an efficient RF ground, among all the other downfalls of them. Same exact Larson antenna that gave me fits with the magnet mount worked excellent with the NMO hole mount. When it comes to 2m/440 antennas, if you're going to use a mag mount, you're better off just drilling a freaking hole. It takes 15 minutes to do it right instead of half-assed. If you can take the time to run power from the battery, why would cut corners and slap a magnet mount on the roof instead of doing it right?

The ONLY time I use a mag mount is for temporary use. I've been known to use glass mounts, but only because the sun roof was in the way of installing a real antenna.



SmokChsr
Who let the magic smoke out?
Premium
join:2006-03-17
Saint Augustine, FL

said by UHF:

Correct. But a mag mount still does not provide an efficient RF ground, among all the other downfalls of them.

I likely would have hole mounted by now, except that the mag mount is working so perfectly! My current Tahoe does have a sunroof so my mounting locations are limited. Not to mention that every so often I need to carry "stuff" on the roof rack. Having mag mounts makes it easy to relocate as necessary to accommodate. As far as the RF ground goes it works just fine, the key being you have to make sure the radio itself has a good RF ground. Keep in mind it is the radio that is the RF generator.

In your case I would suspect that the radio had a poor RF ground, or you had a damaged shield in the coax.

I'm well aware that a good NMO mount can't be beat, but I've been unable to find any degradation with my mag mount install. I've got plenty of NMO mounts in the shop should I want to change, but for my application I'm quite happy doing it this way.

I'm not sure what all these other downfalls are your speaking of, the only downfall I've observed is that it just doesn't look pretty. As a radio tech, I would have noticed and RF deficiencies. Now would I recommend mag mounts for a customer.. Hell no.. but for myself!!

PS. this is the same mag mount antenna that I removed from my previous Tahoe that got hit in the rear by a vehicle doing about 100 on the interstate. Surprisingly, it stayed right there didn't even fall over. When it comes to projectiles I'm more worried about those inside the vehicle than on the roof. In a real crash the antenna is the least of the projectile concerns.


Radio Active
My pappy's a pistol
Premium
join:2003-01-31
Fullerton, CA
reply to ke4pym

said by ke4pym:

Looks like, after 2 years of looking, I'm getting a new car. I've settled on the Subaru Outback.

Also thinking this might be a good time to finally get a mobile rig. Due to how high the car is and how low my garage is, a through-the-glass antenna will have to be used.

Looking at primarily just 2m, maybe 440. Can anyone recommend (from personal experience) a good antenna?

Hamfest is next weekend. Time to buy!

Glass antennas (antennae?) are for suckers. I'd recommend against. All they do is warm the glass.

Poke a hole in your vehicle and mount a righteous 17" whip.

Also, check out »k0bg.com/
Alan Applegate has some great tips.

EDIT: Before you do anything, check this page... »k0bg.com/options.html
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reply to SmokChsr

said by SmokChsr:

In your case I would suspect that the radio had a poor RF ground, or you had a damaged shield in the coax.

That could be. I bought the mag mount and radio at an estate sale a few weeks after I got licensed way back when I was in high school. At that point I didn't know a lot about radio so other than checking the SWR I didn't have a clue.

If the Tahoe is like my Blazer was, hole mounting with a sun roof is a problem. They have those ridges in the roof so you have to mount it off center. I ended up using a glass mount, which worked pretty well. I had a problem with "good" antennas here due to intermod from a Channel 2 TV station and a local FM station. It was one of the few times were a better antenna was actually worse since it made the intermod worse. Didn't help that I was less than 3 miles from both of the broadcast transmitters. The Ch2 station has since gone off the air. I was always going to put a high pass filter on the rig to eliminate the intermod, but I was able to work the repeater I wanted just fine with the glass mount, so I didn't get around to it.


mitchell

join:2002-06-21
Darlington, SC
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reply to ke4pym

I've found that Glass Mount antenna at VHF (two meters) is a compromise at best. With the glass on many vehicles being reflective or tinted (many times with bits of metal embedded) in the very area you want to mount the base, it just does not work well. It may work close in, but not optimally....

Many Radio shops will check your preferred mounting location with a capacitance meter and will let you know if that location is a good spot.

BTW, if you do use a on glass unit check the outside base every so often to ensure the base sticky is still holding good...(or you'll be buying a new antenna) Tessco, Inc sells re-mount kits (and antennas too)...



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said by mitchell:

BTW, if you do use a on glass unit check the outside base every so often to ensure the base sticky is still holding good...(or you'll be buying a new antenna)

If it's not holding good, you installed it wrong. Period. The glass has to be CLEAN (as does the tape, don't peel the backing until you are ready to stick it on), and it helps if it's warm. Never install on cold glass. I always do the outside portion first so I can see if there's an air bubble trapped under the adhesive tape. I installed hundreds when I worked doing mobile installs and never once had one comeback. The reinstall kits are in case you purposely need to remove and reinstall.


fifty nine

join:2002-09-25
Sussex, NJ
kudos:2
reply to ke4pym

Glass mount antennas are a bad idea in general. Today's car glass has defroster wires and antennas in it which will mess up your signal.

Bite the bullet and drill the hole.


ke4pym
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said by fifty nine:

Glass mount antennas are a bad idea in general. Today's car glass has defroster wires and antennas in it which will mess up your signal.

Bite the bullet and drill the hole.

I'll drive around with my HT or no radio at all before I drill a hole. That isn't going to happen. Period.

I've found a mount that will probably work. But I need to measure the clearance between the car and the garage door. Otherwise, I may be putting the antenna on the lip of the hood if I go through with this project.

Ruled out the glass antenna.


mitchell

join:2002-06-21
Darlington, SC

Probably the best in the long run. Good luck with finding a solution. The Diamond/Comet lip mounts are really nice with the thin coax for the rubber seal portion...

Let us know what you end with....



fifty nine

join:2002-09-25
Sussex, NJ
kudos:2
reply to ke4pym

said by ke4pym:

I've found a mount that will probably work. But I need to measure the clearance between the car and the garage door. Otherwise, I may be putting the antenna on the lip of the hood if I go through with this project.

Certainly much better than a through glass antenna. They're doing all sorts of stuff with the glass these days.


Ender3rd

join:2001-07-15
Connecticut
reply to ke4pym

Click for full size
NMO Mount
I have used a Larsen 220 MHz through-glass antenna for the past 12 years and it works fairly well. However, it does not compare favorably to a 1/4 wave antenna installed in my NMO mount, so that should tell you something.

Have you considered an NMO mount installed under the lip of the Outback's rear hatch? I did that with a 2002 Subaru Outback and it worked great. I now use the same mount on my Jeep with excellent results on 6M, 2M, and 440 MHz. To establish a good RF ground I did drill one small hole under the hatch overlap but nothing is visible on the exterior of the vehicle. It works much better than my through-the-glass mount and I can still drive into the garage without any contact between the antenna and the garage door.

Whatever you decide, good luck with the new installation!
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