Experience with 100W glass mount antennas?

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jparks29

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Looking at some Larsen 100W glass mounts...

I know that glass mounts generally suck, and especially with higher wattages, heard of glass cracking/exploding because of the heat, but is that an actual issue when tuned properly?

Anyone actually RUN 100W through a glass mount antenna? How'd it work?
 

ILMRadioMan

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When I was at the Marine Corps radio shop, at Camp Pendleton, CA, we had XTL5000s with an external PA to boost it to 100w through a glass mount antenna.

They were absolute crap. We blew numerous internal radios PAs. We had SO MANY problems with them.

Horrible idea.
 

gewecke

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This might be ok if you're only interested in keeping the snow and ice off your glass,or making sure that rf is close to your brain!:lol:
But seriously, I can't see how glass mounts are electrically efficient,except for local use only? But then I guess I haven't really done any feasible studies on performance of them either.
N9ZAS
 

zz0468

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I've used glass mount antennas and compared them with hole mounted quarter waves. What I found was, an alleged "3 db gain" glass mount performed about the same as a hole mounted quarter wave. Making some wild assumptions here, like the whip REALLY HAD 3 db gain, one could infer that there's about 3 db of loss through the glass mounted coupler. Fair enough. So, then, running 100 watts would mean there's 50 watts being dissipated somewhere in the lossy coupling. Some would go to the glass, maybe, and some wouldn't.

But in a worst case basis, do we really think 50 watts intermittently applied is enough to crack or shatter tempered auto safety glass? I don't. I doubt even 100 watts would do it, assuming ALL of the power was lost in the coupler. Maybe you could ask Mythbusters. *snicker*

As to blowing finals, the antennas are tunable, you know. I'm not a fan of glass mount antennas, but when I absolutely must use one, I take the time to tune it. I haven't hurt a radio yet, and *BONUS*, the 3 db gain ones work about as good as a quarter wave. But only after you tune 'em.
 

kc2rgw

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O.k. the obvious...

100W when you can't hear anything as it is...it's just wrong.

Punch a hole, put in an NMO mount, you won't need the 100W and you'll be able to hear as well.
 

zz0468

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O.k. the obvious...

100W when you can't hear anything as it is...it's just wrong.

Punch a hole, put in an NMO mount, you won't need the 100W and you'll be able to hear as well.
Shush. Don't confuse the issue with logic!
 

n2hbx

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100 Watts On A Glass Mount

Depends on the antenna. Our company installs glass mount disguise antennas for various "alphabet soup" agencies that run 100 watt ASTRO Spectras in both single- and dual-band configurations. We use glass mounts from Sti-Co that are designed for these applications. Haven't had an RF related failure yet. The down side is you can't just run out to the local radio emporium and pick one up, and they tend to be a bit pricey.

Personally, I wouldn't use a Larsen antenna for anything but taping cable from a decent antenna to the whip to pull it through a hole.

Larry
 
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jparks29

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O.k. the obvious...

100W when you can't hear anything as it is...it's just wrong.

Punch a hole, put in an NMO mount, you won't need the 100W and you'll be able to hear as well.
Currently have a 1/4 wave vhf nmo mount antenna...

Need lower profile.

Going with dual band fender mount antenna, ala fake am/fm radio antenna.

Currently have lo-pro UHF/800/GPS but the VHF is killing the profile...

 
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mdulrich

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When I was on the FD, our radio installers tried running a glass mount on a staff car with a 100W radio and quickly discovered that it didn't work. NMO or stay home.

Mike
 

kc2rgw

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A fake AM/FM antenna is a much better idea....much. The performance will be much better for sure vs a glass mount.

Nice property there too btw.....someday, someday.
 

k8tmk

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I used to have one, and it worked okay at 50 watts on 2 meters. Never had a problem with the glass breaking or anything like that. However, when the glass was wet, the SWR went sky high and apparently got into the car's computer. Transmitting while the glass was wet caused the engine speed to change.

Randy
 

mrweather

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You're looking for low-profile? Get a Phantom or something like that. NMO mountable and while it won't perform as well as your current 1/4 wave whip it won't suck nearly as bad as a glass mount.
 

FFPM571

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Phantoms are fine on anything but VHF. there they have such a narrow bandwith and are limited to 60watts in general every VHF have sucked. The phantom elite are a little better in VHF. The UHF and 800 elites are fine. I have a UHF on my astro saber AVA and it works great
 

Signal-Zero

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I'm running a Sti-co glass mount with a VHF Astro Spectra putting out over 100 watts. Simplex....sucks. Repeater...works just fine. Don't get me wrong,..simplex works better than a handheld inside the car. Basically I'd say it depends on your particular application.

On my previous car, I had an antenna from a company called U.S. Communications. Disguised undercover covert license plate antenna,fender,cowel,bumper antennas. It was VHF and has a coupler for your am/fm radio as well. They also make dual and tri-band. It replaces the guts from the car's own broadcast antenna from below the fender. Running the same radio...ten times better than the glass mount and it's covert.

But they are pricey....single band, your looking at around $200. The Sti-co's aren't cheap either though.
 
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