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Author Topic: 50-watts UHF Mobile ~ Exposure?  (Read 831 times)
N1RIK
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« on: August 04, 2006, 05:27:47 PM »

I just ordered a new Icom IC-208H for the car, and I'm going to be putting my Tram 1180 mobile antenna on a trunk lip mount on the back of the car.  With this configuration with my antenna on the back, will it be too much RF exposure for me to run 50-watts on UHF in the car??
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W3LK
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« Reply #1 on: August 04, 2006, 07:27:17 PM »

Don't worry about it. You'd have to be sitting on the trunk keying the rig to get any appreciable exposure.

If this were a problem, there would be no mobile installations. Smiley

73,

Lon - W3LK
Baltimore, Maryland
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N1RIK
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« Reply #2 on: August 05, 2006, 06:43:11 AM »

I suppose your right.  I was looking at the distance between the trunk and my seat and I was thinking it was only about 10 ft maybe.  I've always used magmounts on the roof before, however, I'm going to a more better cosmetic approach.  With all the antics I've done with RF (ooops), I'm sure I'll be ok on this.  I might get a taller antenna.  My Tram is only about 37 inches tall.  I hope the 50-watts helps me better in fringe areas on my local repeater (cause there's a lot of fringe areas around on it lol).  73s ~ Bill
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W3LK
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« Reply #3 on: August 05, 2006, 01:35:00 PM »

Bill:

You are worrying needlessly. Unless you are standing right next to the antenna and transmitting a steady carrier for ten or fifteen minutes you will have no problem. Proof of this is the FCC doesn't require exposure test for mobile installations, even FM ones.

Law enforcement and other services have been running 100w on VHF and UHF for years.

FWIW, the height of the antenna will have virtually no effect on radiation exposure and the 'super' antennas are a waste of money in most situations. A Larsen NMO270C is still the best performing antenna for the money around.

I know you like the Trams, but I have heard of too many instances of the loading coil in the middle of the whip melting for me to ever spend the money on one.

Good Luck with the installation.

73,

Lon - W3LK
Baltimore, Maryland
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N1RIK
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« Reply #4 on: August 06, 2006, 09:34:08 AM »

Really!  I had a Lakeview mobile antenna that was identical to my Tram and my centerload ended up becoming "pregnant" which worried me.  I purchased the Tram in leu of paying s/h for sending the Lakeview too and from the company seeing the Tram was half the price of the Lakeview and the same thing.  It's been performing well, however I haven't put a SWR meter on it (mainly cause the only one I own is the HF one in my 706mkiig lol).  Maybe I'll put my friend's MFJ Annalyzer on it.  Hopefully it won't have a problem taking 50-watts of UHF.  So far the most RF on UHF I put through it has been 20-watts.  Thanks for the heads up. 73s ~ Bill
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W3LK
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« Reply #5 on: August 06, 2006, 01:20:36 PM »

I'm referring to the VHF/UHF models, not HF. Smiley

Lon
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N1RIK
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« Reply #6 on: August 06, 2006, 02:20:50 PM »

Yeah, I had a Lakview Dual Band antenna that is IDENTICALLY in every way to my Tram 1180 EXCEPT the sticker doesn't say Lakeview, it says Tram.  When I bought the Tram, it said the max power rating was 75-watts, so I should be ok.  I looked on the reviews and saw one had toasted the antenna by running a 75-watt 2m mobile on it.  I think I will be fine, but I defently want to change my SWR.  I might swing by HRO when I go up to NH on vacation next month.  73s ~ Bill
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K5LXP
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« Reply #7 on: August 06, 2006, 06:40:01 PM »

Odds are good that the SWR will be fine.  The real test is to put 50 watts into it for a minute or so, then see how hot the coil gets.  I've seen some go from vertical to 45 degrees after the center matching section went soft from the heat.

Mark K5LXP
Albuquerque, NM
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N1RIK
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« Reply #8 on: August 06, 2006, 07:02:32 PM »

Well, I run my 706mkiig at full power on 2m often.  I assume it's putting out around 50-watts, although I haven't put a wattmeter on it.  So, this is a semi-common problem I take it !?  I've seen the antenna gets a lot of good reviews, however I had my earlier mishap with it (The one with the Lakeview sticker), it was partly bent over by a few degrees.  I wonder who really makes the antenna, because the Lakeview and Tram look identical right down to the luggs holding on the center-load ?
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N1RIK
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« Reply #9 on: August 06, 2006, 07:03:59 PM »

Well, I run my 706mkiig at full power on 2m often.  I assume it's putting out around 50-watts, although I haven't put a wattmeter on it.  So, this is a semi-common problem I take it !?  I've seen the antenna gets a lot of good reviews, however I had my earlier mishap with it (The one with the Lakeview sticker), it was partly bent over by a few degrees.  I wonder who really makes the antenna, because the Lakeview and Tram look identical right down to the luggs holding on the center-load ?
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N1RIK
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« Reply #10 on: August 07, 2006, 03:16:27 PM »

You know what?  I checked the center-load of my antenna today, and it looked pregnant!!! I'm mad.  I'm ordering a new antenna tonight! ~ Bill
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W3LK
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« Reply #11 on: August 07, 2006, 04:08:00 PM »

Get a Larsen NMO270B and you'll never need to but another 2m/440 antenna.

Sorry you got your tram pregnant!!! Smiley

73,

Lon - W3LK
Baltimore, Maryland
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W3LK
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« Reply #12 on: August 07, 2006, 04:09:00 PM »

Make that BUY another ...

73,

Lon - W3LK
Baltimore, Maryland
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N1RIK
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« Reply #13 on: August 07, 2006, 04:49:52 PM »

I just got of the Univeral Radio website.  I just ordered a Larsen 270C.  I hope this does the trick Smiley ~ Bill
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W3LK
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« Reply #14 on: August 07, 2006, 07:51:01 PM »

Bill:

Call 'em back and get the B version. The difference is the C version is chrome and has an enclosed coil in the middle of the whip. The B version is black and has an open coil. It's just about indestructable, although the C is good, too. I just don't like the closed coil. Smiley

73,

Lon - W3LK
Baltimore, Maryland
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