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[aprssig] Helmet Antenna - dont bother.

Gerry Creager N5JXS gerry.creager at tamu.edu
Mon Mar 7 02:24:47 UTC 2005


Simply put, Rich's comments are on-target.  HT's are made the way they 
are for convenience and tradition.  That they're not the safest 
configurations in the world isn't a major concern to the radio 
manufacturers.

A.J. Farmer (AJ3U) wrote:
> When you hold an HT up to to talk, you have the antenna right in front of
> your face and close to your head.  What's the difference? 
> 
> -----Original Message-----
> From: aprssig-bounces at lists.tapr.org [mailto:aprssig-bounces at lists.tapr.org]
> On Behalf Of Rich Garcia
> Sent: Sunday, March 06, 2005 8:50 PM
> To: TAPR APRS Mailing List
> Subject: RE: [aprssig] Helmet Antenna - dont bother.
> 
> Bob... I hate to preach but let me see here you have a 1/4 wave antenna
> right at the VHF frequencies somewhere near 1/2inch or less from your head
> at 5W.
> Foil or no foil Bob please do yourself and your family a favor don't take
> the risk however small it is. I have not taught RF Safety in several years
> but take a look at some of the ARRL Tech License publications, they point
> out several things about VHF vs. Microwave and how many people are so much
> more afraid of MW than VHF and it should be the other way around.
> 
> That is not something I would be mentioning out in public. Actually for some
> time I saw a lot of geeky hard hats with BNC connectors on the top of them
> sold at hamfests, I think everyone got the message long ago since I no
> longer see them for sale.
> 
> Rich
> 
> 
> 
> -----Original Message-----
> From: aprssig-bounces at lists.tapr.org
> [mailto:aprssig-bounces at lists.tapr.org]On Behalf Of Robert Bruninga
> Sent: Sunday, March 06, 2005 7:25 PM
> To: aprssig at lists.tapr.org
> Subject: [aprssig] Helmet Antenna - dont bother.
> 
> 
> Today I was tail-bike on a marathon.
> Lesson:  Dont bother with a helmet antenna
> for voice.  (APRS maybe, but not for just voice).
> 
> I took one of those tiny 19" mag mount
> whips with a small base (like a kisses chocolate piece)
> stuck it inside the helmet protruding up through the
> air holes, covered the inside with aluminum foil and
> then let a can lid stick to the bottom of the magnet.
> 
> I also, carried an identical HT with its own
> long whip.  Conclusion was generally no difference
> after lots of side-by-side tests...
> Therefore, dont bother.
> 
> An HT held to my mouth with a similar 19" whip is
> going to work similarly as a 19" whip on the helmet at
> the same height.  I had just hoped that the slightly
> better ground  plane might work better than the HT with
> no real  counterpoise.... dont bother.
> 
> Now, for APRS where you are not holding the HT to
> your mouth, then maybe the extra height and lack
> of body blockage is worth it.
> 
> Just 2 cents...
> Bob
> 
> 
> 
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-- 
Gerry Creager -- gerry.creager at tamu.edu
Texas Mesonet -- AATLT, Texas A&M University	
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.847.8578
Page: 979.228.0173
Office: 903A Eller Bldg, TAMU, College Station, TX 77843




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