[Hallicrafters] Snow / Antenna question.

[Bill Gerhold]

The question was as follows: "Will transmitting on 40 m at about
100 watts do any warming of the antenna and remove the snow?"

To which my answer and the others was "No".  The VSWR going "Way Up" does
not contribute to heat build up.  As another reply stated, heating of the
antenna is something that should be avoided since it is wasted power.  VSWR
going "Way UP', just means the antenna "System" needs to be retuned or
adjusted.

This has nothing to do with melting snow on "ANY" antenna using RF.  As to
your "Ice Belt" statement, I'm at 1200 feet here in NNJ and we just had an
ice storm that brought down trees and power lines.  All my antennas were
about twice as thick as normal up to and including 900 MHz without any ill
effects except the SWR.  The SWR on my 80-meter dipole fed with ladder line
changed quite a bit but a simple adjustment of the tuner and it was fine.
Running 1.5kw did not start a rain storm.

The absorption of RF by snow or ice is negligible.

K2WH

----Original Message-----
From: jeremy-ca [mailto:km1h at jeremy.mv.com] 
Sent: Saturday, February 02, 2008 7:04 PM
To: Bill Gerhold; hallicrafters at mailman.qth.net
Subject: Re: [Hallicrafters] Snow / Antenna question.

Try telling that to anyone who has had HF yagis ice up. The VSWR goes WAY up

until the sun melts the ice. Its no fun when it happens during a contest! 
Since these antennas are quite narrow band the effect is dramatic.

I and anyone else in the ice belt has experienced it. Light snow just 
sitting on the elements has no effect.

VHF/UHF high performance yagis are designed so that the bandwidth is wide 
enough so that they arent detuned in plain old rain. They become rotary 
dummy loads when iced up.

Carl
KM1H



----- Original Message ----- 
From: "Bill Gerhold" <k2wh at optonline.net>
To: <hallicrafters at mailman.qth.net>
Sent: Saturday, February 02, 2008 4:41 PM
Subject: RE: [Hallicrafters] Snow / Antenna question.


> No.  Snow or ice is virtually invisible to RF unless it has minerals or 
> salt
> in it.  Other than that, it's not there.
>
> K2WH
>
> -----Original Message-----
> From: hallicrafters-bounces at mailman.qth.net
> [mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of Waldo Magnuson
> Sent: Saturday, February 02, 2008 11:51 AM
> To: hallicrafters at mailman.qth.net
> Cc: Waldo Magnuson
> Subject: [Hallicrafters] Snow / Antenna question.
>
> Spokane, WA has been getting a lot of snow this winter (about 70 inches
> so far) and yesterday my horizontal 40 m dipole had about 2 or 3 inches
> piled up on it (and it did sag a little).  My transmitter is currently
> undergoing some repair so I couldn't check but I know some of you will
> know the answer to this question.  Will transmitting on 40 m at about
> 100 watts do any warming of the antenna and remove the snow?  Thanks.
> 73,  Skip  W7WGM
>
> ______________________________________________________________
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