[TowerTalk] Inspecting or even de-icing antennas from the ground

Thu Dec 8 08:43:11 PST 2011

NAA at Cutler ME, transmitting on 14.7 KHz to submarines so the RF would
penetrate the water a few scores of feet, in winter, would periodically
stop the CW broadcast, and a sloppy hand key would send "QRX - DEICING"
and they'd go key down for 3-5 minutes with their multiple megawatts to
heat the elements and melt the ice.  Yes, they used towers for antenna
supports, for MILES of wire in the air, added for relevance of this post.

Merrilly Christmas,

Barry Merrill W5GN, EI/W5GN

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of K1TTT
Sent: Thursday, December 08, 2011 10:30 AM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Inspecting or even de-icing antennas from the
ground

I use a telescope for inspection, does pretty good except you have to move
it around the tower to see all sides of some things.  

As far as shaking off ice, forget it... ice forms on the antennas because it
sticks hard!  The only time that may have any effect is when it is just at
freezing or there is enough sun to melt the interface from aluminum to ice,
and then rotating the antenna or shaking a guy wire may have enough effect
to break it loose.  But just a degree or two colder and it just won't let
go.  I have seen ice hold on for days of wind that were flapping the
elements all over the place... small chunks break off but most of it would
remain in place.  Take a look at some of the pictures from the telescope at:

http://wiki.k1ttt.net/2011%20Maintenance%20and%20Upgrade%20Blog.ashx#jan_19_
ice
http://wiki.k1ttt.net/2011%20Maintenance%20and%20Upgrade%20Blog.ashx#novice
On the November 24'th pictures the ice has been on the antennas for 24 hours
and is cracked but still mostly there.  It didn't finally come off till
after dark when the temperature went up above freezing.   

Click on the pictures for the full size image to see all the details.  Like
this one of the bottom 40m antenna:
http://www.k1ttt.net/images/2011_nov_23_ice_0009.jpg

David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net

-----Original Message-----
From: Jim Lux [mailto:jimlux at earthlink.net]
Sent: Thursday, December 08, 2011 16:10
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Inspecting or even de-icing antennas from the
ground

On 12/8/11 7:58 AM, John W wrote:
>
> Santa is bringing my nephew a radio controlled helicopter for 
> Christmas. It has a camera built in, with 4 GB of memory.
>
> It just occurred to me that being able to fly a camera up to the top 
> of a tower could be a handy way to inspect to see if something is 
> broken or amiss without having to climb. It also occurred to me that 
> perhaps one could suspend some sort of a loop under the helicopter 
> and, if it's highly maneuverable, maybe even use it to gently shake an 
> element that has got ice building up on it, as a way of maybe knocking 
> some ice off.

Photography yes, manipulation of elements, much, much trickier.

It's hard to tell from a distance, but the position control tolerance of
most R/C flyers isn't all that wonderful.  Not that it can't be done, but
it's pretty hard.  Little bits of air turbulence, etc. The things move
around a lot more than it seems from the ground.

There's also a sort of problem that the helos with good
autopilot/stabilizers tend to be more expensive than ones that don't.
There are really high performance ones used in things like film shoots with
gyrostabilized cameras and VERY good autopilots.  They're in the many
kilobuck range, though. A blade strike on an antenna element with any of the
R/C helicopters is almost certainly going to be an expensive episode.

However, technology is ever improving.  My Parrot AR-Drone toy is remarkably
stable (although hard to use in any amount of breeze outdoors).  You could
easily use the onboard camera to fly it along an element to look at stuff.
It's light weight enough that if you did get a blade strike and it plummets
out of the sky, it would probably not get too damaged (and there is repair
insurance available for it, as well), and it probably wouldn't break
anything else on the way down.

>
> Wondering if anyone has ever considered using a RC helicopter for this 
> purpose, and wanted to throw the idea out there as a suggestion in 
> case it hasn't been tried yet. I plan to give it a try. I assume a 
> telescope, or at least a good pair of image-stabilized binoculars, 
> would need to be used by the pilot, in order to be able to see exactly 
> what you're doing from the ground.

A good pilot with a good machine could probably do it 100 ft away without
too much trouble without binoculars.

What I want is a R/C flyer with enough range and speed to do far field
patterns of HF antennas...
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