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Re: LF:Ice and frost on 600m antenna

To: <[email protected]>
Subject: Re: LF:Ice and frost on 600m antenna
From: "mal hamilton" <[email protected]>
Date: Tue, 12 Jan 2010 14:25:05 -0000
References: <[email protected]>
Reply-to: [email protected]
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Pete
I use 1.5mm insulated multi strand wire normally but sometimes 2.5mm but since it is insulated the WX seems to have little effect on it.This is the 1/4 wave inv L TX antenna.Other antennas here use the same type of wire and again the WX has little effect.
My radials are also insulated 2.5 mm.
Bare copper wire might be more vunerable to WX changes.
de mal/g3kev
 
----- Original Message -----
From: M0FMT
Sent: Tuesday, January 12, 2010 1:51 PM
Subject: LF:Ice and frost on 600m antenna


Hi LF Group

 

In an attempt to calculating the effect of ICE (Haw frost) on my antenna I get these results.

With a wire diameter of 1.5mm flex weave, it comes out to 1.1 amps for 60 watts RF applied. This is confirmed crudely by observing a pair of car festoon lamps (12Vx0.5A each) in parallel in the antenna up lead glowing to full brightness.

With an estimated increase in antenna wire diameter to 10mm caused by the Haw frost I did not notice any change in antenna current by this method.

Running the calculation through using a 10mm wire I get 1.2 amps and again to an absurd size of 20mm diameter there is virtually no increase in current.

 

The recent WX at this location has had no noticeable effect on the antenna. If it did I would suspect leakage through a dodgy insulator at the top of the inverted “L” up lead.

The type I use is a deeply ribbed glass insulator about 8 inches long.


73 es GL petefmt


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