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Date: | Thu, 2 May 2013 21:45:01 -0600 |
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Hello Ian, Perhaps you know this but if you twist your feedline about one
turn every 0.5 meters the wind will not blow it around so much. I have
built probably ten dipoles over the years and good luck. 73
Ed K7UC
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From: "Ian Westerland" <[log in to unmask]>
Sent: Thursday, May 02, 2013 9:11 PM
To: <[log in to unmask]>
Subject: Re: Doublet Antenna
> Hi Colin. It is a centre fed di pole with open wire feed line
> instead of coax. So you have the centre insulator witht the 2 wires
> which you can have as a flat top or inverted v. The length depends
> on what you want and how much space you have to fit it in.
>
> Mine is an inverted v configuration cut for 3.58 Megahertz
> 65.4 feet long, or 19.92 meters.
>
> The feed line which is the tricky part of the aerial is 30.4 meters
> or 102 feet long hanging down as close as possible to 90 degrees from
> the wires.
>
> This comes down to a 4:1 balun, into about 1 meter of RG-213 coax
> into the LDG KT-100 tuner.
>
> There is a lot of interesting and helpful information on the internet
> if you type into your search engine, "Doublet antenna" including a
> very helpful chart with recommended feed line lengths for 80 and 40
> meters. It also shows how some lengths of feed line are to be
> avoided. The recommended feed line lengths are in green and the ones
> to be avoided are in red.
>
> Hope that helps. Stay in touch and hopefully we will have a QSO one
> day. I hear some good signals from Canada regularly at night.
>
>
> 73
>
>
> Ian, VK3vin
>
>
>
> At 12:49 PM 3/05/2013, you wrote:
>>can you describe the basic design and construction of the antenna?
>>IE element length and feedline length?
>>I've never experimented with a doubllet style and wouldn't mind trying it.
>>
>>73
>>Colin, V A6BKX
>>----- Original Message -----
>>From: "Ian Westerland" <[log in to unmask]>
>>To: <[log in to unmask]>
>>Sent: Thursday, May 02, 2013 8:28 PM
>>Subject: Doublet Antenna
>>
>>
>> > Hello to all on the list. Someone posted a question about doublet
>> > antennas a couple of days ago and i have just made one for multi band
>> > operation between 80 and 10 meters. It has been a challenge but the
>> > results so far are really better than I thought they would be.
>> >
>> > The antenna is cut for a low frequency of 3.58 megahertz in our 80
>> > meter band, fed with 300 Ohm feed line, through a 4:1 balun into an
>> > LDG TK-100 tuner. The results on 80 meters are the best I have had
>> > from any antenna used so far including the standard coaxial fed
>> > dipole although there seems no real reason why this should be the
>> > case. Maybe it is the lower loss feed line doing the job.
>> >
>> > I have encountered problems on 40 meters that seem to be related to
>> > the length of the feed line but results are improving with a little
>> > fine tuning and experimentation with feed line length. The doublet
>> > is 9 meteres off the ground at present, but during next week it will
>> > be raised by another 3 meters so it will be 12 meters or 40 feet at its
>> > apex.
>> >
>> > I will post to the list again on the doublet when I complete the
>> > project but at present, even though it is not at its optimum, I am
>> > more than happy with its performance on both transmit and receive.
>> >
>> > Ian Westerland, VK3vin
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