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Antenna question

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David Beckwith

Antenna question

Just moved and my K3 needs a new antenna. My only option is to run a wire antenna over my roof--I have about 110-120 feet to play with and I can get one end up off the ground 25 feet and the center and other end about 35 feet. Any ideas? Or references to an antenna group that can help? Thanks Bunches and 73
Dave K6CGE
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James Bennett

Re: Antenna question

A doublet. Center fed with either 600 ohm or 450 ohm ladder line, a 4:1 balun close to your shack and as short a length of coax from the balun to your K3 as possible. Using a tuner (either the K3 internal or an external), you will be able to work 80 through 10 meters, and possibly six meters. This sort of antenna works GREAT.

> On Oct 17, 2014, at 1:45 PM, david beckwith <[hidden email]> wrote:
>
> Just moved and my K3 needs a new antenna. My only option is to run a wire antenna over my roof--I have about 110-120 feet to play with and I can get one end up off the ground 25 feet and the center and other end about 35 feet. Any ideas? Or references to an antenna group that can help? Thanks Bunches and 73
> Dave K6CGE
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Elecraft mailing list

Re: Antenna question

In reply to this post by David Beckwith

Alpha Delta LB-PLUS. they are tough and work great

George, W6GF

On Friday, October 17, 2014 1:45 PM, david beckwith <[hidden email]> wrote:

Just moved and my K3 needs a new antenna. My only option is to run a wire antenna over my roof--I have about 110-120 feet to play with and I can get one end up off the ground 25 feet and the center and other end about 35 feet. Any ideas? Or references to an antenna group that can help? Thanks Bunches and 73
Dave K6CGE
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Larry Gerhardstein

Re: Antenna question

In reply to this post by David Beckwith

Dave,
I have a K3 (#7360) with ATU and 347 ft. long wire 30 ft height. It
tunes up ok but performance is questionable. This same antenna performs
better with my external MFJ tuner.
Larry W7IN

On 10/17/2014 20:45, david beckwith wrote:

> Just moved and my K3 needs a new antenna. My only option is to run a wire antenna over my roof--I have about 110-120 feet to play with and I can get one end up off the ground 25 feet and the center and other end about 35 feet. Any ideas? Or references to an antenna group that can help? Thanks Bunches and 73
> Dave K6CGE
> ______________________________________________________________
> Elecraft mailing list
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>

Don Wilhelm-4

Re: Antenna question

In reply to this post by David Beckwith

Dave,

Make it a balanced dipole antenna (equal lengths on either side of the
feedpoint) for best efforts in keeping RF off the feedline. The actual
length does not matter a lot, but it should be greater than 80% of the
half wavelength for the lowest band of interest.

Use open wire line or 450 ohm ladder line to feed it down to the point
where it enters the shack - hopefully you can run the feedline
perpendicular from the radiator for at least 1/4 wavelength on the
lowest frequency of interest for lowest radiator to feedline pickup.
Put a good 1:1 current mod choke at that point. See page 29 of K9YC's
RFI tutorial http://www.audiosystemsgroup.com/RFI-Ham.pdf
for instructions on how to construct a very effective current mode choke
- note: a good balun *is* a current mode choke, but many fail to perform
as well as the ones tested by K9YC.

You will need a tuner, and any Elecraft tuner should do the job nicely.
If it does not, then you may have to make some adjustments in the length
of the parallel feedline to see if you can achieve success on all bands
of interest.

You may want to take a look at the Antenna and Transmission Line article
on my website www.w3fpr.com for a bit on non-math theory on antennas.

73,
Don W3FPR

On 10/17/2014 4:45 PM, david beckwith wrote:
> Just moved and my K3 needs a new antenna. My only option is to run a wire antenna over my roof--I have about 110-120 feet to play with and I can get one end up off the ground 25 feet and the center and other end about 35 feet. Any ideas? Or references to an antenna group that can help? Thanks Bunches and 73
> Dave K6CGE
>

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k6dgw

Re: Antenna question

Don pretty much described my low band antenna. Full Disclosure: I live
on 5 acres and have a 70' tower. That said, it is a Sloping V [I'd call
it an inverted V except is isn't resonant on any band], about 210' on a
side from the top of the tower. 450 ohm window line to the bottom of
the tower, DXE 4:1 balun, and coax into the house. I have chokes on the
coax at the balun and at the weatherhead entrance, but I've never had
any problems with RFITS [RF In The Shack] with or without the chokes.

It works well on 80-40-30, requires a tuner of course [KAT500]. Works
on 160 but warms the clouds and worms, I use an Inv-L for top band. It
also works on all the bands up from 30 but the pattern gets fairly
complex and squirts my RF in a lot of non-productive directions because
it's so big.

My experience is that an 88 ft doublet, center-fed, works really well on
40 and up in frequency, often used by those activating summits in
Summits On The Air. Shorter doublets are also effective, and not being
resonant doesn't really matter [in some cases, it helps]. Neither does
what you do with the ends. Most of the radiation comes from the center,
high current sections.

450 ohm window line is sensitive to moisture ... if you set up your
tuner for dry conditions and it's now raining, things will need retuning.

Keep in mind the wisdom of Tom, N6BT, "Anything conductive will radiate
if you get power into it."

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2015 Cal QSO Party 3-4 Oct 2015
- www.cqp.org

On 10/17/2014 3:54 PM, Don Wilhelm wrote:

> Make it a balanced dipole antenna (equal lengths on either side of the
> feedpoint) for best efforts in keeping RF off the feedline. The actual
> length does not matter a lot, but it should be greater than 80% of the
> half wavelength for the lowest band of interest.
>
> Use open wire line or 450 ohm ladder line to feed it down to the point
> where it enters the shack - hopefully you can run the feedline
> perpendicular from the radiator for at least 1/4 wavelength on the
> lowest frequency of interest for lowest radiator to feedline pickup. Put
> a good 1:1 current mod choke at that point. See page 29 of K9YC's RFI
> tutorial http://www.audiosystemsgroup.com/RFI-Ham.pdf
> for instructions on how to construct a very effective current mode choke
> - note: a good balun *is* a current mode choke, but many fail to perform
> as well as the ones tested by K9YC.
>
> You will need a tuner, and any Elecraft tuner should do the job nicely.
> If it does not, then you may have to make some adjustments in the length
> of the parallel feedline to see if you can achieve success on all bands
> of interest.
>
> You may want to take a look at the Antenna and Transmission Line article
> on my website www.w3fpr.com for a bit on non-math theory on antennas.

James Bennett

Re: Antenna question

Fred is right about the 450-ohm stuff getting funky in wet weather. Cause my tuners to do the clicky-click dance whenever it rains here, although we've been pretty dry the past few years. Because of this, I plan on replacing my 450-ohm line with 600-ohm ladder line in a couple weeks. I had the 600-ohm stuff on that doublet initially but a change in roofing materials made me change. Long story. Anyway, as you probably know, antennas work much better when built or adjusted when the weather is horrible!!!

Jim / W6JHB

> On Oct 17, 2014, at 4:57 PM, Fred Jensen <[hidden email]> wrote:
>
> Don pretty much described my low band antenna. Full Disclosure: I live on 5 acres and have a 70' tower. That said, it is a Sloping V [I'd call it an inverted V except is isn't resonant on any band], about 210' on a side from the top of the tower. 450 ohm window line to the bottom of the tower, DXE 4:1 balun, and coax into the house. I have chokes on the coax at the balun and at the weatherhead entrance, but I've never had any problems with RFITS [RF In The Shack] with or without the chokes.
>
> It works well on 80-40-30, requires a tuner of course [KAT500]. Works on 160 but warms the clouds and worms, I use an Inv-L for top band. It also works on all the bands up from 30 but the pattern gets fairly complex and squirts my RF in a lot of non-productive directions because it's so big.
>
> My experience is that an 88 ft doublet, center-fed, works really well on 40 and up in frequency, often used by those activating summits in Summits On The Air. Shorter doublets are also effective, and not being resonant doesn't really matter [in some cases, it helps]. Neither does what you do with the ends. Most of the radiation comes from the center, high current sections.
>
> 450 ohm window line is sensitive to moisture ... if you set up your tuner for dry conditions and it's now raining, things will need retuning.
>
> Keep in mind the wisdom of Tom, N6BT, "Anything conductive will radiate if you get power into it."
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the 2015 Cal QSO Party 3-4 Oct 2015
> - www.cqp.org
>
>> On 10/17/2014 3:54 PM, Don Wilhelm wrote:
>>
>> Make it a balanced dipole antenna (equal lengths on either side of the
>> feedpoint) for best efforts in keeping RF off the feedline. The actual
>> length does not matter a lot, but it should be greater than 80% of the
>> half wavelength for the lowest band of interest.
>>
>> Use open wire line or 450 ohm ladder line to feed it down to the point
>> where it enters the shack - hopefully you can run the feedline
>> perpendicular from the radiator for at least 1/4 wavelength on the
>> lowest frequency of interest for lowest radiator to feedline pickup. Put
>> a good 1:1 current mod choke at that point. See page 29 of K9YC's RFI
>> tutorial http://www.audiosystemsgroup.com/RFI-Ham.pdf
>> for instructions on how to construct a very effective current mode choke
>> - note: a good balun *is* a current mode choke, but many fail to perform
>> as well as the ones tested by K9YC.
>>
>> You will need a tuner, and any Elecraft tuner should do the job nicely.
>> If it does not, then you may have to make some adjustments in the length
>> of the parallel feedline to see if you can achieve success on all bands
>> of interest.
>>
>> You may want to take a look at the Antenna and Transmission Line article
>> on my website www.w3fpr.com for a bit on non-math theory on antennas.
>
>
> ______________________________________________________________
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> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]