K2 + ATU + Loop antenna in the attic

[Wayne Conrad]

My radio (K2 with the internal ATU) hasn't shipped yet, but that
shouldn't stop me from putting up an antenna, right?  If only I knew
what to put up, that is.  That's where I'm asking for help.

I want to start out with an loop antenna in the attic.  Why loop? Mostly
the very American idea that more wire must be better, plus it's
balanced--I hope to not need a separate RF ground, or counterpoises, or
any of that jazz).  Why the attic?  So I don't have to worry about
lightning protection, and because it ought to be incredibly cheap to put
up.  I've spent every dime I have on the radio, you see.

The house is the usual ~60' x ~30 feet and "L" shaped, single story, and
the major axis is North/South.  The attic is full of trusses and
fiberglass, but I can get to most of it, sometimes slithering on my
belly like a snake.  There are the usual electrical wires, network
cabling (OK, maybe not everyone has CAT6 in their attic), TV coax, and
AC ducts going hither and thither.  My shingles are asphault.

I have no idea what band or bands I'll be on.  I don't even have my
license yet.

My thought is that I run the loop around the perimeter of the attic, as
close to the eaves as possible.  Over the radio bench, I'll punch a hole
in the ceiling and drop feedline down the wall.

I was thinking of open-wire feeder, because I "read on the internet"
that it might be better for this application.

It occurs to me that I could omit the 4' of feedline and just drop the
two wires down.  Using the self-adhesive conduit that the hardware store
sells, I could keep those two wires at "an appropriate distance" from
each other, and white conduit looks better against a white wall than a
black cable.  I don't know if that's a good idea, or what "an
appropriate distance" would be.

I don't know if I need a balun, or even what kind.

I don't know whether I need to keep the antenna wire off of the rafters
with insulators, or can I just let it lay there.  Nor do I know if the
answer to that question changes if I eventually go QRO.

I don't know if the length of the loop matters.

As you can tell, the ratio of things I know to things I don't know is
pretty small.  Can you please help me improve that ratio?

Thanks, and best regards,
Wayne Conrad
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[Don Wilhelm-4]

  Wayne,

I understand your reasons for putting an antenna in the attic, but that
will offer no additional lightning protection over putting it outside.

An outside antenna will pick up more noise from the house wiring, so why
go to the trouble.  Even if you mount your loop antenna on short
standoffs just above the roof (look for electric fence insulators if you
want to do that, they work very well). it will work better than it will
inside.

Your idea of just bringing the ends of the wire loop into the shack
using two pieces of conduit to maintain the spacing between the wires
will work very well - you would be creating an open wire feedline, which
is quite efficient.

You will need a balun between the coaxial output from the tuner and any
parallel transmission line.  Use a current balun.  Many use a 4:1 balun,
but in many cases (most cases), a 1:1 balun will be better.  If the
impedance at the shack end of the balanced line is low, a 4:1 balun will
make it even lower.  You might want to consider the Elecraft BL2 which
is switchable between 1:1 and 4:1 so you can choose the best ratio for
each band.

On 4/11/2011 7:11 PM, Wayne Conrad wrote:

> My radio (K2 with the internal ATU) hasn't shipped yet, but that
> shouldn't stop me from putting up an antenna, right?  If only I knew
> what to put up, that is.  That's where I'm asking for help.
>
> I want to start out with an loop antenna in the attic.  Why loop? Mostly
> the very American idea that more wire must be better, plus it's
> balanced--I hope to not need a separate RF ground, or counterpoises, or
> any of that jazz).  Why the attic?  So I don't have to worry about
> lightning protection, and because it ought to be incredibly cheap to put
> up.  I've spent every dime I have on the radio, you see.
>
> The house is the usual ~60' x ~30 feet and "L" shaped, single story, and
> the major axis is North/South.  The attic is full of trusses and
> fiberglass, but I can get to most of it, sometimes slithering on my
> belly like a snake.  There are the usual electrical wires, network
> cabling (OK, maybe not everyone has CAT6 in their attic), TV coax, and
> AC ducts going hither and thither.  My shingles are asphault.
>
> I have no idea what band or bands I'll be on.  I don't even have my
> license yet.
>
> My thought is that I run the loop around the perimeter of the attic, as
> close to the eaves as possible.  Over the radio bench, I'll punch a hole
> in the ceiling and drop feedline down the wall.
>
> I was thinking of open-wire feeder, because I "read on the internet"
> that it might be better for this application.
>
> It occurs to me that I could omit the 4' of feedline and just drop the
> two wires down.  Using the self-adhesive conduit that the hardware store
> sells, I could keep those two wires at "an appropriate distance" from
> each other, and white conduit looks better against a white wall than a
> black cable.  I don't know if that's a good idea, or what "an
> appropriate distance" would be.
>
> I don't know if I need a balun, or even what kind.
>
> I don't know whether I need to keep the antenna wire off of the rafters
> with insulators, or can I just let it lay there.  Nor do I know if the
> answer to that question changes if I eventually go QRO.
>
> I don't know if the length of the loop matters.
>
> As you can tell, the ratio of things I know to things I don't know is
> pretty small.  Can you please help me improve that ratio?
>
> Thanks, and best regards,
> Wayne Conrad
>

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[k6dgw]

On 4/11/2011 4:11 PM, Wayne Conrad wrote:

> I want to start out with an loop antenna in the attic.  Why loop? Mostly
> the very American idea that more wire must be better, plus it's
> balanced--I hope to not need a separate RF ground, or counterpoises, or
> any of that jazz).

You need a safety ground on your radio, a loop antenna does not normally
care about ground, except in what ground does to the radiation elevation
angle.

> Why the attic?  So I don't have to worry about
> lightning protection, and because it ought to be incredibly cheap to put
> up.  I've spent every dime I have on the radio, you see.

Is it the K2/10?  Anything outside will be better.  Trees?  Even
something laid over the roof will probably work better for you.
>
> I have no idea what band or bands I'll be on.  I don't even have my
> license yet.

That will be a necessity :-)
>
> My thought is that I run the loop around the perimeter of the attic, as
> close to the eaves as possible.  Over the radio bench, I'll punch a hole
> in the ceiling and drop feedline down the wall.

Elevating the wire above the ceiling joists might help some.  Many of
the "Attic Designs" that have been published seem to use the "open
space" of the attic rather than out near the eaves.
>
> I was thinking of open-wire feeder, because I "read on the internet"
> that it might be better for this application.

A balun is probably going to be important, the K2 output is inherently
unbalanced.  Since you will have the ATU, putting the balun at the radio
will eliminate any losses on the coax.
>
> It occurs to me that I could omit the 4' of feedline and just drop the
> two wires down.  Using the self-adhesive conduit that the hardware store
> sells, I could keep those two wires at "an appropriate distance" from
> each other, and white conduit looks better against a white wall than a
> black cable.  I don't know if that's a good idea, or what "an
> appropriate distance" would be.

2 or 3 cm is probably just fine.
>
> I don't know if I need a balun, or even what kind.

See above
>
> I don't know whether I need to keep the antenna wire off of the rafters
> with insulators, or can I just let it lay there.

That would be a good idea.  Electric fence insulators are cheap and
would work.

   Nor do I know if the
> answer to that question changes if I eventually go QRO.

I don't know what you mean by QRO, but if it is anything over 10 or so
watts, with such an antenna, you will likely not like the results :-)
You also need to do a radiation safety survey which you can find on the
ARRL web site.
>
> I don't know if the length of the loop matters.

Basically, you're just putting up some conductor and attempting to load
power into it.  It's a "more is better" situation.  The KAT2 will stuff
power into some pretty weird impedances, but not all possible weird ones.
>
> As you can tell, the ratio of things I know to things I don't know is
> pretty small.  Can you please help me improve that ratio?

Hope this helps.  Anything you can do outside will probably be better
than anything you can do in the attic, unless you have CC&R's.

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[Vic K2VCO]

A loop in the attic is asking for coupling to all those nearby conductors. They will do
the following:

1) Capture and dissipate your precious RF. No-one will hear you.
2) Couple large amounts of electrical noise into your receiver. You will hear nobody.
3) Pick up even QRP levels of RF and funnel it into electronic devices in your house.

The best choice is to put up a balanced 'doublet' or dipole outside. It won't be more
expensive than a loop in the attic. If you MUST put it in the attic, I still recommend a
doublet. It will couple to the wires, etc. but not as badly as a loop, which may exhibit
magnetic coupling to nearby loops of wire.

My guess is that lightning is as likely to hit a wire in the attic as one just above it
but outside! But the more likely problem with lightning is damage to the radio from
voltages induced from nearby strokes. You should make sure to have an arrangement to
dissipate static charges on whatever antenna you choose, indoor or outdoor.

On 4/11/2011 4:11 PM, Wayne Conrad wrote:

> My radio (K2 with the internal ATU) hasn't shipped yet, but that
> shouldn't stop me from putting up an antenna, right?  If only I knew
> what to put up, that is.  That's where I'm asking for help.
>
> I want to start out with an loop antenna in the attic.  Why loop? Mostly
> the very American idea that more wire must be better, plus it's
> balanced--I hope to not need a separate RF ground, or counterpoises, or
> any of that jazz).  Why the attic?  So I don't have to worry about
> lightning protection, and because it ought to be incredibly cheap to put
> up.  I've spent every dime I have on the radio, you see.
>
> The house is the usual ~60' x ~30 feet and "L" shaped, single story, and
> the major axis is North/South.  The attic is full of trusses and
> fiberglass, but I can get to most of it, sometimes slithering on my
> belly like a snake.  There are the usual electrical wires, network
> cabling (OK, maybe not everyone has CAT6 in their attic), TV coax, and
> AC ducts going hither and thither.  My shingles are asphault.
>
> I have no idea what band or bands I'll be on.  I don't even have my
> license yet.
>
> My thought is that I run the loop around the perimeter of the attic, as
> close to the eaves as possible.  Over the radio bench, I'll punch a hole
> in the ceiling and drop feedline down the wall.
>
> I was thinking of open-wire feeder, because I "read on the internet"
> that it might be better for this application.
>
> It occurs to me that I could omit the 4' of feedline and just drop the
> two wires down.  Using the self-adhesive conduit that the hardware store
> sells, I could keep those two wires at "an appropriate distance" from
> each other, and white conduit looks better against a white wall than a
> black cable.  I don't know if that's a good idea, or what "an
> appropriate distance" would be.
>
> I don't know if I need a balun, or even what kind.
>
> I don't know whether I need to keep the antenna wire off of the rafters
> with insulators, or can I just let it lay there.  Nor do I know if the
> answer to that question changes if I eventually go QRO.
>
> I don't know if the length of the loop matters.
>
> As you can tell, the ratio of things I know to things I don't know is
> pretty small.  Can you please help me improve that ratio?
>
> Thanks, and best regards,
> Wayne Conrad
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
> This list hosted by: http://www.qsl.net
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--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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[Tony Estep]

Wayne, like many members of this list, I've been right in your shoes.

Like the previous posters, I'd recommend getting your wire outside. Here's a
specific recommendation:

While waiting for your radio to come, build a 4:1 unun. Here's a website
with instructions:
http://www.pcsystems-ss.co.uk/g7lrrweb/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=52&MMN_position=77:37

I'm guessing you're on an upstairs floor, but that's okay. Run coax from
your rig to the unun. Then run a single wire out the window to the farthest,
highest tree limb you can reach (see below). This goes to the "hot" side of
the unun. For the cold side, make a counterpoise. Cut three or more wires in
various lengths from 10' to about 30' and drape them out the window, in the
gutters, on the garage roof, or whatever.

The counterpoise will be your RF ground, but you also need a good DC ground.
There's plenty of info on this reflector about that.

With the right counterpoise and a properly-built unun, your ATU will match
the wire perfectly on all the bands for which it's long enough, and you
won't have any RF in the shack.

To get a wire in the tree, you can use various gizmos. I rigged up a
slingshot to shoot a weight which pulls fishing mono from a spinning reel.
This will get a line up about 40 - 50 feet. See radioworks.com for some
advice on shooting lines into trees.

This setup sounds a bit hokey, but it works. If your wire is long enough, it
will even provide gain over a dipole. I am just one of many who have used
such an arrangement for lots of DX exploits. For example, my barefoot K3
worked 100 countries in 100 QSOs in 24 hours last month; I also have 40
zones, 300 countries, etc. etc. This is not to say that it is better than a
3-element wide-spaced Yagi, but it's a hell of a lot better than a wire in
the attic.

73,
Tony KT0NY
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[Geoffrey Mackenzie-Kennedy]

Wayne,

If you have no choice and have to use an antenna in the attic placed close
to the rafters, I would suggest that you do use iinsulators to prevent any
part of the antenna touching a rafter. A fire risk could exist if the
antenna's wire is simply laid on the rafters, especially if using higher
power on several bands.

Welcome to the hobby, and have fun!!

73,
Geoff
GM4ESD (Licensed 1946)


On April 12, 2011 at 12:11 AM, Wayne Conrad wrote:

<snip>

> I don't know whether I need to keep the antenna wire off of the rafters
> with insulators, or can I just let it lay there.  Nor do I know if the
> answer to that question changes if I eventually go QRO.


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[Michael Babineau-2]

Wayne :

You got some good advice so far.
I am in agreement that an outside antenna will perform better than one in the attic but
you can always start with an attic antenna and add an outdoor antenna later.
An attic antenna makes a great backup antenna as it will not succumb to severe weather
(i.e icing, wind etc).

As some have suggested, instead of a loop you could put up a doublet (ie dipole).
The advantage will be that it may be easier to match on a lower bands.  If you run
the wire diagonally across the attic and then bend the ends in to form a Z shape
you can probably get more wire up and that will help.

Best of luck

Michael VE3WMB

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[Wayne Conrad]

On 04/11/2011 04:11 PM, Wayne Conrad wrote:
> My radio (K2 with the internal ATU) hasn't shipped yet, but that
> shouldn't stop me from putting up an antenna, right?  If only I knew
> what to put up, that is.  That's where I'm asking for help.
> (snip)
>    

Thank you to everyone who replied, both publicly and privately.  Your
responses were great.  Most of you urged me to put the antenna outside.  
As Fred Jensen said, "Even something laid over the roof will probably
work better for you".  So, outside it will be.  I also got several
requests that I put in a proper safety ground no matter where my antenna
is, so I will do that, too.

Best Regards,
Wayne Conrad

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[Alan D. Wilcox, W3DVX]

FWIW, see my fan antenna at  
http://wilcoxengineering.com/projects/amateur-projects/39-fan-dipole
A bright idea that didn't work out so well!

Cheers, Alan

Alan D. Wilcox, W3DVX (K2-5373, K3-40)
570-321-1516
http://WilcoxEngineering.com
http://eBookEditor.net
https://www.smashwords.com/books/view/28062?ref=awilcox
Williamsport, PA 17701

On 4/15/11 1:08 PM, Wayne Conrad wrote:

> On 04/11/2011 04:11 PM, Wayne Conrad wrote:
>> My radio (K2 with the internal ATU) hasn't shipped yet, but that
>> shouldn't stop me from putting up an antenna, right?  If only I knew
>> what to put up, that is.  That's where I'm asking for help.
>> (snip)
>>
> Thank you to everyone who replied, both publicly and privately.  Your
> responses were great.  Most of you urged me to put the antenna outside.
> As Fred Jensen said, "Even something laid over the roof will probably
> work better for you".  So, outside it will be.  I also got several
> requests that I put in a proper safety ground no matter where my antenna
> is, so I will do that, too.
>
> Best Regards,
> Wayne Conrad
>
> ______________________________________________________________
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>

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[k6dgw]

On 4/15/2011 3:15 PM, Alan D. Wilcox wrote:
> FWIW, see my fan antenna at
> http://wilcoxengineering.com/projects/amateur-projects/39-fan-dipole
> A bright idea that didn't work out so well!

If I had a dollar for every "Gee, it seemed like a good idea at the
time" situation I've found myself in, I'd have a LOT more radio equipment.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2011 Cal QSO Party 1-2 Oct 2011
- www.cqp.org
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[Don Wilhelm-4]

  Alan,

Sorry to hear about your lack of success with the fan dipoles.  I have
three of them - one for 80 and 40, another for 30, 17 and 12m, and yet
another for 20, 15, and 10.  They work very well.

My "secrets" - space the wires for each band away from one another - my
80 and 40 antennas are at right angles to each other, so there is little
of any interaction.  The other two have the wires spaced about 1 foot
apart using CPVC pipe with holes drilled in them (wires through the
holes) to maintain the spacing.  PVC would work too, but is heavier).

The antennas do interact, so plan ahead, you will have to do some "cut
and try" pruning.  Tune the lowest band or resonance first, and then the
next band higher in frequency.  Trying it the other "way 'round" is an
exercise in futility (been there, done that, and have the scars).

I usually consider 3 bands on one feedline the limit of my patience, but
this last weekend I helped a friend construct an antenna with 4 wires -
80, 40, 20, and 10 meters.  It was a bit of a pain to tune, but it
worked out well.  Cut the wires at least 10% long and prune as required.

One other point - do not use separate wires for bands that are close to
the 3rd harmonic of another band - in other words, for HF, do not put a
30 meter radiator on a feedline that contains an 80 meter wire, and do
not put a 15 meter wire on a feedline that also has a 40 meter wire.  
The lower band antenna may be usable on the 3rd harmonic (likely with a
tuner), but trying to combine those two wires will result in even more
frustration.

73,
Don W3FPR

On 4/15/2011 6:15 PM, Alan D. Wilcox wrote:
> FWIW, see my fan antenna at
> http://wilcoxengineering.com/projects/amateur-projects/39-fan-dipole
> A bright idea that didn't work out so well!
>
> Cheers, Alan
>
> Alan D. Wilcox, W3DVX (K2-5373, K3-40)
>
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[AC7AC]

CONTENTS DELETED

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[Doug Person-3]

I have an array of dipoles, some trapped, some using W9INN style
chokes.  I also have a tribander.  But the antenna that gets used all
the time is 160' doublet fed with 300 ohm line which goes into a DX
Engineering 1:1 balun with short piece of RG-8 type coax coming into the
house.  The tuners on the K1, K2, and K3 will tune it to any band.  I
have experimented a great deal with fan dipoles.  They certainly work.  
And also Off-Center fed antennas; they also work well. Loops a good too.
I have a notebook with 40 years of wire antenna experiments.  For me the
most satisfying antenna so far is the simple doublet.  It will always be
the first antenna I recommend.  With the great tuners in the Elecraft
gear, it seems like a no-brainer.

73, Doug -- K0DXV

On 4/15/2011 6:16 PM, Ron D'Eau Claire wrote:

> I played with a fan dipole back in the 1960's, and played and played and
> played trying to get a decent (less than 3:1) match to 50 ohm coax. Never
> was happy.
>
> That experiment taught me the efficiency, ease and simplicity of a doublet*
> fed with open wire line. Working out the process of getting the open wire
> line into the shack wasn't nearly as difficult as trying to get the antenna
> to present a decent match to the coax, and it was a wonderfully efficient
> and effective all band antenna mounted at an "inverted V" with the apex at
> 50 feet.
>
> BTW, my doublet was 100 feet end-to-end and worked beautifully on 160
> through 10 meters. Granted, at so close to the ground the radiation was
> mostly straight up on 160 but on that band I was mostly interested in
> working locals out to 100 miles or so. We had a lot of mobiles active on 160
> back then as well as fixed stations. And none of the rude nonsense so often
> found on 75.
>
> Ron AC7AC
>
> *Wire fed at the center but not necessarily a "dipole" - i.e. 1/2 wavelength
> long - on any band.
>
> -----Original Message-----
> Subject: Re: [Elecraft] K2 + ATU + Loop antenna in the attic
>
>    Alan,
>
> Sorry to hear about your lack of success with the fan dipoles.  I have
> three of them - one for 80 and 40, another for 30, 17 and 12m, and yet
> another for 20, 15, and 10.  They work very well.
>
> My "secrets" - space the wires for each band away from one another - my
> 80 and 40 antennas are at right angles to each other, so there is little
> of any interaction.  The other two have the wires spaced about 1 foot
> apart using CPVC pipe with holes drilled in them (wires through the
> holes) to maintain the spacing.  PVC would work too, but is heavier).
>
> The antennas do interact, so plan ahead, you will have to do some "cut
> and try" pruning.  Tune the lowest band or resonance first, and then the
> next band higher in frequency.  Trying it the other "way 'round" is an
> exercise in futility (been there, done that, and have the scars).
>
> I usually consider 3 bands on one feedline the limit of my patience, but
> this last weekend I helped a friend construct an antenna with 4 wires -
> 80, 40, 20, and 10 meters.  It was a bit of a pain to tune, but it
> worked out well.  Cut the wires at least 10% long and prune as required.
>
> One other point - do not use separate wires for bands that are close to
> the 3rd harmonic of another band - in other words, for HF, do not put a
> 30 meter radiator on a feedline that contains an 80 meter wire, and do
> not put a 15 meter wire on a feedline that also has a 40 meter wire.
> The lower band antenna may be usable on the 3rd harmonic (likely with a
> tuner), but trying to combine those two wires will result in even more
> frustration.
>
> 73,
> Don W3FPR
>
> On 4/15/2011 6:15 PM, Alan D. Wilcox wrote:
>> FWIW, see my fan antenna at
>> http://wilcoxengineering.com/projects/amateur-projects/39-fan-dipole
>> A bright idea that didn't work out so well!
>>
>> Cheers, Alan
>>
>> Alan D. Wilcox, W3DVX (K2-5373, K3-40)
>>
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[Mike WA8BXN]

 
I have had two fan dipole in use maybe 15-20 years ago, before the time of
widespread use of auto tuners. One was a commercial model, with the various
lengths of wire on each side of the center insulator spaced about an inch
apart (spacers were used). I did not have so much success with it. The other
was homebrew, with 3 dipoles sharing the same center insulator and coax, but
each going in different directions with the trees available. It was a great
antenna that gave me good performance with low swr on my bands of interest
without need for a tuner.
 
Currently my most often used antenna is a dipole fed with ladder line. The
ladder line connects to a balun and a short piece of coax to the radio with
built in tuner. This setup tunes well but seems to pick up noise from the
house. I should probably use more coax to get the ladder line a bit away
from the house.
 
I also have a vertical with decent radial system, coax fed, a fair distance
from the house (>100 feet) that picks up much less noise from the house. I
do think the dipole works better than the vertical, at least for
transmitting.
73 - Mike WA8BXN
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[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Tony Estep]

On Fri, Apr 15, 2011 at 7:16 PM, Ron D'Eau Claire <[hidden email]> wrote:

> ....the efficiency, ease and simplicity of a doublet*
> fed with open wire line...
>
>
>
Ron is so right. At the risk of re-re-repeating myself, whether or not an
antenna is resonant, or matches coax, has nothing to do with its
effectiveness as a radiator or receiver of signals. You don't have to feed
it with coax. If you can put up an antenna with multiple radiators or traps
or matching sections, you can put up a single antenna with no traps and no
matching sections, feed it with ladder line or window line (or even twin
lead), and get equal (or usually better) results. I guess guys like coax-fed
antennas because they see that SO239 on the back of the rig,  but it doesn't
have to go any farther than a balun at the shack exit. Enough RF is wasted
every day in long lossy runs of coax to power a year's worth of DXpeditions.

Tony KT0NY
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[Alan D. Wilcox, W3DVX]

Don,
The fan antenna was a lashup in the attic in hopes of having another
antenna, hopefully to use with the K2 upstairs in the office. If it
worked out, great; if not, no big deal. The attic isn't easy to get into
(no pull-down), and not a lot of room to stumble around up there.

The final solution was to switch my 130' Carolina Windom between the K2
and K3. See bottom of  
http://wilcoxengineering.com/projects/amateur-projects/39-fan-dipole  .
The coax relay didn't make good contact, so I replaced it with a big 24
vdc 4PDT junk relay in a metal box: the extra contacts give solid
connections AND ground the unused feed to either the K2 or K3. BTW, only
one rig is ever physically connected to the coax unless it's powered up
and being used.

With the storms ripping around today, both the K2 and K3 are safely
disconnected!

Cheers, Alan

Alan D. Wilcox, W3DVX (K2-5373, K3-40)
570-321-1516
http://WilcoxEngineering.com
http://eBookEditor.net
https://www.smashwords.com/books/view/28062?ref=awilcox
Williamsport, PA 17701

On 4/15/11 7:29 PM, Don Wilhelm wrote:

>  Alan,
>
> Sorry to hear about your lack of success with the fan dipoles.  I have
> three of them - one for 80 and 40, another for 30, 17 and 12m, and yet
> another for 20, 15, and 10.  They work very well.
>
> My "secrets" - space the wires for each band away from one another -
> my 80 and 40 antennas are at right angles to each other, so there is
> little of any interaction.  The other two have the wires spaced about
> 1 foot apart using CPVC pipe with holes drilled in them (wires through
> the holes) to maintain the spacing.  PVC would work too, but is heavier).
>
> The antennas do interact, so plan ahead, you will have to do some "cut
> and try" pruning.  Tune the lowest band or resonance first, and then
> the next band higher in frequency.  Trying it the other "way 'round"
> is an exercise in futility (been there, done that, and have the scars).
>
> I usually consider 3 bands on one feedline the limit of my patience,
> but this last weekend I helped a friend construct an antenna with 4
> wires - 80, 40, 20, and 10 meters.  It was a bit of a pain to tune,
> but it worked out well.  Cut the wires at least 10% long and prune as
> required.
>
> One other point - do not use separate wires for bands that are close
> to the 3rd harmonic of another band - in other words, for HF, do not
> put a 30 meter radiator on a feedline that contains an 80 meter wire,
> and do not put a 15 meter wire on a feedline that also has a 40 meter
> wire.  The lower band antenna may be usable on the 3rd harmonic
> (likely with a tuner), but trying to combine those two wires will
> result in even more frustration.
>
> 73,
> Don W3FPR
>
> On 4/15/2011 6:15 PM, Alan D. Wilcox wrote:
>> FWIW, see my fan antenna at
>> http://wilcoxengineering.com/projects/amateur-projects/39-fan-dipole
>> A bright idea that didn't work out so well!
>>
>> Cheers, Alan
>>
>> Alan D. Wilcox, W3DVX (K2-5373, K3-40)
>>
>

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