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Portable 60-80m wire antennas

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Bruce Nourish

Portable 60-80m wire antennas

Hi folks,

For 40m, 30m, and 20m, the KX1 docs recommend a ~24' length of
sorta-vertical #24 wire with shorter counterpoises as a good field antenna.
I've set that up for my KX1 and KX3, and (unsurprisingly) it works well on
both.

For 80m, the KX1 docs recommend a resonant antenna, and I'm considering my
options. Most of what's written out there about low band antennas seems to
be about durable (and heavy) mobile or home installations. Does anyone have
any experience they'd like to share with backpackable lower band antennas?

Options and questions I'm considering include:

* Build a coil big enough to load up my 24' vertical on 80m, with a tap for
60m. Will that be a long enough radiator?

* Figure out the kite-vertical thing, fly a wire close enough to l/4 that
the KX1 can tune it. How bulky would that be?

* Will #24 wire be a decent radiator for the lower bands, or should I eat
the (not-inconsiderable) weight of a bigger gauge?

* Does anyone have any tips on constructing backpackable (minimum weight)
coils? What's the smallest wire and lightest insulator?

* I'm planning a vertical, as this would seem to require strictly less wire
and coils than any dipole or inverted vee, but am I missing some other
offsetting advantage?

Cheers,
Bruce
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Nr4c

Re: Portable 60-80m wire antennas

I've had good luck with antennas made from RS 22 AWG Speaker wire and an Elecraft BL-2 BALUN. A 100 ft spool will yield a 135' doublet with about 30+ feet of "twinlead" feed line. You can make insulators from pieces of plastic toothbrush handles. Add a kite wonder from BuddiPole or other QRP sites and all you need is a tree for a Inverted V. It's also neat to make it an OCF by taking about 20' off one end and splicing it to the other end. Then when you put the center over a tree, the feed point is to one side.

Sent from my iPhone
...nr4c. bill

> On Mar 15, 2016, at 12:59 PM, Bruce Nourish <[hidden email]> wrote:
>
> Hi folks,
>
> For 40m, 30m, and 20m, the KX1 docs recommend a ~24' length of
> sorta-vertical #24 wire with shorter counterpoises as a good field antenna.
> I've set that up for my KX1 and KX3, and (unsurprisingly) it works well on
> both.
>
> For 80m, the KX1 docs recommend a resonant antenna, and I'm considering my
> options. Most of what's written out there about low band antennas seems to
> be about durable (and heavy) mobile or home installations. Does anyone have
> any experience they'd like to share with backpackable lower band antennas?
>
> Options and questions I'm considering include:
>
> * Build a coil big enough to load up my 24' vertical on 80m, with a tap for
> 60m. Will that be a long enough radiator?
>
> * Figure out the kite-vertical thing, fly a wire close enough to l/4 that
> the KX1 can tune it. How bulky would that be?
>
> * Will #24 wire be a decent radiator for the lower bands, or should I eat
> the (not-inconsiderable) weight of a bigger gauge?
>
> * Does anyone have any tips on constructing backpackable (minimum weight)
> coils? What's the smallest wire and lightest insulator?
>
> * I'm planning a vertical, as this would seem to require strictly less wire
> and coils than any dipole or inverted vee, but am I missing some other
> offsetting advantage?
>
> Cheers,
> Bruce
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Please help support this email list: http://www.qsl.net/donate.html
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Brian Hunt

Re: Portable 60-80m wire antennas

In reply to this post by Bruce Nourish

Hi Bruce,

Have you thought about using a 9:1 unun and about 100 ft of wire with a
short counterpoise? The unun -may- get the feed point Z down into the
range where the KX1 tuner can match it. I picked 100 ft because it's
not a quarter wave or half wave on either 80 or 60 plus and it's more
than a quarter wave on 80. You could go to 50 ft but it would be less
efficient on 80 meters.

An alternative to the unun would be to use a matching network consisting
of a link coupled tuned tank circuit. Tap the resonant coil to get both
80 and 60 and tap the link every turn for 6 - 8 turns to get close to 50
ohms. Wind the coils on a small (~1.5 inch) powered iron toroid and use
a small BC band variable cap. For under 20 watts the components would
be light weight and fit in a small plastic box.

Have fun!

Brian, K0DTJ

On 3/15/2016 09:59, Bruce Nourish wrote:
> For 80m, the KX1 docs recommend a resonant antenna, and I'm considering my
> options. Most of what's written out there about low band antennas seems to
> be about durable (and heavy) mobile or home installations. Does anyone have
> any experience they'd like to share with backpackable lower band antennas?
>
>

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K9MA

Re: Portable 60-80m wire antennas

In reply to this post by Nr4c

I've always been a fan of end-fed half wave wires for portable
operation, as they don't require a ground system, nor do they require a
balun or feedline. The inverted L configuration works well, as the high
current point is a quarter wave from the fed end. Make that as high as
you can. The horizontal part of the wire radiates much like a dipole.
It will also work, perhaps not quite as effectively, simply sloping up
from the feedpoint. Note that this is antenna NOT the same as the usual
quarter wave inverted L, which has maximum current at the feedpoint, and
works more like a vertical.

The downside is that the feedpoint impedance is very high, perhaps 2,000
Ohms, which may be beyond the range of the KX1 tuner. It is, however,
very easy to build an L network to match it. (I can provide L and C
values.) I'd also attach a couple short wires to the radio ground to
act as a counterpoise, though it may not make much difference. A couple
6 foot wires should work for 80 and above.

This kind of antenna will work on any band for which it is a multiple of
a half wavelength, though the radiation pattern will be like a long wire
at higher frequencies. On 10 and 15 meters, if you can get a half
wavelength wire nearly vertical, it will act like a half wave vertical,
which may be better for low radiation angles. I used one of those a few
years ago in the 10 Meter contest from KP2 and, in spite of a terrible
location, a bunch of people heard me.

73,

Scott K9MA

>> On Mar 15, 2016, at 12:59 PM, Bruce Nourish <[hidden email]> wrote:
>>
>> Hi folks,
>>
>> For 40m, 30m, and 20m, the KX1 docs recommend a ~24' length of
>> sorta-vertical #24 wire with shorter counterpoises as a good field antenna.
>> I've set that up for my KX1 and KX3, and (unsurprisingly) it works well on
>> both.
>>
>> For 80m, the KX1 docs recommend a resonant antenna, and I'm considering my
>> options. Most of what's written out there about low band antennas seems to
>> be about durable (and heavy) mobile or home installations. Does anyone have
>> any experience they'd like to share with backpackable lower band antennas?
>>
>> Options and questions I'm considering include:
>>
>> * Build a coil big enough to load up my 24' vertical on 80m, with a tap for
>> 60m. Will that be a long enough radiator?
>>
>> * Figure out the kite-vertical thing, fly a wire close enough to l/4 that
>> the KX1 can tune it. How bulky would that be?
>>
>> * Will #24 wire be a decent radiator for the lower bands, or should I eat
>> the (not-inconsiderable) weight of a bigger gauge?
>>
>> * Does anyone have any tips on constructing backpackable (minimum weight)
>> coils? What's the smallest wire and lightest insulator?
>>
>> * I'm planning a vertical, as this would seem to require strictly less wire
>> and coils than any dipole or inverted vee, but am I missing some other
>> offsetting advantage?
>>
>> Cheers,
>> Bruce
>> ______________________________________________________________
>>

--
Scott Ellington K9MA
Madison, Wisconsin, USA

[hidden email]

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Stephen Shearer

Re: Portable 60-80m wire antennas

In reply to this post by Bruce Nourish

I have used a G5RV (+/- 51') with ladder line using teflon 24ga silver
plated wire.
also see http://udel.edu/~mm/ham/randomWire/ ... I am working on a 9:1
and looking at the web site, a 70' wire should work fine for 80m...

73 steve WB3LGC

On 15-Mar-16 12:59 PM, Bruce Nourish wrote:

> Hi folks,
>
> For 40m, 30m, and 20m, the KX1 docs recommend a ~24' length of
> sorta-vertical #24 wire with shorter counterpoises as a good field antenna.
> I've set that up for my KX1 and KX3, and (unsurprisingly) it works well on
> both.
>
> For 80m, the KX1 docs recommend a resonant antenna, and I'm considering my
> options. Most of what's written out there about low band antennas seems to
> be about durable (and heavy) mobile or home installations. Does anyone have
> any experience they'd like to share with backpackable lower band antennas?
>
> Options and questions I'm considering include:
>
> * Build a coil big enough to load up my 24' vertical on 80m, with a tap for
> 60m. Will that be a long enough radiator?
>
> * Figure out the kite-vertical thing, fly a wire close enough to l/4 that
> the KX1 can tune it. How bulky would that be?
>
> * Will #24 wire be a decent radiator for the lower bands, or should I eat
> the (not-inconsiderable) weight of a bigger gauge?
>
> * Does anyone have any tips on constructing backpackable (minimum weight)
> coils? What's the smallest wire and lightest insulator?
>
> * I'm planning a vertical, as this would seem to require strictly less wire
> and coils than any dipole or inverted vee, but am I missing some other
> offsetting advantage?
>
> Cheers,
> Bruce
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> 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]
>

Jim Brown-10

Re: Portable 60-80m wire antennas

In reply to this post by K9MA

On Tue,3/15/2016 1:16 PM, Scott Ellington wrote:
> I've always been a fan of end-fed half wave wires for portable
> operation, as they don't require a ground system, nor do they require
> a balun or feedline.

I agree. Here's an easy way that I developed to feed one. It's an
adaptation of one that N6LF showed on his website.

http://k9yc.com/VerticalDipole.pdf

73, Jim K9YC
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Bruce Nourish

Re: Portable 60-80m wire antennas

In reply to this post by Stephen Shearer

Thanks, folks, this has been very helpful. In particular, Steve's "wire
lengths to avoid" calculator will save me a bunch of time. I've purchased a
kite and a bunch more wire, and we'll see how this goes.

On Tue, Mar 15, 2016 at 2:54 PM Ron D'Eau Claire <[hidden email]> wrote:

> The antenna efficiency drops very quickly when the radiator is made shorter
> than 1/4 wavelength or 66' on 80 meters. When end fed the efficiency of a
> short radiator is even lower depending upon the "ground" return system. The
> RF power is divided between the radiator impedance and the "ground"
> impedance, with the most power going to the higher impedance. With a short
> radiator such as a 24 foot wire, the radiator may show something in the
> order of 10 ohms while a typical "ground" will be in the range of 300 ohms
> or more, so less than 5% of the RF power actually goes to the radiator.
> Short (<1/4 wave) "counterpoises" may actually show impedances up to 600
> ohms or more, halving again the RF power going to the antenna.
>
> Note that many Hams have used such systems - a short whip on their back
> dragging a single wire on the ground behind hem for pedestrian mobile -
> with
> considerable success. That just demonstrates how little radiated power is
> required under some conditions to make good contacts. So what you
> contemplate will certainly work to some extent.
>
> I have found that the best way to load an electrically short radiator is to
> do so at the center. You can think of it as a short radiator and an equal
> length counterpoise both up in the clear. Use parallel spaced feeders to
> avoid the inherent losses in low-impedance coaxial line. Your tuner will
> need to be able to efficiently match quite low impedances in many
> situations. The Elecraft tuners use L-networks which are quite efficient
> under those conditions, as long as they can find a matching combination of
> L
> and C.
>
> Whether it's a stack of full size yagi's on a 90-foot tower or a short wire
> thrown into a tree, the compromises are always the same. It's a matter of
> doing what you can within the constraints of space, cost and time. The
> suggestions offered by Wayne in the Owner's Manuals are what he has found
> will work with the ATU with a minimum of effort. Because of space
> constraints inside the KX1 its ATU matching ranges are more limited than
> the
> KX3 or other Elecraft rigs.
>
> 73, Ron AC7AC
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of
> Stephen Shearer
> Sent: Tuesday, March 15, 2016 2:11 PM
> To: [hidden email]
> Subject: Re: [Elecraft] Portable 60-80m wire antennas
>
> I have used a G5RV (+/- 51') with ladder line using teflon 24ga silver
> plated wire.
> also see http://udel.edu/~mm/ham/randomWire/ ... I am working on a 9:1
> and
> looking at the web site, a 70' wire should work fine for 80m...
>
> 73 steve WB3LGC
>
>
> On 15-Mar-16 12:59 PM, Bruce Nourish wrote:
> > Hi folks,
> >
> > For 40m, 30m, and 20m, the KX1 docs recommend a ~24' length of
> > sorta-vertical #24 wire with shorter counterpoises as a good field
> antenna.
> > I've set that up for my KX1 and KX3, and (unsurprisingly) it works
> > well on both.
> >
> > For 80m, the KX1 docs recommend a resonant antenna, and I'm
> > considering my options. Most of what's written out there about low
> > band antennas seems to be about durable (and heavy) mobile or home
> > installations. Does anyone have any experience they'd like to share with
> backpackable lower band antennas?
> >
> > Options and questions I'm considering include:
> >
> > * Build a coil big enough to load up my 24' vertical on 80m, with a
> > tap for 60m. Will that be a long enough radiator?
> >
> > * Figure out the kite-vertical thing, fly a wire close enough to l/4
> > that the KX1 can tune it. How bulky would that be?
> >
> > * Will #24 wire be a decent radiator for the lower bands, or should I
> > eat the (not-inconsiderable) weight of a bigger gauge?
> >
> > * Does anyone have any tips on constructing backpackable (minimum
> > weight) coils? What's the smallest wire and lightest insulator?
> >
> > * I'm planning a vertical, as this would seem to require strictly less
> > wire and coils than any dipole or inverted vee, but am I missing some
> > other offsetting advantage?
> >
> > Cheers,
> > Bruce
>
>
> ______________________________________________________________
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> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>