Elecraft

Antennas for K1 field use

Classic

List

Threaded

10 messages Options

g3yiq

Antennas for K1 field use

I agree that random wires and fishing poles are as good as most
antennas in the field but a PAC12, or homebrew version of the same,
needs no other supports and is compact and light. It's an ideal beach
antenna, where salt water helps minimise ground losses, and I've had
plenty of transatlantic QSOs with the PAC12 and 3W from a K1 and KX1.
At least for these circumstances, it's a good compromise. Beaches tend
to be short of trees!

73 Bob G3YIQ
______________________________________________________________
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

Mike Morrow-3

Re: Antennas for K1 Field Use

Frank/KD8FIP wrote:

> Seems like there are two ways to go. Buddistick vs.
> PAC12................or random wire with Elecraft T1.

That would be very inaccurate. HF vertical antennas for field use will almost
*never* have a proper and effective ground system. Add to that the losses
of loading coils/traps, and one will very certainly find *at least* a 30 dB difference,
receiving and transmitting, in side-by-side comparisons between the vertical and
any simple wire resonant dipole. That means six S-units. That means a one watt
signal into the dipole will be better than 1000 watts into the vertical!

The installation of a semi-effective ground system for the vertical would require
multiple tuned counterpoise wires that are far more troublesome to employ than
just using a simple resonant dipole. The dipole requires *no* grounding system.
For operation in that very rare environment in which there is nothing to support
the ends of the dipole, I've used two wooden mop handles and some cord with
tent stakes as guys for the poles.

I always use a resonant wire dipole, with in-line insulators and jumpers in each
leg that can be connected to resonate for any ham band from 40 to 10 meters,
inclusive. It's cheap (less than $25, typically), very light-weight, and easy to roll
up and pack away. Even when used on 40m at only eight feet above ground, it
grossly exceeds the performance of even the most expensive "field" vertical.
(I can send a pdf file with measurments and other details, on request.)

Mike / KK5F
______________________________________________________________
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

K7TV

Re: Antennas for K1 Field Use

Verticals can be very efficient with just one elevated radial.
Of course, such an antenna can be viewed as a dipole, so yes, dipoles are
good!
Is it better to have one leg of the dipole horizontal at 8 ft or vertical?
My experience is that on dry and rocky ground horizontal is usually better,
but only by a little, and not by anything close to 30 dB.
There are also big differences in performance depending on distance and skip
angle etc, so the vertical can sometimes work better for an individual path.
Where the ground is wet with salt water I believe the vertical configuration
will win by a good margin (I have no personal experience though), and many
real-life situations may fall somewhere in between.
A good loading coil doesn't affect efficiency much as long as the antenna
leg is shortened by less than 50%. On the upper bands it is rather easy to
avoid loading coils altogether, either in homebrew configurations or using
the extension rods offered by the commercial makers. However, if a
horizontal dipole leg is shortened by a coil, it is still the same height.
If a vertical is shortened, it will have less average height, giving it
further disadvantage versus the horizontal, but again subject to great
variations depending on the surroundings and propagation path. It doesn't
hurt to have the capability to set up alternative configurations to find out
what works best in a given situation.

73,
Erik K7TV

----- Original Message -----
From: "Mike Morrow" <[hidden email]>
To: <[hidden email]>
Cc: <[hidden email]>
Sent: Sunday, July 12, 2009 7:19 PM
Subject: Re: [Elecraft] Antennas for K1 Field Use

> That would be very inaccurate. HF vertical antennas for field use will
> almost
> *never* have a proper and effective ground system. Add to that the losses
> of loading coils/traps, and one will very certainly find *at least* a 30
> dB difference,
> receiving and transmitting, in side-by-side comparisons between the
> vertical and
> any simple wire resonant dipole. That means six S-units. That means a
> one watt
> signal into the dipole will be better than 1000 watts into the vertical!
>
> The installation of a semi-effective ground system for the vertical would
> require
> multiple tuned counterpoise wires that are far more troublesome to employ
> than
> just using a simple resonant dipole.

______________________________________________________________
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

AC7AC

Re: Antennas for K1 Field Use

CONTENTS DELETED

The author has deleted this message.

w7aqk

Re: Antennas for K1 Field Use

In reply to this post by Mike Morrow-3

Mike and All,

Au contraire, mon ami! Don't be too quick to dismiss using a vertical.
It's not quite as simple as throwing something over a tree, but you have to
have a tree!

Here in the desert, verticals are often the best choice. Some ham friends
of mine and I go out frequently on camping trips, and unless we go to high
ground, trees are pretty much non-existent. A couple of these guys have
fabricated vertical installations that are very good performers. A 20 meter
vertical we used was elevated about 6 feet, and 30 radials were staked out
around it. The whole job only took about an hour to erect. A 40 meter
vertical is in the works. Performance on the 20 meter vertical was
excellent, so we then did two of them and phased them. Of course, results
were even better.

I have a collar device which slides into my trailer hitch. I can put a mast
section in the collar, and then an R7 vertical on top of it. That gives me
40 through 10 with good results. I'm not saying a nice, high dipole
wouldn't be as good or better, but I've used R7's for years, both at home
and away, and I don't feel very deprived. Well, I'd love to have a nice
beam installation, but that's just not possible, at home anyway.

Speaking of beams, I also have one of Vern Wright's portable beams. I've
used it several times now, and it works great! I put mine up about 25 feet
with a collapsible flagpole, and it is a relatively easy process. I
intended to use it this year for Field Day, but we were on high ground, and
the trees were too close. On other outings though, it has been a very good
performer.

I've commented multiple times on how to make some of the various portable
vertical systems, like the PAC-12, Buddistick, and MP-1, work considerably
better than the "out-of-the-box" setup. So, I won't repeat all of that.
It's not very hard though, and the results are quite rewarding.

If circumstances allow you to put up a dipole, that's probably what you
should do. But don't think a vertical system is not an effective option.
You certainly don't have to suffer the 30 db or so deficiency that Mike
suggests, or anything close to it. With just a little extra effort you can
be within an S unit or so of a dipole, and you might even sound better to a
DX station.

Dave W7AQK
.

original Message -----
From: "Mike Morrow" <[hidden email]>
To: <[hidden email]>
Cc: <[hidden email]>
Sent: Sunday, July 12, 2009 7:19 PM
Subject: Re: [Elecraft] Antennas for K1 Field Use

David Cutter

Re: Antennas for K1 Field Use

Dave

I agree about verticals elevated off the ground with raised radials.

Could you describe your phasing method, was it passive, ie a reflector?

Did you use fishing poles to hold up your wires?

David
G3UNA

>
> Here in the desert, verticals are often the best choice. Some ham friends
> of mine and I go out frequently on camping trips, and unless we go to high
> ground, trees are pretty much non-existent. A couple of these guys have
> fabricated vertical installations that are very good performers. A 20 meter
> vertical we used was elevated about 6 feet, and 30 radials were staked out
> around it. The whole job only took about an hour to erect. A 40 meter
> vertical is in the works. Performance on the 20 meter vertical was
> excellent, so we then did two of them and phased them. Of course, results
> were even better.
>
> >
> If circumstances allow you to put up a dipole, that's probably what you
> should do. But don't think a vertical system is not an effective option.
> You certainly don't have to suffer the 30 db or so deficiency that Mike
> suggests, or anything close to it. With just a little extra effort you can
> be within an S unit or so of a dipole, and you might even sound better to a
> DX station.
>
> Dave W7AQK
> .

Vic K2VCO

Re: Antennas for K1 Field Use

In reply to this post by w7aqk

David Y. wrote:
> Mike and All,
>
> Au contraire, mon ami! Don't be too quick to dismiss using a vertical.
> It's not quite as simple as throwing something over a tree, but you have to
> have a tree!

Some years ago I made a 20M vertical out of a collapsible 16' (4.9M) fishing pole. I
wrapped some wire around it to make a full-size 1/4w vertical element, and made a base
section out of a couple of pieces of PVC pipe, making a support 6' (1.8M) high. I attached
four 6' collapsible whip antennas to the bottom of the pole (when set up, this was the 6'
level) for a shortened ground plane. The center conductor of the coax went to the vertical
whip and the braid to a small loading coil and thence to the ground plane. I also made a
choke balun for the coax.

The whole thing fit in a small package about 4' (1.2M) long and could be set up almost
anywhere in minutes. The pvc support had a sharp stake attached to the bottom, and the
antenna was guyed by three poly ropes. With a bit more wire you could make a 40M version
which would only be slightly less efficient than a full-size vertical.

The method of using shortened radials with a loading coil or stub is discussed by Moxon in
his book "HF Antennas for all locations" and modeling shows that the reduction in
efficiency can be quite small.

How did it work? Not badly, although usually not as well as a dipole at 25' (7.6M). It was
very easy to put up and required no trees or other supports. It was especially good to
take to the beach where it could be operated close to salt water.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
______________________________________________________________
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

John W2XS

Re: Antennas for K1 field use

In reply to this post by g3yiq

Jackite has a ground mount for the Jackite 28-foot and 31-foot poles:

http://www.jackite.com/

I have had good luck with the Earthworm ground mount for the SD20 poles:

http://www.shadeusa.com/beach_umbrella_holders.htm

These can provide the support for the center of my favorite portable antenna: an inverted V, even in a treeless environment.

73,

John W2XS

Craig Smith

Re: Antennas for K1 field use

<> Jackite has a ground mount for the Jackite 28-foot and 31-foot poles:

These are excellent and well worth the $. Very nicely made and sturdy
enough to drive into the ground. Make sure you get the foam rings matched
to your mast. This ring surrounds the mast and makes a snug fit into the
mount and prevents a stress concentration between the mount and mast - very
nice. I have 3 of these and use them constantly.

Their so-called "Ladder-mount" is also useful. I found by accident that it
will conveniently fit one of the green/yellow 5 foot steel fence posts that
you can find at any hardware or garden store. Not sure what the proper name
for them is. They are made from steel sheet, kind of U shape cross section
and metal tabs on one side for attaching fence wire. Put bolts through the
holes in the ladder mount then slip over the top of the fence post so that
the lower mounting tab of the mount rests against one of the tabs on the
fence post. Hard to describe in words, but if you get the pieces in front
of you it will become obvious. The benefit of all this is that your 31 ft
Jackite pole now essentially becomes 35 feet! What ham could resist that???

73 Craig AC0DS

______________________________________________________________
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

w7aqk

Re: Antennas for K1 Field Use

In reply to this post by David Cutter

David and all,

The phasing system we used is described in most recent issues of the ARRL
Antenna Handbook. In the 20th edition of that book, it is on page 8-31,
under the sub-heading "Directional Switching of Arrays".

Some pruning and trimming is necessary, but basically, two 1/4 wavelength
verticals are spaced 1/2 wave apart. We elevated our verticals about 5 or 6
feet. The phasing lines were made using RG-6 (75 ohm coax), and one
vertical is fed with an approx. 3/4 wavelength section, and the other with
an approx. 1/4 wavelength section. The two sections of coax are joined
together with a T-connector. 50 ohm coax is used to feed the system to the
rig.

The configuration described above gives you "end-firing". If you want to
switch to fire broadside, an approx. 1/2 wave length of RG-6 is added to the
already attached 1/4 wavelength section. The use of RG-6 for the phasing
line more or less matches the antenna array to 50 ohms at the "T". The
verticals themselves are something like 35 ohms at the base, so the 75 ohm
coax doubles as sort of a tuning stub. At least I think that's what it
does.

We used aluminum elements for the verticals, but wire could be used I would
think. It's usually better to use larger diameter material if possible.
I've seen all sorts of material used for verticals like this. One method
that worked pretty well was to use coax for the vertical element (like
RG-8), and just use the shield as the actual element. You can suspend the
coax from tree limbs, or whatever.

Our radials were sloping downward, but still raised slightly off the ground.
It probably would have been better if they were elevated even more, but info
I have read in "white papers" like the ones written by K6KL tells me that
even a little bit off the ground is good.

We manually switched the phasing from end fire to broadside, but you could
set up a relay system to do that.

Hope this gives you some idea of how we did it.

Dave W7AQK

----- Original Message -----
From: <[hidden email]>
To: <[hidden email]>; "Mike Morrow" <[hidden email]>; "David Y."
<[hidden email]>
Cc: <[hidden email]>
Sent: Monday, July 13, 2009 2:38 AM
Subject: Re: [Elecraft] Antennas for K1 Field Use

> Dave
>
> I agree about verticals elevated off the ground with raised radials.
>
> Could you describe your phasing method, was it passive, ie a reflector?
>
> Did you use fishing poles to hold up your wires?
>
> David
> G3UNA
>
>
>>
>> Here in the desert, verticals are often the best choice. Some ham
>> friends
>> of mine and I go out frequently on camping trips, and unless we go to
>> high
>> ground, trees are pretty much non-existent. A couple of these guys have
>> fabricated vertical installations that are very good performers. A 20
>> meter
>> vertical we used was elevated about 6 feet, and 30 radials were staked
>> out
>> around it. The whole job only took about an hour to erect. A 40 meter
>> vertical is in the works. Performance on the 20 meter vertical was
>> excellent, so we then did two of them and phased them. Of course,
>> results
>> were even better.
>>
>> >
>> If circumstances allow you to put up a dipole, that's probably what you
>> should do. But don't think a vertical system is not an effective option.
>> You certainly don't have to suffer the 30 db or so deficiency that Mike
>> suggests, or anything close to it. With just a little extra effort you
>> can
>> be within an S unit or so of a dipole, and you might even sound better to
>> a
>> DX station.
>>
>> Dave W7AQK
>> .