Re: [Elecraft] Small QRP antenna

[Jim Allen]

Sorry, Jim, you are misquoting the wrong guy.  Tweren't me, McGee.

73 Jim Allen W6OGC 
> Message: 24
> Date: Fri, 30 Dec 2016 13:25:28 -0800
> From: Jim Brown <j...@audiosystemsgroup.com>
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] Small QRP antenna
> Message-ID:
><b7aeba7c-1bed-abbf-4557-e9bf65748...@audiosystemsgroup.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> Sorry Jim, you're mistaken on many counts.
> 
> An antenna does not have VF, but the wire we use for it does. VF of an 
> infinitely thin bare wire in free space is 1.  Surrounding it with a 
> dielectric (insulation) makes it longer electrically, usually by a few 
> percent. So does making the wire fatter. These differences are usually 
> described using VF.
> 
> Placing a conductor close to earth (within a few inches) causes it to 
> couple to the earth, which also makes it electrically longer. We could 
> also describe this using VF.
> 
> VF is NOT constant with frequency, whether in a transmission line or in 
> wire. VF of all transmission lines starts out quite small at audio 
> frequencies, rises quickly through the audio spectrum, eventually 
> reaching a near constant value at mid-VHF. It is this near-constant 
> value that is computed by the simple equation that doesn't include 
> frequency. For most lines, VF has reached about 98% of its final value 
> at 2 MHz.
> 
> Likewise, Zo is not constant with frequency, nor is it a pure 
> resistance. It starts out quite high at low audio frequencies and is 
> dominated by capacitance. Zo falls rapidly in the audio spectrum, and is 
> quite close to its final value at 2 MHz, but is still capacitive, 
> typically 1-2 ohms.
> 
> This can be clearly seen in N6BV's TLW software that comes on the CD 
> with the ARRL Antenna Book. Choose your favorite coax, set the frequency 
> to 2 MHz, make the line 300-400 ft long, and terminate it in a pure 
> resistance. TLW will tell you Zo. Now select Volt/Current next to the 
> Graph button (lower right corner) and you'll see  that there are 
> standing waves on the line (the graphs are not a straight line). Now set 
> the Load to the R and X values for Zo and hit Graph again. Now the V and 
> I lines are nearly straight, indicating quite low SWR. They would lay 
> exactly on top of each other, but the R and X values for Zo are rounded 
> off.
> 
> The fact that Zo, VF, and attenuation vary with frequency is clearly 
> predicted by the full transmission line equations. There's a brief 
> discussion of this in
> http://k9yc.com/Coax-Stubs.pdf
> which also shows how VF and attenuation can be computed and plotted vs 
> frequency by making two measurements of a sample with a vector analyzer 
> like the AIM, SARK, and VNWA analyzers.  The two measurements are then 
> exported to AC6LA's excellent freeware Excel spreadsheet called ZPlots.
> 
> There's a longer discussion of this, specifically written for audio 
> people, but obviously important for radio, in
> http://k9yc.com/TransLines-LowFreq.pdf
> 
> 73, Jim K9YC
> 
>> On Fri,12/30/2016 11:12 AM, Jim Allen wrote:
>> but ?velocity factor? is a characteristic of transmission lines. 
>> Interestingly, it is independent of frequency (up to the limit of the 
>> dielectric). It depends on the geometry of the line and the dielectric 
>> material. > > Antennas don?t have a velocity factor. The shortened elements 
>> are caused by capacitive loading against (RF) ground. There is a percentage 
>> of the free-space electrical length due to capacitive loading, but it is not 
>> a velocity factor.
> 
> *
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Jim Brown]

Sorry Jim, you're mistaken on many counts.

An antenna does not have VF, but the wire we use for it does. VF of an 
infinitely thin bare wire in free space is 1.  Surrounding it with a 
dielectric (insulation) makes it longer electrically, usually by a few 
percent. So does making the wire fatter. These differences are usually 
described using VF.


Placing a conductor close to earth (within a few inches) causes it to 
couple to the earth, which also makes it electrically longer. We could 
also describe this using VF.


VF is NOT constant with frequency, whether in a transmission line or in 
wire. VF of all transmission lines starts out quite small at audio 
frequencies, rises quickly through the audio spectrum, eventually 
reaching a near constant value at mid-VHF. It is this near-constant 
value that is computed by the simple equation that doesn't include 
frequency. For most lines, VF has reached about 98% of its final value 
at 2 MHz.


Likewise, Zo is not constant with frequency, nor is it a pure 
resistance. It starts out quite high at low audio frequencies and is 
dominated by capacitance. Zo falls rapidly in the audio spectrum, and is 
quite close to its final value at 2 MHz, but is still capacitive, 
typically 1-2 ohms.


This can be clearly seen in N6BV's TLW software that comes on the CD 
with the ARRL Antenna Book. Choose your favorite coax, set the frequency 
to 2 MHz, make the line 300-400 ft long, and terminate it in a pure 
resistance. TLW will tell you Zo. Now select Volt/Current next to the 
Graph button (lower right corner) and you'll see  that there are 
standing waves on the line (the graphs are not a straight line). Now set 
the Load to the R and X values for Zo and hit Graph again. Now the V and 
I lines are nearly straight, indicating quite low SWR. They would lay 
exactly on top of each other, but the R and X values for Zo are rounded 
off.


The fact that Zo, VF, and attenuation vary with frequency is clearly 
predicted by the full transmission line equations. There's a brief 
discussion of this in

http://k9yc.com/Coax-Stubs.pdf
which also shows how VF and attenuation can be computed and plotted vs 
frequency by making two measurements of a sample with a vector analyzer 
like the AIM, SARK, and VNWA analyzers.  The two measurements are then 
exported to AC6LA's excellent freeware Excel spreadsheet called ZPlots.


There's a longer discussion of this, specifically written for audio 
people, but obviously important for radio, in

http://k9yc.com/TransLines-LowFreq.pdf

73, Jim K9YC

On Fri,12/30/2016 11:12 AM, Jim Allen wrote:

but “velocity factor” is a characteristic of transmission lines. Interestingly, it is 
independent of frequency (up to the limit of the dielectric). It depends on the 
geometry of the line and the dielectric material. > > Antennas don’t have a 
velocity factor. The shortened elements are caused by capacitive loading against (RF) 
ground. There is a percentage of the free-space electrical length due to capacitive 
loading, but it is not a velocity factor.



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Jim Allen]

My experience matches this precisely.

~35 years ago, I built the huge quad described in "Evolution of a Quad Array" 
from an article in QST, May 1978, IIRC.  It was done with help from experienced 
antenna builders, measured very meticulously.  When we finally got it up on the 
tower, it was awful, weird SWRs, no F/B, nothing seemed right.  I checked all 
the feedlines and connectors.  Nothing amiss.

I had found a roll of No. 12 insulated wire at a surplus place and used that 
for all the elements.  In discussions with the owner of the quad in the article 
and the designer, we concluded the problem was the insulation, as the design 
used enameled No. 12, different velocity factor.  I spent the next ~2 weeks of 
evenings, until 10-11 at night, with a pocket knife on my roof scraping 
insulation from ~1200' of wire in situ.  Not only was it no fun, the neighbors 
never looked at me the same again.  Once that was done, the antenna performed 
wonderfully, as expected.
73 Jim Allen W6OGC 
> Walt, I differ, antenna wires do have a velocity factor to consider. I built 
> a 6 meter Moxon beam for my grandson out of insulated wire, and the resonant 
> frequency was considerably low. Stripping the insulation from the wire 
> brought its resonance point up to what was expected. The only reason was 
> because the velocity factor for the insulated wire was less than that of 
> non-insulated wire. 73, Don W3FPR

> On 12/29/2016 6:33 PM, Walter Underwood wrote: > This is quite likely overly 
> pedantic, but “velocity factor” is a characteristic of transmission lines. 
> Interestingly, it is independent of frequency (up to the limit of the 
> dielectric). It depends on the geometry of the line and the dielectric 
> material. > > Antennas don’t have a velocity factor. The shortened elements 
> are caused by capacitive loading against (RF) ground. There is a percentage 
> of the free-space electrical length due to capacitive loading, but it is not 
> a velocity factor. I don’t think this has a snappy shorthand other than 
> “electrical lengthening due to capacitive loading”. > > For example, dipoles 
> with capacity caps on the ends, like the N6BT designs, don’t change the 
> velocity of propagation along the elements. They use massive capacity loading 
> on the ends (the high-voltage part of the dipole) to shorten the elements. > 
> > 
> http://www.force12inc.com/products/sigma-20-hd-20-meter-heavy-duty-vertical-dipole.html
>  
> 
>  > > OK, overly pedantic mode off, plus I’ve nearly hit the limit of what I 
> remember from my fields and waves class decades ago. I was pretty happy to 
> get a B- in that class. > > wunder > K6WRU > Walter Underwood > CM87wj > 
> http://observer.wunderwood.org/ (my blog) >
> 
> Sent from my iPad
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Jim Brown]

On Thu,12/29/2016 3:07 PM, Bill Johnson wrote:

Having "only" 5 watts doesn't change the need for proper termination and
antenna match.


By proper termination, I think you're thinking about SWR and a match to 
the transmitter. This thread is several days and 20+ posts old, but I 
think I remember that the intent of the original poster was for portable 
operation. But I could be wrong. :)


There are two reasons for low SWR and "matching." One is to get the 
transmitter to provide power to the transmission line. If the mismatch 
is too high, the transmitter will "fold back" (reduce its drive to 
reduce its output power) to protect itself. Providing that match is the 
function of an "antenna tuner."


The second reason is to reduce loss in the line due to a mismatch. The 
SWR in a transmission line is determined entirely by the match between 
the antenna and the line. It is NOTHING to do with the match between the 
transmitter and the line.  In typical QRP portable setups, transmission 
lines are rarely long enough for loss to matter, so the match between 
the antenna and the line usually doesn't matter. And the antenna tuner 
takes care of match at the transmitter so that the output stage can 
supply its full power.


73, Jim K9YC


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[David Gilbert]

You aren't being overly pedantic ... you're simply being wrong. Velocity 
factor for electromagnetic emmissions is the ratio of any signal in any 
environment compared to its value in free space.  The velocity factor of 
a signal in a transmission line is a function of geometry and 
surrounding materials, and the same is true of a signal in a single wire.


https://en.wikipedia.org/wiki/Velocity_factor  if you aren't convinced.

Dave   AB7E



On 12/29/2016 4:33 PM, Walter Underwood wrote:

This is quite likely overly pedantic, but “velocity factor” is a characteristic 
of transmission lines. Interestingly, it is independent of frequency (up to the 
limit of the dielectric). It depends on the geometry of the line and the 
dielectric material.

Antennas don’t have a velocity factor. The shortened elements are caused by 
capacitive loading against (RF) ground. There is a percentage of the free-space 
electrical length due to capacitive loading, but it is not a velocity factor. I 
don’t think this has a snappy shorthand other than “electrical lengthening due 
to capacitive loading”.

For example, dipoles with capacity caps on the ends, like the N6BT designs, 
don’t change the velocity of propagation along the elements. They use massive 
capacity loading on the ends (the high-voltage part of the dipole) to shorten 
the elements.

http://www.force12inc.com/products/sigma-20-hd-20-meter-heavy-duty-vertical-dipole.html
 


OK, overly pedantic mode off, plus I’ve nearly hit the limit of what I remember 
from my fields and waves class decades ago. I was pretty happy to get a B- in 
that class.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)


On Dec 29, 2016, at 2:08 PM, Jim Brown  wrote:

On Thu,12/29/2016 1:53 PM, Bill Frantz wrote:

If this is really what is going on, then a bit longer than 1/8 wave should be 
about right for radials on/under the ground.

I did an NEC study several years ago placing a half wave dipole at heights 
above ground from several feet down to an inch, and varied the length of the 
dipole so that it remained resonant at each height. From that I plotted VF. As 
close to the earth as I could model it, VF was about 0.7. At heights of 3 ft or 
more, VF on 160M was close to 1.

N6LF published a detailed study of radial lengths and recommended an optimum 
length for elevated radials slightly less than a quarter wave. His basis was 
that making them slightly shorter caused current distribution between them to 
be more equal, which reduces ground losses. Rudy's website is a wealth of great 
info about radials.

73, Jim K9YC

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to wun...@wunderwood.org

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to xda...@cis-broadband.com


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Wes Stewart]

Not so.

On 12/29/2016 4:33 PM, Walter Underwood wrote:

This is quite likely overly pedantic, but “velocity factor” is a characteristic 
of transmission lines. Interestingly, it is independent of frequency (up to the 
limit of the dielectric).


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Don Wilhelm]

Walt,

I differ, antenna wires do have a velocity factor to consider.  I built 
a 6 meter Moxon beam for my grandson out of insulated wire, and the 
resonant frequency was considerably low.  Stripping the insulation from 
the wire brought its resonance point up to what was expected.
The only reason was because the velocity factor for the insulated wire 
was less than that of non-insulated wire.


73,
Don W3FPR

On 12/29/2016 6:33 PM, Walter Underwood wrote:

This is quite likely overly pedantic, but “velocity factor” is a characteristic 
of transmission lines. Interestingly, it is independent of frequency (up to the 
limit of the dielectric). It depends on the geometry of the line and the 
dielectric material.

Antennas don’t have a velocity factor. The shortened elements are caused by 
capacitive loading against (RF) ground. There is a percentage of the free-space 
electrical length due to capacitive loading, but it is not a velocity factor. I 
don’t think this has a snappy shorthand other than “electrical lengthening due 
to capacitive loading”.

For example, dipoles with capacity caps on the ends, like the N6BT designs, 
don’t change the velocity of propagation along the elements. They use massive 
capacity loading on the ends (the high-voltage part of the dipole) to shorten 
the elements.

http://www.force12inc.com/products/sigma-20-hd-20-meter-heavy-duty-vertical-dipole.html
 


OK, overly pedantic mode off, plus I’ve nearly hit the limit of what I remember 
from my fields and waves class decades ago. I was pretty happy to get a B- in 
that class.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Walter Underwood]

This is quite likely overly pedantic, but “velocity factor” is a characteristic 
of transmission lines. Interestingly, it is independent of frequency (up to the 
limit of the dielectric). It depends on the geometry of the line and the 
dielectric material.

Antennas don’t have a velocity factor. The shortened elements are caused by 
capacitive loading against (RF) ground. There is a percentage of the free-space 
electrical length due to capacitive loading, but it is not a velocity factor. I 
don’t think this has a snappy shorthand other than “electrical lengthening due 
to capacitive loading”.

For example, dipoles with capacity caps on the ends, like the N6BT designs, 
don’t change the velocity of propagation along the elements. They use massive 
capacity loading on the ends (the high-voltage part of the dipole) to shorten 
the elements.

http://www.force12inc.com/products/sigma-20-hd-20-meter-heavy-duty-vertical-dipole.html
 


OK, overly pedantic mode off, plus I’ve nearly hit the limit of what I remember 
from my fields and waves class decades ago. I was pretty happy to get a B- in 
that class.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Dec 29, 2016, at 2:08 PM, Jim Brown  wrote:
> 
> On Thu,12/29/2016 1:53 PM, Bill Frantz wrote:
>> If this is really what is going on, then a bit longer than 1/8 wave should 
>> be about right for radials on/under the ground.
> 
> I did an NEC study several years ago placing a half wave dipole at heights 
> above ground from several feet down to an inch, and varied the length of the 
> dipole so that it remained resonant at each height. From that I plotted VF. 
> As close to the earth as I could model it, VF was about 0.7. At heights of 3 
> ft or more, VF on 160M was close to 1.
> 
> N6LF published a detailed study of radial lengths and recommended an optimum 
> length for elevated radials slightly less than a quarter wave. His basis was 
> that making them slightly shorter caused current distribution between them to 
> be more equal, which reduces ground losses. Rudy's website is a wealth of 
> great info about radials.
> 
> 73, Jim K9YC
> 
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to wun...@wunderwood.org

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Edward R Cole]

I've stayed out of this discussion so far.

I can comment on building a J-pole for 10m and 6m.  I used a 24-foot 
tall 1-inch diameter aluminum mast held by a 8-foot section of 
Rohn-25G "planted" in the ground (no concrete).  I used 1/4 wave stub 
space 2-inch running parallel to the mast from ground level on 10m. 
the bottom ends were strapped together and coax was run up  about 
6-inches above the ground end with center tied to stub and shield to 
mast.   Good 50-ohm match over about 28.300-28.700 MHz and under 2:1 
over a MHz bandwidth.  I did not ground the J-pole other than that 
provided by the short tower.


I added a 6m J-pole to the top section running a separate coax feed 
and it had little effect on tuning the 10m antenna.  I tuned it for 
52-MHz FM but found the only repeater was at marginal distance with 
no local activity so its not in current use (the 24-foot pole acts as 
end support for my 80/40m inverted-V with long nylon cord so the two 
antenna do not interact).


I did make a coax coil RF choke at base of the antenna to inhibit 
common-mode radiation and coax was buried a couple inches deep for 
about 50-feet run to the house.  I always intended to add buried 
radials but never got around to it.


I had this up as a web-page until my site was hacked a few years ago 
and never restored it.


I also have a very-short inverted-L on 600m: 43-foot by 122-foot 
which is currently down for repair.  My radials were lain on ground 
and at 70-foot not anywhere near 1/4 wave (465-foot).  Ground 
resistance is 20-ohms measured whereas radiation resistance is 0.83 
ohm per EZNEC5.  Obviously not efficient, but definitely QRP when 
running 100w (less than a watt radiated).  Worms are cozy!  SWR 
bandwidth is 5-KHz.


Of course neither are QRP portable antennas.  One could make the 10m 
version from ladder line plus 1/2 wave top wire either as a zepp or J-pole.
I think the zepp configuration would be nice for quick portable use 
if you have two vertical supports (one could be an 8-foot aluminum 
pole with standoff rod for the 1/4 wave section).  I might give that 
a look for use with my trailer in a campground while RVing.


73, Ed - KL7UW
  http://www.kl7uw.com
Dubus-NA Business mail:
  dubus...@gmail.com 


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Bill Johnson]

Having "only" 5 watts doesn't change the need for proper termination and
antenna match.  5 Watts, or any wattage, for that matter can be a problem.
5 watts MAY make the problem less physically an problem.  

73,
Bill
K9YEQ

-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Jim
Brown
Sent: Thursday, December 29, 2016 12:59 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna

Nothing in this post is true. Optimum length for a counterpoise is a quarter
wave. Radials are a form of counterpoise, and their optimum length is also a
quarter wave. More radials reduce ground losses. 
Failing to provide an adequate counterpoise will cause the antenna's return
current to flow on your coax, which makes the rig hot with RF. 
That's not much of a problem with 5W, but it can be a very big deal with
100W or more.

Of course, it does depend on what you mean by "much" and "minimal." 
Inadequate counterpoise or radial systems can easily reduce you signal by 6
dB. That's an S-unit, and it reduces your 5W signal to 1.25W.  I wouldn't
call that minimal or "not much."

73, Jim K9YC

On Thu,12/29/2016 7:30 AM, Fred Moore wrote:
> With an end fed 1/4 wave you only need a counterpoise that is about 
> .05 wave length.  it can be the coax or another counterpoise.  
> Although a counterpoise has some effect on radiation pattern of a quarter
wave
> radiator, it is minimal.   You won't see much improvement in performance
> by going above .05 wave length..  it's not worth the trouble to 
> increase the counterpoise length..


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html Message
delivered to k9...@live.com
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Bill Johnson]

Mike,  
Over the years I have come to know Don as always succinct and to the point.
AND, he does know his stuff nearly 100% or he will not comment.  He will not
waste his time responding to this accolade.  We go back to the K2 field test
and he was much a pleasure to work with then as now.  Oh, I and I think his
knowledge and writing skill has improved with age!

73,
Bill
K9YEQ

-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Mike
Morrow
Sent: Thursday, December 29, 2016 12:09 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna

Don wrote:

> A 1/2 wave radiator fed at the end theoretically does not need any 
> counterpoise, but in practice it does - but only needs to be about 
> 0.05 wavelength long.
>
> Refer to some antenna books (the ARRL has a good one) or the ARRL 
> Handbook for good information about basic antennas.

The concise clarity of Don's input to this thread is refreshing.  Such seem
to occur rarely in ham discussions about antennas.

With respect to classical end-fed half-wave antennas, I think of the end-fed
Zepp[elin] and the common VHF J-poles.

Mike / KK5F
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html Message
delivered to k9...@live.com
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Wes Stewart]

Except for what I'm about to say, what Jim says in his first sentence is true, 
which of course includes his post:-)


The velocity of propagation in a wire, near to, on, or below the ground is 
different from the same wire in free space.  How different?  Most people don't 
know, don't care or couldn't determine it if they wanted to.  But it has been 
shown that for these radials, especially when few in number, efficiency actually 
/improves /when their lengths are less than 1/4 lambda. See: "Experimental 
Determination of Ground System Performance for HF Verticals...", by Rudy 
Severns,* N6LF, QEX, Jan/Feb 2009 pp 48-52.


* I can't recommend highly enough Rudy's work on vertical antennas. 
http://rudys.typepad.com/  He writes this stuff faster than I can read it.


Wes  N7WS

On 12/29/2016 11:58 AM, Jim Brown wrote:
Nothing in this post is true. Optimum length for a counterpoise is a quarter 
wave. Radials are a form of counterpoise, and their optimum length is also a 
quarter wave. More radials reduce ground losses. Failing to provide an 
adequate counterpoise will cause the antenna's return current to flow on your 
coax, which makes the rig hot with RF. That's not much of a problem with 5W, 
but it can be a very big deal with 100W or more.


Of course, it does depend on what you mean by "much" and "minimal." Inadequate 
counterpoise or radial systems can easily reduce you signal by 6 dB. That's an 
S-unit, and it reduces your 5W signal to 1.25W.  I wouldn't call that minimal 
or "not much."


73, Jim K9YC

On Thu,12/29/2016 7:30 AM, Fred Moore wrote:

With an end fed 1/4 wave you only need a counterpoise that is about .05
wave length.  it can be the coax or another counterpoise. Although a
counterpoise has some effect on radiation pattern of a quarter wave
radiator, it is minimal.   You won't see much improvement in performance
by going above .05 wave length..  it's not worth the trouble to increase
the counterpoise length..


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Don Wilhelm]

Fred,

You summed up antennas in general very well, and especially end fed dipoles.

I would like to add a bit to your item 7 - dealing with the matching of 
a half wave end fed to a 50 ohm line - and the counterpoise wire.


There are two common ways of matching to an end fed half wave.  One is 
by using a tuned resonant circuit with a link (or tap) to the coax.  In 
the case of a link, the short counterpoise needs to be connected to the 
'bottom' end of the resonant circuit.  If the link is isolated from the 
winding of the resonant circuit, the coax shield cannot provide that 
function, the counterpoise must be a separate wire.
If the matching network is the commonly used 9:1 unun, then the bottom 
of the high impedance side is connected to the coax shield, and the coax 
shield can serve as the counterpoise wire.  That is why one needs to use 
a short length of coax with those antennas and not connect directly to 
the rig.


Most commercial end fed matching networks can use the coax shield and no 
counterpoise wire is necessary, but you must use a short length of coax.


73,
Don W3FPR

On 12/29/2016 4:49 PM, Fred Jensen wrote:


7.  Feeding a half-wave at the end would seem to require that there be
"something" for the other side of the circuit so current can flow.
Practically, because the impedance is very high, the current is very low
and the "something" doesn't have to be very much.  In fact, if the
primary of the matching transformer is fed with a couple feet of coax,
the shield will provide that "something."  So will the wiring around you
[headphone cable, power cable, key cable], and you if you're holding
your radio.


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Jim Brown]

On Thu,12/29/2016 1:53 PM, Bill Frantz wrote:
If this is really what is going on, then a bit longer than 1/8 wave 
should be about right for radials on/under the ground.


I did an NEC study several years ago placing a half wave dipole at 
heights above ground from several feet down to an inch, and varied the 
length of the dipole so that it remained resonant at each height. From 
that I plotted VF. As close to the earth as I could model it, VF was 
about 0.7. At heights of 3 ft or more, VF on 160M was close to 1.


N6LF published a detailed study of radial lengths and recommended an 
optimum length for elevated radials slightly less than a quarter wave. 
His basis was that making them slightly shorter caused current 
distribution between them to be more equal, which reduces ground losses. 
Rudy's website is a wealth of great info about radials.


73, Jim K9YC

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Fred Jensen]

Ground rods are pretty ineffective at RF, Dick although I'm not 
surprised your Inv-L works good.  It all depends on the quality of the 
"earth" around your antenna.  If yours is good, you're fortunate.  
Saltwater is great.  Keep in mind that you're trying to provide a return 
for an electromagnetic field which is extended in space.  The lower you 
can make the resistance of that return, the better.


If your radial field is elevated off the ground, they need to be 1/4 
wave [or so] long.  One will make a big difference over none.  Two in 
opposite directions will be better but not by as much. Additional ones 
will help but to a decreasing degree.


If your radial field is on the ground or buried, length doesn't really 
matter, nor do they all have to be the same length, straight, or evenly 
spaced.  All you're really doing with buried conductors is enhancing the 
conductivity of the "earth" return path over the space of the field.


Fred K6DGW
Sparks NV DM09dn
Washoe County

--Northern California Contest Club
--CU in the Cal QSO Party
--7-8 Oct 2017


On 12/29/2016 8:49 AM, Richard Fjeld wrote:

With reference to below, I have a question please.  I put up a quarter
wave inverted-L for 160 meters.  My only counterpoise is the ground rods
at the base of the tower.  I wasn't expecting much, but it does so well
I'd like to add a decent counterpoise.

If I bury a quarter wave wire, would it be best to put it under the
Ariel wire, or opposite from it?
Thanks in advance,
Dick, n0ce



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Bill Frantz]

I may be seriously wrong, but shorter than 1/4 wave ground 
mounted radials are probably affected by the same ground tuning 
effects that allow a Beverage on the Ground antenna to be 
considerably shorter than one mounted above the ground. If this 
is really what is going on, then a bit longer than 1/8 wave 
should be about right for radials on/under the ground.


73 Bill AE6JV

On 12/29/16 at 9:05 AM, donw...@embarqmail.com (Don Wilhelm) wrote:

With buried radials, they do not have to be 1/4 wave long, and 
a single one will probably not make much difference over your 
ground rod.
What you want to accomplish is a "ground screen", which means 
many short (about 1/8 wavelength) close to the base of the 
radiator and a few extending out further (to 1/4 or 1/2 wavelength).


Ground conductivity plays a great part in buried radials, and 
what you are trying to accomplish is to increase the ground 
conductivity in the area at the base of the antenna.


If you were instead using elevated radials, they would have to 
be resonant - think of the various "ground plane" antennas that 
have been published - 1/4 wave radiator plus 2 or 4 1/4 wave radials.
Buried radials do not have to be resonant, elevated radials 
must be resonant.  The ground effects will alter the resonance 
of buried radials while radials in the air are a part of the 
total antenna resonance.

---
Bill Frantz|Security, like correctness, is| Periwinkle
(408)356-8506  |not an add-on feature. - Attr-| 16345 
Englewood Ave
www.pwpconsult.com |ibuted to Andrew Tanenbaum| Los Gatos, 
CA 95032


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Fred Jensen]

I'm fairly certain that Fred meant 1/2 wave ... correct hand, wrong 
finger, happens to me all the time.


This has been going on for a long time, here's a summary and maybe it 
can rest for awhile:


1.  Elecraft ATU's are L-networks.  Theoretically, one of the 4 L-net 
configurations will match any impedance to any other impedance.  
Practically, for some attempted matches, the required values of L and/or 
C become unattainable.


2.  Any conductor you can get power into will radiate.

3.  "Random" length wires will exhibit random impedances at the end [or 
anywhere else along them].  ATU's will *generally* match those 
impedances to 50 ohms [or close] for you.


4.  Some "random" lengths are better than others for matching with an 
L-network.  They all radiate however [see #2].  41-43 ft is one, ~26 ft 
is another.  Random length conductors require a counterpoise of some sort.


5.  All half-wavelength conductors are created equal in terms of 
current/voltage distribution.  The ends are open circuits ... zero 
current/infinite voltage.  The center is a short circuit ... infinite 
current/zero voltage.  The power on the conductor is constant [ignoring 
wire resistance].  It doesn't matter where you feed it.  A full-wave 
wire is just two half-waves fed in series.


6.  Infinities aren't real of course, the ends are high voltage/small 
current = Hi-Z [several K ohms].  The center is high current/small 
voltage = Lo-Z [40-70 ohms].


7.  Feeding a half-wave at the end would seem to require that there be 
"something" for the other side of the circuit so current can flow.  
Practically, because the impedance is very high, the current is very low 
and the "something" doesn't have to be very much.  In fact, if the 
primary of the matching transformer is fed with a couple feet of coax, 
the shield will provide that "something."  So will the wiring around you 
[headphone cable, power cable, key cable], and you if you're holding 
your radio.


8.  For NEC-2 models, connecting a source to the end of the half-wave 
wire means there is no return path and it essentially tries to divide by 
zero, maxing out a floating-point value.  It's a little more complex 
than that, but that's the essence.  In such a model, you need to provide 
a return path for a very small current. On 20 meters, one of my field 
half-waves requires about 6 in. Anything longer makes no difference.


One easy way to construct a "random" length antenna is to peel the outer 
cover from a length of RG-58, separate the braid at the bottom and pull 
the center conductor through the hole.  The empty braid then becomes the 
counterpoise and you can trim it to find the "sweet spot" your ATU can 
easily match.


Hope this helps on the subject.  Happy New Year to all

Fred K6DGW
Sparks NV DM09dn
Washoe County

--Northern California Contest Club
--CU in the Cal QSO Party
--7-8 Oct 2017


On 12/29/2016 7:30 AM, Fred Moore wrote:

With an end fed 1/4 wave you only need a counterpoise that is about .05
wave length.  it can be the coax or another counterpoise.  Although a
counterpoise has some effect on radiation pattern of a quarter wave
radiator, it is minimal.   You won't see much improvement in performance
by going above .05 wave length..  it's not worth the trouble to increase
the counterpoise length..   Fred


On 12/29/16 9:01 AM, mjisted wrote:

Looking at your text message on the elecraft board. About a half wave
length ...here is a question for you. I'm going to put up a half
wavelength of wire for the 5 mhz band. ..hyendfed can I use a quarter
wave length of counter point as a radiator ground plane. ..
The. ..G0MVP.

mjis...@btinternet.com



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Jim Brown]

Sorry Fred, I replied to what you wrote, not what you thought. Sometimes 
my mind-reading skills fail me. :)  I agree with your comments in the 
context of an end-fed half wave radiator. I modeled this in NEC several 
years ago. The result suggested a dB or so for a full radial system with 
a half wave vertical over poor ground.


73, Jim K9YC

On Thu,12/29/2016 12:50 PM, Fred Moore wrote:

Jim,  almost everyone on the list immediately noticed that I
accidentally typed 1/4 when I actually meant to type 1/2.



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Fred Moore]

Jim,  almost everyone on the list immediately noticed that I
accidentally typed 1/4 when I actually meant to type 1/2.  They most
likely noticed it because the thread has been almost 100% about 1/2 end
fed radiators.   The person I replied to specifically asked about adding
a 1/4 wave counterpoise to a EFHW antenna.  It appears that you deleted
the part of the message I was replying to and only kept the portion you
wanted everyone to see..

My response (this post) has nothing to do with my miss-type (we all oops
sometimes)  it has 100% to do with making sure you have not confused
anyone on the list into thinking an EFHW is the same as a 1/4 wave
radiator..

BTW I 100% agree with everything you said about 1/4 wave radiators..  I
absolutely do not agree that ground losses are the same on 1/2 wave
radiators as they are on 1/4 wave radiators.. Discussions about current
node locations can be had another day..

Keep spreading accurate knowledge, everyone needs it, just make sure the
knowledge you spread applies to the subject.. otherwise it creates even
more confusion.. 

Regards.. Fred


On 12/29/16 1:58 PM, Jim Brown wrote:
> Nothing in this post is true. Optimum length for a counterpoise is a
> quarter wave. Radials are a form of counterpoise, and their optimum
> length is also a quarter wave. More radials reduce ground losses.
> Failing to provide an adequate counterpoise will cause the antenna's
> return current to flow on your coax, which makes the rig hot with RF.
> That's not much of a problem with 5W, but it can be a very big deal
> with 100W or more.
>
> Of course, it does depend on what you mean by "much" and "minimal."
> Inadequate counterpoise or radial systems can easily reduce you signal
> by 6 dB. That's an S-unit, and it reduces your 5W signal to 1.25W.  I
> wouldn't call that minimal or "not much."
>
> 73, Jim K9YC
>
> On Thu,12/29/2016 7:30 AM, Fred Moore wrote:
>> With an end fed 1/4 wave you only need a counterpoise that is about .05
>> wave length.  it can be the coax or another counterpoise.  Although a
>> counterpoise has some effect on radiation pattern of a quarter wave
>> radiator, it is minimal.   You won't see much improvement in performance
>> by going above .05 wave length..  it's not worth the trouble to increase
>> the counterpoise length..
>
>
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to f...@fmeco.com
>

-- 
Fred Moore
email: f...@fmeco.com
   f...@safes.com
phone:  321-217-8699


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Fred Moore]

oops here I am typing 1/4 when the whole time I was thinking 1/2.. 
thanks for correcting me.. Fred


On 12/29/16 11:09 AM, K9MA wrote:
> I think Fred meant an end fed 1/2 wave, NOT 1/4 wave. 
>
> 73, 
>
> Scott K9MA
>
> --
>
> Scott Ellington
>
>  --- via iPad
>
>> On Dec 29, 2016, at 9:30 AM, Fred Moore <f...@fmeco.com> wrote:
>>
>> With an end fed 1/4 wave you only need a counterpoise that is about .05
>> wave length.  it can be the coax or another counterpoise.  Although a
>> counterpoise has some effect on radiation pattern of a quarter wave
>> radiator, it is minimal.   You won't see much improvement in performance
>> by going above .05 wave length..  it's not worth the trouble to increase
>> the counterpoise length..   Fred
>>
>>
>>> On 12/29/16 9:01 AM, mjisted wrote:
>>> Looking at your text message on the elecraft board. About a half wave
>>> length ...here is a question for you. I'm going to put up a half
>>> wavelength of wire for the 5 mhz band. ..hyendfed can I use a quarter
>>> wave length of counter point as a radiator ground plane. .. 
>>> The. ..G0MVP. 
>>>
>>> mjis...@btinternet.com
>>>
>>>
>>> Sent from Samsung Mobile
>>>
>>>
>>>  Original message 
>>> From: Fred Moore
>>> Date:29/12/2016 13:04 (GMT+00:00)
>>> To: elecraft@mailman.qth.net
>>> Subject: Re: [Elecraft] Small QRP antenna
>>>
>>> Don,
>>>
>>> Thank you very much, for pointing out a very common issue that gets
>>> mixed up into discussions.  Your point is so valid the random wire
>>> always seems to get mixed into the 1/2 wave discussion for some
>>> reason..  and should never be mixed together.  you are absolutely
>>> correct..   thanks again regards..  Fred
>>>
>>>
>>>> On 12/29/16 12:33 AM, Don Wilhelm wrote:
>>>> Scott,
>>>>
>>>> If the radiator is not a half wave long, it is not a "half wave".
>>>> Yes, a random length wire may work, but please do not call a random
>>>> length a half wave - the length of a half wave is quite specific.
>>>> Similarly, a quarter wavelength is a specific length at a particular
>>>> frequency.
>>>>
>>>> 73,
>>>> Don W3FPR
>>>>
>>>>> On 12/28/2016 11:20 PM, K9MA wrote:
>>>>> The counterpoise for an end fed half wave (or multiple) really doesn't
>>>>> have to be anywhere near a quarter wave long.
>>>> __
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:Elecraft@mailman.qth.net
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to f...@fmeco.com
>>>>
>>> -- 
>>> Fred Moore
>>> email: f...@fmeco.com
>>>   f...@safes.com
>>> phone:  321-217-8699
>>>
>>> __
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft@mailman.qth.net
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to mjis...@btinternet.com
>>>
>>> -- 
>>> This message has been scanned for viruses and
>>> dangerous content by *MailScanner* <http://www.mailscanner.info/>, and is
>>> believed to be clean. 
>> -- 
>> Fred Moore
>> email: f...@fmeco.com
>>   f...@safes.com
>> phone:  321-217-8699
>>
>> __
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft@mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to k...@sdellington.us

-- 
Fred Moore
email: f...@fmeco.com
   f...@safes.com
phone:  321-217-8699

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Jim Brown]

This slides for a talk I've done at Pacificon and for several ham clubs 
will tell you everything you need to know about it!


http://audiosystemsgroup.com/160MPacificon.pdf

73, Jim K9YC

On Thu,12/29/2016 8:49 AM, Richard Fjeld wrote:

With reference to below, I have a question please.  I put up a quarter
wave inverted-L for 160 meters.  My only counterpoise is the ground rods
at the base of the tower.  I wasn't expecting much, but it does so well
I'd like to add a decent counterpoise.



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Jim Brown]

Nothing in this post is true. Optimum length for a counterpoise is a 
quarter wave. Radials are a form of counterpoise, and their optimum 
length is also a quarter wave. More radials reduce ground losses. 
Failing to provide an adequate counterpoise will cause the antenna's 
return current to flow on your coax, which makes the rig hot with RF. 
That's not much of a problem with 5W, but it can be a very big deal with 
100W or more.


Of course, it does depend on what you mean by "much" and "minimal." 
Inadequate counterpoise or radial systems can easily reduce you signal 
by 6 dB. That's an S-unit, and it reduces your 5W signal to 1.25W.  I 
wouldn't call that minimal or "not much."


73, Jim K9YC

On Thu,12/29/2016 7:30 AM, Fred Moore wrote:

With an end fed 1/4 wave you only need a counterpoise that is about .05
wave length.  it can be the coax or another counterpoise.  Although a
counterpoise has some effect on radiation pattern of a quarter wave
radiator, it is minimal.   You won't see much improvement in performance
by going above .05 wave length..  it's not worth the trouble to increase
the counterpoise length..



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Mel Farrer via Elecraft]

One thing I will add that has not been commented on, is the way of feeding a 
1/2 wl wire with a 1/4 wl twin lead. Where one side of the twin lead at the top 
is connected to the 1/2 wl wire.  You can feed the twin lead at the bottom with 
a 1:1 choke and you don't need a ground. Then for the upper bands, tie the twin 
lead together and feed it against your counterpoise.  The twin lead does not 
have to be completely vertical either.  

Mel, K6KBE


  From: Don Wilhelm <donw...@embarqmail.com>
 To: Richard Fjeld <rpfj...@outlook.com>; "elecraft@mailman.qth.net" 
<elecraft@mailman.qth.net> 
 Sent: Thursday, December 29, 2016 9:05 AM
 Subject: Re: [Elecraft] Small QRP antenna
   
Dick,

With buried radials, they do not have to be 1/4 wave long, and a single 
one will probably not make much difference over your ground rod.
What you want to accomplish is a "ground screen", which means many short 
(about 1/8 wavelength) close to the base of the radiator and a few 
extending out further (to 1/4 or 1/2 wavelength).

Ground conductivity plays a great part in buried radials, and what you 
are trying to accomplish is to increase the ground conductivity in the 
area at the base of the antenna.

If you were instead using elevated radials, they would have to be 
resonant - think of the various "ground plane" antennas that have been 
published - 1/4 wave radiator plus 2 or 4 1/4 wave radials.
Buried radials do not have to be resonant, elevated radials must be 
resonant.  The ground effects will alter the resonance of buried radials 
while radials in the air are a part of the total antenna resonance.

73,
Don W3FPR

On 12/29/2016 11:49 AM, Richard Fjeld wrote:
> With reference to below, I have a question please.  I put up a quarter
> wave inverted-L for 160 meters.  My only counterpoise is the ground rods
> at the base of the tower.  I wasn't expecting much, but it does so well
> I'd like to add a decent counterpoise.
>
> If I bury a quarter wave wire, would it be best to put it under the
> Ariel wire, or opposite from it?
> Thanks in advance,
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to farrerfo...@yahoo.com


   
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Mike Morrow]

Don wrote:

> A 1/2 wave radiator fed at the end theoretically does not need
> any counterpoise, but in practice it does - but only needs to
> be about 0.05 wavelength long.
>
> Refer to some antenna books (the ARRL has a good one) or the ARRL 
> Handbook for good information about basic antennas.

The concise clarity of Don's input to this thread is refreshing.  Such seem to 
occur rarely in ham discussions about antennas.

With respect to classical end-fed half-wave antennas, I think of the end-fed 
Zepp[elin] and the common VHF J-poles.

Mike / KK5F
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Don Wilhelm]

Dick,

With buried radials, they do not have to be 1/4 wave long, and a single 
one will probably not make much difference over your ground rod.
What you want to accomplish is a "ground screen", which means many short 
(about 1/8 wavelength) close to the base of the radiator and a few 
extending out further (to 1/4 or 1/2 wavelength).


Ground conductivity plays a great part in buried radials, and what you 
are trying to accomplish is to increase the ground conductivity in the 
area at the base of the antenna.


If you were instead using elevated radials, they would have to be 
resonant - think of the various "ground plane" antennas that have been 
published - 1/4 wave radiator plus 2 or 4 1/4 wave radials.
Buried radials do not have to be resonant, elevated radials must be 
resonant.  The ground effects will alter the resonance of buried radials 
while radials in the air are a part of the total antenna resonance.


73,
Don W3FPR

On 12/29/2016 11:49 AM, Richard Fjeld wrote:

With reference to below, I have a question please.  I put up a quarter
wave inverted-L for 160 meters.  My only counterpoise is the ground rods
at the base of the tower.  I wasn't expecting much, but it does so well
I'd like to add a decent counterpoise.

If I bury a quarter wave wire, would it be best to put it under the
Ariel wire, or opposite from it?
Thanks in advance,

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Richard Fjeld]

With reference to below, I have a question please.  I put up a quarter 
wave inverted-L for 160 meters.  My only counterpoise is the ground rods 
at the base of the tower.  I wasn't expecting much, but it does so well 
I'd like to add a decent counterpoise.

If I bury a quarter wave wire, would it be best to put it under the 
Ariel wire, or opposite from it?
Thanks in advance,
Dick, n0ce


On 12/29/2016 10:16 AM, Don Wilhelm wrote:
> I think this is mixing up 1/2 wave radiators and 1/4 wave radiators.
> To be resonant, a 1/4 wave wire needs another 1/4 wave "counterpoise" 
> - think of a center fed dipole - it has 1/4 wave on each side whether 
> one side is a monopole (vertical) and the other 1/4 wave is an 
> elevated radial or buried radials of indeterminate length, or whether 
> it is a dipole with the center in the air.
>
> A 1/2 wave radiator fed at the end theoretically does not need any 
> counterpoise, but in practice it does - but only needs to be about 
> 0.05 wavelength long.
>
> Refer to some antenna books (the ARRL has a good one) or the ARRL 
> Handbook for good information about basic antennas.
>
> 73,
> Don W3FPR
>
> On 12/29/2016 10:30 AM, Fred Moore wrote:
>> With an end fed 1/4 wave you only need a counterpoise that is about .05
>> wave length.  it can be the coax or another counterpoise. Although a
>> counterpoise has some effect on radiation pattern of a quarter wave
>> radiator, it is minimal.   You won't see much improvement in performance
>> by going above .05 wave length..  it's not worth the trouble to increase
>> the counterpoise length..   Fred
>>
>>
>> On 12/29/16 9:01 AM, mjisted wrote:
>>> Looking at your text message on the elecraft board. About a half wave
>>> length ...here is a question for you. I'm going to put up a half
>>> wavelength of wire for the 5 mhz band. ..hyendfed can I use a quarter
>>> wave length of counter point as a radiator ground plane. ..
>>> The. ..G0MVP.
>>>
>>> mjis...@btinternet.com
>>>
>>>
>>> Sent from Samsung Mobile
>>>
>>>
>>>  Original message 
>>> From: Fred Moore
>>> Date:29/12/2016 13:04 (GMT+00:00)
>>> To: elecraft@mailman.qth.net
>>> Subject: Re: [Elecraft] Small QRP antenna
>>>
>>> Don,
>>>
>>> Thank you very much, for pointing out a very common issue that gets
>>> mixed up into discussions.  Your point is so valid the random wire
>>> always seems to get mixed into the 1/2 wave discussion for some
>>> reason..  and should never be mixed together.  you are absolutely
>>> correct..   thanks again regards..  Fred
>>>
>>>
>>> On 12/29/16 12:33 AM, Don Wilhelm wrote:
>>>> Scott,
>>>>
>>>> If the radiator is not a half wave long, it is not a "half wave".
>>>> Yes, a random length wire may work, but please do not call a random
>>>> length a half wave - the length of a half wave is quite specific.
>>>> Similarly, a quarter wavelength is a specific length at a particular
>>>> frequency.
>>>>
>>>> 73,
>>>> Don W3FPR
>>>>
>>>> On 12/28/2016 11:20 PM, K9MA wrote:
>>>>> The counterpoise for an end fed half wave (or multiple) really 
>>>>> doesn't
>>>>> have to be anywhere near a quarter wave long.
>>>> __
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:Elecraft@mailman.qth.net
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to f...@fmeco.com
>>>>
>>>
>>> -- 
>>> Fred Moore
>>> email: f...@fmeco.com
>>>f...@safes.com
>>> phone:  321-217-8699
>>>
>>> __
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft@mailman.qth.net
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to mjis...@btinternet.com
>>>
>>> -- 
>>> This message has been scanned for viruses and
>>> dangerous content by *MailScanner* <http://www.mailscanner.info/>, 
>>> and is
>>> believed to be clean.
>>
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to rpfj...@outlook.com

-- 

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Don Wilhelm]

I think this is mixing up 1/2 wave radiators and 1/4 wave radiators.
To be resonant, a 1/4 wave wire needs another 1/4 wave "counterpoise" - 
think of a center fed dipole - it has 1/4 wave on each side whether one 
side is a monopole (vertical) and the other 1/4 wave is an elevated 
radial or buried radials of indeterminate length, or whether it is a 
dipole with the center in the air.


A 1/2 wave radiator fed at the end theoretically does not need any 
counterpoise, but in practice it does - but only needs to be about 0.05 
wavelength long.


Refer to some antenna books (the ARRL has a good one) or the ARRL 
Handbook for good information about basic antennas.


73,
Don W3FPR

On 12/29/2016 10:30 AM, Fred Moore wrote:

With an end fed 1/4 wave you only need a counterpoise that is about .05
wave length.  it can be the coax or another counterpoise.  Although a
counterpoise has some effect on radiation pattern of a quarter wave
radiator, it is minimal.   You won't see much improvement in performance
by going above .05 wave length..  it's not worth the trouble to increase
the counterpoise length..   Fred


On 12/29/16 9:01 AM, mjisted wrote:

Looking at your text message on the elecraft board. About a half wave
length ...here is a question for you. I'm going to put up a half
wavelength of wire for the 5 mhz band. ..hyendfed can I use a quarter
wave length of counter point as a radiator ground plane. ..
The. ..G0MVP.

mjis...@btinternet.com


Sent from Samsung Mobile


 Original message 
From: Fred Moore
Date:29/12/2016 13:04 (GMT+00:00)
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna

Don,

Thank you very much, for pointing out a very common issue that gets
mixed up into discussions.  Your point is so valid the random wire
always seems to get mixed into the 1/2 wave discussion for some
reason..  and should never be mixed together.  you are absolutely
correct..   thanks again regards..  Fred


On 12/29/16 12:33 AM, Don Wilhelm wrote:

Scott,

If the radiator is not a half wave long, it is not a "half wave".
Yes, a random length wire may work, but please do not call a random
length a half wave - the length of a half wave is quite specific.
Similarly, a quarter wavelength is a specific length at a particular
frequency.

73,
Don W3FPR

On 12/28/2016 11:20 PM, K9MA wrote:

The counterpoise for an end fed half wave (or multiple) really doesn't
have to be anywhere near a quarter wave long.

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to f...@fmeco.com



--
Fred Moore
email: f...@fmeco.com
   f...@safes.com
phone:  321-217-8699

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to mjis...@btinternet.com

--
This message has been scanned for viruses and
dangerous content by *MailScanner* <http://www.mailscanner.info/>, and is
believed to be clean.



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[K9MA]

I think Fred meant an end fed 1/2 wave, NOT 1/4 wave. 

73, 

Scott K9MA

--

Scott Ellington

 --- via iPad

> On Dec 29, 2016, at 9:30 AM, Fred Moore <f...@fmeco.com> wrote:
> 
> With an end fed 1/4 wave you only need a counterpoise that is about .05
> wave length.  it can be the coax or another counterpoise.  Although a
> counterpoise has some effect on radiation pattern of a quarter wave
> radiator, it is minimal.   You won't see much improvement in performance
> by going above .05 wave length..  it's not worth the trouble to increase
> the counterpoise length..   Fred
> 
> 
>> On 12/29/16 9:01 AM, mjisted wrote:
>> Looking at your text message on the elecraft board. About a half wave
>> length ...here is a question for you. I'm going to put up a half
>> wavelength of wire for the 5 mhz band. ..hyendfed can I use a quarter
>> wave length of counter point as a radiator ground plane. .. 
>> The. ..G0MVP. 
>> 
>> mjis...@btinternet.com
>> 
>> 
>> Sent from Samsung Mobile
>> 
>> 
>>  Original message --------
>> From: Fred Moore
>> Date:29/12/2016 13:04 (GMT+00:00)
>> To: elecraft@mailman.qth.net
>> Subject: Re: [Elecraft] Small QRP antenna
>> 
>> Don,
>> 
>> Thank you very much, for pointing out a very common issue that gets
>> mixed up into discussions.  Your point is so valid the random wire
>> always seems to get mixed into the 1/2 wave discussion for some
>> reason..  and should never be mixed together.  you are absolutely
>> correct..   thanks again regards..  Fred
>> 
>> 
>>> On 12/29/16 12:33 AM, Don Wilhelm wrote:
>>> Scott,
>>> 
>>> If the radiator is not a half wave long, it is not a "half wave".
>>> Yes, a random length wire may work, but please do not call a random
>>> length a half wave - the length of a half wave is quite specific.
>>> Similarly, a quarter wavelength is a specific length at a particular
>>> frequency.
>>> 
>>> 73,
>>> Don W3FPR
>>> 
>>>> On 12/28/2016 11:20 PM, K9MA wrote:
>>>> The counterpoise for an end fed half wave (or multiple) really doesn't
>>>> have to be anywhere near a quarter wave long.
>>> __
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft@mailman.qth.net
>>> 
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to f...@fmeco.com
>>> 
>> 
>> -- 
>> Fred Moore
>> email: f...@fmeco.com
>>   f...@safes.com
>> phone:  321-217-8699
>> 
>> __
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft@mailman.qth.net
>> 
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to mjis...@btinternet.com
>> 
>> -- 
>> This message has been scanned for viruses and
>> dangerous content by *MailScanner* <http://www.mailscanner.info/>, and is
>> believed to be clean. 
> 
> -- 
> Fred Moore
> email: f...@fmeco.com
>   f...@safes.com
> phone:  321-217-8699
> 
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to k...@sdellington.us
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Fred Moore]

With an end fed 1/4 wave you only need a counterpoise that is about .05
wave length.  it can be the coax or another counterpoise.  Although a
counterpoise has some effect on radiation pattern of a quarter wave
radiator, it is minimal.   You won't see much improvement in performance
by going above .05 wave length..  it's not worth the trouble to increase
the counterpoise length..   Fred


On 12/29/16 9:01 AM, mjisted wrote:
> Looking at your text message on the elecraft board. About a half wave
> length ...here is a question for you. I'm going to put up a half
> wavelength of wire for the 5 mhz band. ..hyendfed can I use a quarter
> wave length of counter point as a radiator ground plane. .. 
> The. ..G0MVP. 
>
> mjis...@btinternet.com
>
>
> Sent from Samsung Mobile
>
>
>  Original message 
> From: Fred Moore
> Date:29/12/2016 13:04 (GMT+00:00)
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] Small QRP antenna
>
> Don,
>
> Thank you very much, for pointing out a very common issue that gets
> mixed up into discussions.  Your point is so valid the random wire
> always seems to get mixed into the 1/2 wave discussion for some
> reason..  and should never be mixed together.  you are absolutely
> correct..   thanks again regards..  Fred
>
>
> On 12/29/16 12:33 AM, Don Wilhelm wrote:
> > Scott,
> >
> > If the radiator is not a half wave long, it is not a "half wave".
> > Yes, a random length wire may work, but please do not call a random
> > length a half wave - the length of a half wave is quite specific.
> > Similarly, a quarter wavelength is a specific length at a particular
> > frequency.
> >
> > 73,
> > Don W3FPR
> >
> > On 12/28/2016 11:20 PM, K9MA wrote:
> >> The counterpoise for an end fed half wave (or multiple) really doesn't
> >> have to be anywhere near a quarter wave long.
> > __
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft@mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to f...@fmeco.com
> >
>
> -- 
> Fred Moore
> email: f...@fmeco.com
>f...@safes.com
> phone:  321-217-8699
>
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to mjis...@btinternet.com
>
> -- 
> This message has been scanned for viruses and
> dangerous content by *MailScanner* <http://www.mailscanner.info/>, and is
> believed to be clean. 

-- 
Fred Moore
email: f...@fmeco.com
   f...@safes.com
phone:  321-217-8699

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[mjisted]

Looking at your text message on the elecraft board. About a half wave length 
...here is a question for you. I'm going to put up a half wavelength of wire 
for the 5 mhz band. ..hyendfed can I use a quarter wave length of counter point 
as a radiator ground plane. .. 
The. ..G0MVP. 

mjis...@btinternet.com


Sent from Samsung Mobile

 Original message From: Fred Moore 
<f...@fmeco.com> Date:29/12/2016  13:04  (GMT+00:00) To: 
elecraft@mailman.qth.net Subject: Re: [Elecraft] Small QRP antenna 

Don,

Thank you very much, for pointing out a very common issue that gets
mixed up into discussions.  Your point is so valid the random wire
always seems to get mixed into the 1/2 wave discussion for some
reason..  and should never be mixed together.  you are absolutely
correct..   thanks again regards..  Fred


On 12/29/16 12:33 AM, Don Wilhelm wrote:
> Scott,
>
> If the radiator is not a half wave long, it is not a "half wave".
> Yes, a random length wire may work, but please do not call a random
> length a half wave - the length of a half wave is quite specific.
> Similarly, a quarter wavelength is a specific length at a particular
> frequency.
>
> 73,
> Don W3FPR
>
> On 12/28/2016 11:20 PM, K9MA wrote:
>> The counterpoise for an end fed half wave (or multiple) really doesn't
>> have to be anywhere near a quarter wave long.
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to f...@fmeco.com
>

-- 
Fred Moore
email: f...@fmeco.com
   f...@safes.com
phone:  321-217-8699

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to mjis...@btinternet.com
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Fred Moore]

Don,

Thank you very much, for pointing out a very common issue that gets
mixed up into discussions.  Your point is so valid the random wire
always seems to get mixed into the 1/2 wave discussion for some
reason..  and should never be mixed together.  you are absolutely
correct..   thanks again regards..  Fred


On 12/29/16 12:33 AM, Don Wilhelm wrote:
> Scott,
>
> If the radiator is not a half wave long, it is not a "half wave".
> Yes, a random length wire may work, but please do not call a random
> length a half wave - the length of a half wave is quite specific.
> Similarly, a quarter wavelength is a specific length at a particular
> frequency.
>
> 73,
> Don W3FPR
>
> On 12/28/2016 11:20 PM, K9MA wrote:
>> The counterpoise for an end fed half wave (or multiple) really doesn't
>> have to be anywhere near a quarter wave long.
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to f...@fmeco.com
>

-- 
Fred Moore
email: f...@fmeco.com
   f...@safes.com
phone:  321-217-8699

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Don Wilhelm]

Scott,

If the radiator is not a half wave long, it is not a "half wave".
Yes, a random length wire may work, but please do not call a random 
length a half wave - the length of a half wave is quite specific.
Similarly, a quarter wavelength is a specific length at a particular 
frequency.


73,
Don W3FPR

On 12/28/2016 11:20 PM, K9MA wrote:

The counterpoise for an end fed half wave (or multiple) really doesn't
have to be anywhere near a quarter wave long.

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[K9MA]

The counterpoise for an end fed half wave (or multiple) really doesn't 
have to be anywhere near a quarter wave long.  The feedpoint impedance 
is something over 2000 Ohms.  I use a single wire about 8 feet long, 
which seems to work fine.  NEC agrees.  My simple test is to get it 
perfectly matched, then put my hand on the tuner box.  If the SWR 
doesn't change, the counterpoise is adequate.


I did recently try the 40 M half wave on 80, with two quarter wave 
radials.  There was, of course, some "rf in the shack", but it didn't 
cause any problems, and the antenna seemed to work fairly well, 
especially considering that it was in the bottom of Death Valley.


73,

Scott  K9MA

On 12/28/2016 18:14, Fred Jensen wrote:
Ron is correct ... however my experience is that the rig, headphone 
cable, power cable from the battery, and me [holding the KX1] is more 
than sufficient.  For mine at home, it is fed with about 25 ft of 
coax, the shield of which serves that purpose.


If you attempt to model it with NEC-2, and all you care about are the 
radiation patterns, you don't need a counterpoise in the model.  While 
NEC-2 *really* doesn't like a source connected to the end of a wire, 
it only affects the source impedance values. If you want those to be 
reasonably accurate and real, a short wire is necessary ... anything 
over a few feet seems to work just fine and is in no way critical.


Fred K6DGW
Sparks NV DM09dn
Washoe County

On 12/28/2016 3:43 PM, Ron D'Eau Claire wrote:
While the efficiency as a radiator of a half wave end fed wire is 
relatively
unaffected by the "ground" return, some sort of "ground" is needed to 
keep

the whole rig from floating up to the RF potential at the end of the
antenna. Often a hunk of wire roughly 1/4 wave long thrown on the 
ground is

adequate.

I too have had excellent results with them.

73 Ron AC7AC

-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of 
Fred

Jensen
Sent: Wednesday, December 28, 2016 12:57 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna

The Summits On The Air crowd, at least one of whom "runs" up 
mountains, has
had very good luck with end-fed half-waves.  The transformer weighs 
next to
nothing, and the rest is just wire. Requires no counterpoise, very 
ground

insensitive since it's fed at a voltage node.  Also because of that, you
need no coax, just an adapter between rig and transformer.
The higher you can get the middle [current node] the better, but it will
work very well with just about any elevation on the far end.

For 40, it's about 67 ft of wire, and is a full-wave on 20 and will work
well there.  My KX1, when I still had it, had no problem finding a 
match.
My HOA-Stealth here at home is an 80-10 EFHW strung about 6 ft high 
along

the top of a wooden fence.  Works surprisingly well.

Fred K6DGW
Sparks NV DM09dn
Washoe County

--Northern California Contest Club
--CU in the Cal QSO Party
--7-8 Oct 2017

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html 
Message

delivered to r...@elecraft.com




--
Scott  K9MA

k...@sdellington.us

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Fred Jensen]

Ron is correct ... however my experience is that the rig, headphone 
cable, power cable from the battery, and me [holding the KX1] is more 
than sufficient.  For mine at home, it is fed with about 25 ft of coax, 
the shield of which serves that purpose.


If you attempt to model it with NEC-2, and all you care about are the 
radiation patterns, you don't need a counterpoise in the model.  While 
NEC-2 *really* doesn't like a source connected to the end of a wire, it 
only affects the source impedance values.  If you want those to be 
reasonably accurate and real, a short wire is necessary ... anything 
over a few feet seems to work just fine and is in no way critical.


Fred K6DGW
Sparks NV DM09dn
Washoe County

On 12/28/2016 3:43 PM, Ron D'Eau Claire wrote:

While the efficiency as a radiator of a half wave end fed wire is relatively
unaffected by the "ground" return, some sort of "ground" is needed to keep
the whole rig from floating up to the RF potential at the end of the
antenna. Often a hunk of wire roughly 1/4 wave long thrown on the ground is
adequate.

I too have had excellent results with them.

73 Ron AC7AC

-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Fred
Jensen
Sent: Wednesday, December 28, 2016 12:57 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna

The Summits On The Air crowd, at least one of whom "runs" up mountains, has
had very good luck with end-fed half-waves.  The transformer weighs next to
nothing, and the rest is just wire. Requires no counterpoise, very ground
insensitive since it's fed at a voltage node.  Also because of that, you
need no coax, just an adapter between rig and transformer.
The higher you can get the middle [current node] the better, but it will
work very well with just about any elevation on the far end.

For 40, it's about 67 ft of wire, and is a full-wave on 20 and will work
well there.  My KX1, when I still had it, had no problem finding a match.
My HOA-Stealth here at home is an 80-10 EFHW strung about 6 ft high along
the top of a wooden fence.  Works surprisingly well.

Fred K6DGW
Sparks NV DM09dn
Washoe County

--Northern California Contest Club
--CU in the Cal QSO Party
--7-8 Oct 2017

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html Message
delivered to r...@elecraft.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to k6...@foothill.net


-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2016.0.7924 / Virus Database: 4739/13664 - Release Date: 12/28/16




__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Ron D'Eau Claire]

While the efficiency as a radiator of a half wave end fed wire is relatively
unaffected by the "ground" return, some sort of "ground" is needed to keep
the whole rig from floating up to the RF potential at the end of the
antenna. Often a hunk of wire roughly 1/4 wave long thrown on the ground is
adequate. 

I too have had excellent results with them. 

73 Ron AC7AC

-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Fred
Jensen
Sent: Wednesday, December 28, 2016 12:57 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna

The Summits On The Air crowd, at least one of whom "runs" up mountains, has
had very good luck with end-fed half-waves.  The transformer weighs next to
nothing, and the rest is just wire. Requires no counterpoise, very ground
insensitive since it's fed at a voltage node.  Also because of that, you
need no coax, just an adapter between rig and transformer.  
The higher you can get the middle [current node] the better, but it will
work very well with just about any elevation on the far end.

For 40, it's about 67 ft of wire, and is a full-wave on 20 and will work
well there.  My KX1, when I still had it, had no problem finding a match.
My HOA-Stealth here at home is an 80-10 EFHW strung about 6 ft high along
the top of a wooden fence.  Works surprisingly well.

Fred K6DGW
Sparks NV DM09dn
Washoe County

--Northern California Contest Club
--CU in the Cal QSO Party
--7-8 Oct 2017

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html Message
delivered to r...@elecraft.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[K9MA]

If you're willing to spend a little more for less weight, this outfit 
has carbon-fiber fishing poles of various lengths:


allfishingbuy.com

The one I have extends to 38 feet, weighs about 500 grams, and collapses 
to 34 inches.  The tip is pretty floppy, but it holds up my AWG 26 
wire.  Stiffer ones are available, but they're heavier, though sometimes 
cheaper.  You do have to keep the wire away from the pole, as it's 
conductive.


Never, ever lay it on the ground when some klutz can step on it, though.

73,

Scott  K9MA

On 12/28/2016 15:47, Chris Tate - N6WM wrote:

I just ordered a number of options from SotaBeams in the UK to compliment my 
KX2.

http://www.sotabeams.co.uk/antennas-hf/

Small and sometimes conveniently packed options make taking the fully qrv ready 
rig to the Caribbean very easy.

Even as a big gun contester I am having alot of fun with the little feature packed 
KX2 and its portable potential.   they also sell a telescopic 30 ft fiberglass mast 
that breaks down to 26".  amazing what you can fit in a backpack these days ;-).

Chris
N6WM



From: Elecraft [elecraft-boun...@mailman.qth.net] on behalf of K9MA 
[k...@sdellington.us]
Sent: Wednesday, December 28, 2016 1:32 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna

I've had good luck with the end fed 40 M half wave, too.  I use it with
the KX1 to do CWT's on bicycle tours (in warmer weather).  While the
transformer and ATU apparently works, I wanted a really good match to
maximize output power, so I built a small QRP tuner for it:

http://sdellington.us/hr/EFHW_Tuner2.pdf

Most of the parts come from the Pacific Antenna BLT+ kit, which they
were willing to sell me without the case.

73,

Scott  K9MA



On 12/28/2016 14:56, Fred Jensen wrote:

The Summits On The Air crowd, at least one of whom "runs" up
mountains, has had very good luck with end-fed half-waves.  The
transformer weighs next to nothing, and the rest is just wire.
Requires no counterpoise, very ground insensitive since it's fed at a
voltage node.  Also because of that, you need no coax, just an adapter
between rig and transformer.  The higher you can get the middle
[current node] the better, but it will work very well with just about
any elevation on the far end.

For 40, it's about 67 ft of wire, and is a full-wave on 20 and will
work well there.  My KX1, when I still had it, had no problem finding
a match.  My HOA-Stealth here at home is an 80-10 EFHW strung about 6
ft high along the top of a wooden fence.  Works surprisingly well.

Fred K6DGW
Sparks NV DM09dn
Washoe County

--Northern California Contest Club
--CU in the Cal QSO Party
--7-8 Oct 2017

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to k...@sdellington.us


--
Scott  K9MA

k...@sdellington.us

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to ct...@ewnetinc.com



--
Scott  K9MA

k...@sdellington.us

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Chris Tate - N6WM]

I just ordered a number of options from SotaBeams in the UK to compliment my 
KX2.

http://www.sotabeams.co.uk/antennas-hf/

Small and sometimes conveniently packed options make taking the fully qrv ready 
rig to the Caribbean very easy.

Even as a big gun contester I am having alot of fun with the little feature 
packed KX2 and its portable potential.   they also sell a telescopic 30 ft 
fiberglass mast that breaks down to 26".  amazing what you can fit in a 
backpack these days ;-).  

Chris
N6WM



From: Elecraft [elecraft-boun...@mailman.qth.net] on behalf of K9MA 
[k...@sdellington.us]
Sent: Wednesday, December 28, 2016 1:32 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna

I've had good luck with the end fed 40 M half wave, too.  I use it with
the KX1 to do CWT's on bicycle tours (in warmer weather).  While the
transformer and ATU apparently works, I wanted a really good match to
maximize output power, so I built a small QRP tuner for it:

http://sdellington.us/hr/EFHW_Tuner2.pdf

Most of the parts come from the Pacific Antenna BLT+ kit, which they
were willing to sell me without the case.

73,

Scott  K9MA



On 12/28/2016 14:56, Fred Jensen wrote:
> The Summits On The Air crowd, at least one of whom "runs" up
> mountains, has had very good luck with end-fed half-waves.  The
> transformer weighs next to nothing, and the rest is just wire.
> Requires no counterpoise, very ground insensitive since it's fed at a
> voltage node.  Also because of that, you need no coax, just an adapter
> between rig and transformer.  The higher you can get the middle
> [current node] the better, but it will work very well with just about
> any elevation on the far end.
>
> For 40, it's about 67 ft of wire, and is a full-wave on 20 and will
> work well there.  My KX1, when I still had it, had no problem finding
> a match.  My HOA-Stealth here at home is an 80-10 EFHW strung about 6
> ft high along the top of a wooden fence.  Works surprisingly well.
>
> Fred K6DGW
> Sparks NV DM09dn
> Washoe County
>
> --Northern California Contest Club
> --CU in the Cal QSO Party
> --7-8 Oct 2017
>
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to k...@sdellington.us


--
Scott  K9MA

k...@sdellington.us

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to ct...@ewnetinc.com
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[K9MA]

I've had good luck with the end fed 40 M half wave, too.  I use it with 
the KX1 to do CWT's on bicycle tours (in warmer weather).  While the 
transformer and ATU apparently works, I wanted a really good match to 
maximize output power, so I built a small QRP tuner for it:


http://sdellington.us/hr/EFHW_Tuner2.pdf

Most of the parts come from the Pacific Antenna BLT+ kit, which they 
were willing to sell me without the case.


73,

Scott  K9MA



On 12/28/2016 14:56, Fred Jensen wrote:
The Summits On The Air crowd, at least one of whom "runs" up 
mountains, has had very good luck with end-fed half-waves.  The 
transformer weighs next to nothing, and the rest is just wire. 
Requires no counterpoise, very ground insensitive since it's fed at a 
voltage node.  Also because of that, you need no coax, just an adapter 
between rig and transformer.  The higher you can get the middle 
[current node] the better, but it will work very well with just about 
any elevation on the far end.


For 40, it's about 67 ft of wire, and is a full-wave on 20 and will 
work well there.  My KX1, when I still had it, had no problem finding 
a match.  My HOA-Stealth here at home is an 80-10 EFHW strung about 6 
ft high along the top of a wooden fence.  Works surprisingly well.


Fred K6DGW
Sparks NV DM09dn
Washoe County

--Northern California Contest Club
--CU in the Cal QSO Party
--7-8 Oct 2017

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to k...@sdellington.us



--
Scott  K9MA

k...@sdellington.us

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna

[Fred Jensen]

The Summits On The Air crowd, at least one of whom "runs" up mountains, 
has had very good luck with end-fed half-waves.  The transformer weighs 
next to nothing, and the rest is just wire. Requires no counterpoise, 
very ground insensitive since it's fed at a voltage node.  Also because 
of that, you need no coax, just an adapter between rig and transformer.  
The higher you can get the middle [current node] the better, but it will 
work very well with just about any elevation on the far end.


For 40, it's about 67 ft of wire, and is a full-wave on 20 and will work 
well there.  My KX1, when I still had it, had no problem finding a 
match.  My HOA-Stealth here at home is an 80-10 EFHW strung about 6 ft 
high along the top of a wooden fence.  Works surprisingly well.


Fred K6DGW
Sparks NV DM09dn
Washoe County

--Northern California Contest Club
--CU in the Cal QSO Party
--7-8 Oct 2017

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

[Elecraft] Small QRP antenna

[kl7cw]

For about 50 years my usual portable antenna was a linked dipole, coax fed, and 
usually rigged as an inverted V for 40, 30, and 20 meters.  Performance was 
usually very good especially if the apex was at least something like 25 feet.  
However, this was heavy, took too much time to set up, and often there was not 
enough room in a park or campground.  Often the set up was just not worth the 
trouble after a long day of backpacking, etc.  However about 12 years ago when 
I got my KX1 with internal tuner, I found out I could make many good QSO’s on 
40, 30 and 20 meters with a simple 26 ft. wire in a tree, bush, vertical, 
sloped, or whatever and a 17 ft. wire or two laying on the ground. Many more 
QSO’s since set up was so easy, however not nearly as good as the inverted V.  
Now when I travel I usually just take a 26 ft piece of wire, two 17 ft 
counterpoise wires, and about an 8 ft. long wire with a big clip on the end.  
Sometimes counterpoise wires are not convenient to lay out, so I just clip onto 
a metal picnic table frame, chain link fence, or whatever for a ground 
(counterpoise) and it seems to be acceptable.  At other times I extend my 26 ft 
wire or counterpoise with the 8 ft wire for a better tune or performance on 40 
meters, especially if the counterpoise wires are elevated even slightly.  If 
space and supports are limited, I have thrown one 17 ft wire up over short 
trees or bushes of only perhaps 10 ft in height, and this inverted u antenna 
has even worked some DX on 20 meters (the other 17 ft wire is a counterpoise).  
I usually I like two counterpoise wires since models show a slight null if only 
one counterpoise wire is used.  
There are better portable antennas than the 26 ft wire, however it seems to be 
a winner when you consider weight, ease of set up, cost, and performance.  This 
is usually the only antenna I carry when I go to Europe or the UK where 
millions of folks live within a few hundred miles.  However when I operate 
portable from Alaska or other very remote locations, or especially in a 
contest, then sometimes better antennas are worth the effort and weight even 
for this old backpacker.  Do investigate end fed half wave antennas…many 
portable QRP operators go this route.  Your rig runs much more power than my 
kx1 and has a better antenna tuner, so you should have even more success than I 
have had with my 2 watts.  
  Cheers,   Rick   KL7CW

Sent from Mail for Windows 10

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna question

[Michael Babineau]

If you want to cover 80m through 10m with a single wire try something in the 
range of 84 to 86 feet. 
This length is not a multiple of a half wave on any of the ham bands so it will 
present a reasonable impedance 
that can be be matched with a tuner and not surprisingly this is the W3EDP 
length. 

If you don’t care about 80m then the suggested 26 to 29 foot wire will work 
great (I personally recommend 28 to 29 feet as I have found that 
a 26 foot wire is sometimes a bit harder to match on 40m depending on how it is 
deployed). 

Ground radial length isn’t critical, but i suggest at least 1/8 wave on the 
lowest frequency of operation and more is better.
I normally use 5 radials made out of a 20 foot length of 5 conductor computer 
ribbon cable with all wires shorted together at
one end and connected to a single banana plug. You then unzip the wires from 
the end opposite the banana plug so that you only have
about 4 feet at the banana plug end that is still ‘zipped”.  This makes it 
convenient to route the radial wires off  a picnic table etc. before they
splay out on the ground.  When packing up I just pull all of the wires straight 
together and clip them together at the unzipped end with an IKEA 
bag clip before rolling them up.  I use a 5 conductor cable as that is about my 
patience limit for radial deployment ;-) 

Cheers

Michael VE3WMB / VA2NB (KX1, K1, K2) 

>From: Walter Underwood <wun...@wunderwood.org <mailto:wun...@wunderwood.org>>
>Subject: Re: [Elecraft] Small QRP antenna question
>Date: December 27, 2016 at 2:12:09 AM GMT-5
>To: Elecraft Reflector Reflector <elecraft@mailman.qth.net 
><mailto:elecraft@mailman.qth.net>>


>For 80 meters, try a 53 foot wire in the air. For 40 meters and up, try a wire 
>26 to 29 feet long.

>I use a 16 foot wire laying on the ground. That length either isn’t critical, 
>or changes electrical length due to capacitance to RF ground at every site. Or 
>both. Whatever, the ATU seems to deal >with it.

>I assume you have the ATU.

>I have been using camping clothesline reels for the wire, but they don’t wind 
>up very smoothly. I just got some “midi” wire winders from SOTAbeams 
>(http://www.sotabeams.co.uk/midi->winders/ 
><http://www.sotabeams.co.uk/midi-%3Ewinders/><http://www.sotabeams.co.uk/midi-winders/
> <http://www.sotabeams.co.uk/midi-winders/>>). The regular winders are longer 
>than my KX3. Haven’t used them yet.

>wunder
>K6WRU
>Walter Underwood
>CM87wj
>http://observer.wunderwood.org/ <http://observer.wunderwood.org/> (my blog)
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com

Re: [Elecraft] Small QRP antenna question

[Walter Underwood]

For 80 meters, try a 53 foot wire in the air. For 40 meters and up, try a wire 
26 to 29 feet long.

I use a 16 foot wire laying on the ground. That length either isn’t critical, 
or changes electrical length due to capacitance to RF ground at every site. Or 
both. Whatever, the ATU seems to deal with it.

I assume you have the ATU.

I have been using camping clothesline reels for the wire, but they don’t wind 
up very smoothly. I just got some “midi” wire winders from SOTAbeams 
(http://www.sotabeams.co.uk/midi-winders/ 
). The regular winders are longer 
than my KX3. Haven’t used them yet.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Dec 26, 2016, at 10:33 PM, Terry Brown  wrote:
> 
> Hello Group,
> 
> 
> 
> I currently use a doublet about 63 ft. on each side feeding 300 ohm twin
> lead line into an Elecraft balun, then coax to my KX3.
> 
> 
> 
> I am going to be going to New Zealand for about three weeks during February,
> and I am seriously considering taking my KX3 with me and operate N7TB/ZL.  I
> just don't want to take the doublet because of size.  I have one of the BNC
> to binding posts adapters for my KX3, and that seems like the best solution,
> I just don't know how long my antenna wire should be, or the counterpoise.
> I would appreciate any suggestions.  I would like to have the ability to
> operate 80, 40, 30, 20, but I could get by without 80 meters.  
> 
> 
> 
> I would also be interested to find out from any Kiwi operators what the
> current band conditions are in NZ.  It will be later in the Summer in the
> Southern Hemisphere when I am there, so I would hope conditions on the 80
> and 40 meter bands will be better than what we are currently experiencing in
> the No. Hemisphere.
> 
> 
> 
> Thanks in advance for any advice you can give me.
> 
> 
> 
> Very 73's,
> 
> 
> 
> Terry, N7TB
> 
> 
> 
> 
> 
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to wun...@wunderwood.org

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com