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KX2

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Andy Clift

KX2

Just received my KX2, but unable to get it to tune an EFHW wire. I’ve tried a home made one and then tried a SOTABEAMS MultiBander that I’ve used successfully with an FT-857. I’ve checked the continuity in the wire and also the continuity in the KX2 between the BNC connector and where the wire connects inside the KX2 (as I removed this to fit the end panels). Battery is at over 11v. Any ideas please?

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Phil Wheeler-2

Re: KX2

Andy,

Is your KX2 receiving or is the problem just with TX?

It sounds like you replaced the end panels with
the 3rd party option. Did you try the KX2 before
doing that?

73, Phil W7OX

On 7/14/16 11:40 AM, Andy Clift wrote:
> Just received my KX2, but unable to get it to tune an EFHW wire. I’ve tried a home made one and then tried a SOTABEAMS MultiBander that I’ve used successfully with an FT-857. I’ve checked the continuity in the wire and also the continuity in the KX2 between the BNC connector and where the wire connects inside the KX2 (as I removed this to fit the end panels). Battery is at over 11v. Any ideas please?

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Don Wilhelm

Re: KX2

In reply to this post by Andy Clift

Andy,

What happens if you connect to a dummy load? Does the KX2 tune it
properly?
If so, then you know the KX2 is operating into a 50 ohm load OK.

Do you have an antenna analyzer? If so, then connect it to the antenna
feedline and look at the impedance - both real and reactive - as well as
the SWR.
That will tell you whether the antenna is troublesome.

You specifically said an EFHW - that should be a resonant antenna. If
instead you have a random length wire (not a halfwave), and what is the
matching device?
Many EFHW antennas need a counterpoise to work - that is why many
manufacturers state a *minimum* length feedline.

If the problem is *not* the antenna, contact Elecraft support.

73,
Don W3FPR

On 7/14/2016 2:40 PM, Andy Clift wrote:

> Just received my KX2, but unable to get it to tune an EFHW wire. I’ve tried a home made one and then tried a SOTABEAMS MultiBander that I’ve used successfully with an FT-857. I’ve checked the continuity in the wire and also the continuity in the KX2 between the BNC connector and where the wire connects inside the KX2 (as I removed this to fit the end panels). Battery is at over 11v. Any ideas please?
>
> ______________________________________________________________
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David Gilbert

Re: KX2

I'm confused why an EFHW should need a counterpoise. If it needs a
counterpoise it isn't actually acting like an EFHW. If it needs a
counterpoise that means there isn't enough choking impedance at the
feedpoint, and it means that the feedline is radiating with the
counterpoise acting as ... well, a counterpoise.

Manufacturers state a minimum length feedline simply to have the
feedline losses help swamp out SWR variations along the line, and of
course to marginally lower the SWR.

Dave
AB7E

On 7/14/2016 1:03 PM, Don Wilhelm wrote:

> Andy,
>
> What happens if you connect to a dummy load? Does the KX2 tune it
> properly?
> If so, then you know the KX2 is operating into a 50 ohm load OK.
>
> Do you have an antenna analyzer? If so, then connect it to the
> antenna feedline and look at the impedance - both real and reactive -
> as well as the SWR.
> That will tell you whether the antenna is troublesome.
>
> You specifically said an EFHW - that should be a resonant antenna. If
> instead you have a random length wire (not a halfwave), and what is
> the matching device?
> Many EFHW antennas need a counterpoise to work - that is why many
> manufacturers state a *minimum* length feedline.
>
> If the problem is *not* the antenna, contact Elecraft support.
>
> 73,
> Don W3FPR
>
> On 7/14/2016 2:40 PM, Andy Clift wrote:
>> Just received my KX2, but unable to get it to tune an EFHW wire. I’ve
>> tried a home made one and then tried a SOTABEAMS MultiBander that
>> I’ve used successfully with an FT-857. I’ve checked the continuity in
>> the wire and also the continuity in the KX2 between the BNC connector
>> and where the wire connects inside the KX2 (as I removed this to fit
>> the end panels). Battery is at over 11v. Any ideas please?
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>
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Don Wilhelm

Re: KX2

Dave,

All that is theoretical does not translate directly to the physical world.
Take a look at http://www.aa5tb.com/efha.html for more information.
The counterpoise does not need to be very long, but it does need to be
present.

If the coupling between the high impedance side of the matching device
is connected at the "ground side" to the shield of the coax, then the
coax shield can act as the counterpoise (with the attendant risk of
RF-in-the-shack), but does require some minimum length of coax to be
effective - the PAR EndFedZ is one example.

73,
Don W3FPR

On 7/14/2016 5:40 PM, David Gilbert wrote:

>
> I'm confused why an EFHW should need a counterpoise. If it needs a
> counterpoise it isn't actually acting like an EFHW. If it needs a
> counterpoise that means there isn't enough choking impedance at the
> feedpoint, and it means that the feedline is radiating with the
> counterpoise acting as ... well, a counterpoise.
>
> Manufacturers state a minimum length feedline simply to have the
> feedline losses help swamp out SWR variations along the line, and of
> course to marginally lower the SWR.
>

David Gilbert

Re: KX2

In reply to this post by David Gilbert

OK, I can buy that ... except that the term "ground reference" as used
by you and Don doesn't really apply. The counterpoise is simply
providing some minimal balance to the high impedance at the end of the
EFHW, and it doesn't need to have anything to do with "ground".

If the counterpoise is located at the rig (as I inadvertently thought
Don was suggesting) instead of at the end of the antenna then indeed the
feedline would radiate, and if located at the rig the impedance
transformation effect of the transmission line (depending upon it's
length) could easily put a low impedance there ... rendering a short
counterpoise essentially ineffective.

For the record, I know how electricity works.

Dave AB7E

On 7/14/2016 3:42 PM, Walter Underwood wrote:

> The transmitter needs to drive into two terminals. That is how electricity works. If you do not provide a ground or a capacitive RF ground (counterpoise), the ground is the chassis of the transmitter. In a big grounded shack, that might be a stable reference. Otherwise, you need to provide a ground reference. Without that, the feed impedance changes every time you touch the rig.
>
> The ground reference does not need to handle much RF current, because of the high impedance feed (around 10 kOhms). Even a little capacitance to ground will stabilize the feedpoint impedance.
>
> A minimum length of coax feedline would reduce the SWR due to losses, but it would also provide an RF ground reference with currents on the outside of the shield. Currents on the inside of the shield are balanced, of course.
>
> Walter Underwood
> [hidden email]
> http://observer.wunderwood.org/ (my blog)
>
>
>> On Jul 14, 2016, at 2:40 PM, David Gilbert <[hidden email]> wrote:
>>
>>
>> I'm confused why an EFHW should need a counterpoise. If it needs a counterpoise it isn't actually acting like an EFHW. If it needs a counterpoise that means there isn't enough choking impedance at the feedpoint, and it means that the feedline is radiating with the counterpoise acting as ... well, a counterpoise.
>>
>> Manufacturers state a minimum length feedline simply to have the feedline losses help swamp out SWR variations along the line, and of course to marginally lower the SWR.
>>
>> Dave
>> AB7E
>>
>>
>> On 7/14/2016 1:03 PM, Don Wilhelm wrote:
>>> Andy,
>>>
>>> What happens if you connect to a dummy load? Does the KX2 tune it properly?
>>> If so, then you know the KX2 is operating into a 50 ohm load OK.
>>>
>>> Do you have an antenna analyzer? If so, then connect it to the antenna feedline and look at the impedance - both real and reactive - as well as the SWR.
>>> That will tell you whether the antenna is troublesome.
>>>
>>> You specifically said an EFHW - that should be a resonant antenna. If instead you have a random length wire (not a halfwave), and what is the matching device?
>>> Many EFHW antennas need a counterpoise to work - that is why many manufacturers state a *minimum* length feedline.
>>>
>>> If the problem is *not* the antenna, contact Elecraft support.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> On 7/14/2016 2:40 PM, Andy Clift wrote:
>>>> Just received my KX2, but unable to get it to tune an EFHW wire. I’ve tried a home made one and then tried a SOTABEAMS MultiBander that I’ve used successfully with an FT-857. I’ve checked the continuity in the wire and also the continuity in the KX2 between the BNC connector and where the wire connects inside the KX2 (as I removed this to fit the end panels). Battery is at over 11v. Any ideas please?
>>>>
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email]
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to [hidden email]
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>> ______________________________________________________________
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>>
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David Gilbert

Re: KX2

In reply to this post by Don Wilhelm

Yup ... that all makes sense. The counterpoise as described by that
link is at the antenna where it should be, and it compensates for the
fact that the network can't produce an infinitely high impedance feed.
I stand corrected.

Using the coax for a "counterpoise" is a really bad idea, though. There
would essentially be no defined counterpoise. There would be no
control at all over what kind of balance the coax provides to the
matching network at the end of the EFHW. Length of the coax would have
an effect, and not just the requirement for some minimum length ... the
transmission line effect of the length would change its characteristics
as seen by the antenna. Proximity of the coax to nearby structures
would also affect what the antenna actually saw.

73,
Dave AB7E

On 7/14/2016 4:56 PM, Don Wilhelm wrote:

> Dave,
>
> All that is theoretical does not translate directly to the physical
> world.
> Take a look at http://www.aa5tb.com/efha.html for more information.
> The counterpoise does not need to be very long, but it does need to be
> present.
>
> If the coupling between the high impedance side of the matching device
> is connected at the "ground side" to the shield of the coax, then the
> coax shield can act as the counterpoise (with the attendant risk of
> RF-in-the-shack), but does require some minimum length of coax to be
> effective - the PAR EndFedZ is one example.
>
> 73,
> Don W3FPR
>
>
> On 7/14/2016 5:40 PM, David Gilbert wrote:
>>
>> I'm confused why an EFHW should need a counterpoise. If it needs a
>> counterpoise it isn't actually acting like an EFHW. If it needs a
>> counterpoise that means there isn't enough choking impedance at the
>> feedpoint, and it means that the feedline is radiating with the
>> counterpoise acting as ... well, a counterpoise.
>>
>> Manufacturers state a minimum length feedline simply to have the
>> feedline losses help swamp out SWR variations along the line, and of
>> course to marginally lower the SWR.
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Don Wilhelm

Re: KX2

Dave,

Most of the commercial end fed halfwave antennas are designed for low
power (100 watts and under). So the use of the coax shield as the
counterpoise element is not a big problem in most cases.

Add to that, the EFHW is an easy solution for portable operation - an
easy up effective antenna.

At the home station where more than QRP power is common, that is where
the difficulties with EFHW antennas become more problematic. In other
words, RF-in-the-shack at QRP levels may not be noticable, but at higher
power levels, it can cause problems.

That being said, I can run my LNR/PAR EndFedZ for 40/20 meters at 100
watts with no apparent problems. I would not want to push it much higher.

73,
Don W3FPR

On 7/14/2016 8:26 PM, David Gilbert wrote:

>
> Yup ... that all makes sense. The counterpoise as described by that
> link is at the antenna where it should be, and it compensates for the
> fact that the network can't produce an infinitely high impedance
> feed. I stand corrected.
>
> Using the coax for a "counterpoise" is a really bad idea, though.
> There would essentially be no defined counterpoise. There would be
> no control at all over what kind of balance the coax provides to the
> matching network at the end of the EFHW. Length of the coax would
> have an effect, and not just the requirement for some minimum length
> ... the transmission line effect of the length would change its
> characteristics as seen by the antenna. Proximity of the coax to
> nearby structures would also affect what the antenna actually saw.
>
> 73,
> Dave AB7E
>
>
>
> On 7/14/2016 4:56 PM, Don Wilhelm wrote:
>> Dave,
>>
>> All that is theoretical does not translate directly to the physical
>> world.
>> Take a look at http://www.aa5tb.com/efha.html for more information.
>> The counterpoise does not need to be very long, but it does need to
>> be present.
>>
>> If the coupling between the high impedance side of the matching
>> device is connected at the "ground side" to the shield of the coax,
>> then the coax shield can act as the counterpoise (with the attendant
>> risk of RF-in-the-shack), but does require some minimum length of
>> coax to be effective - the PAR EndFedZ is one example.
>>
>> 73,
>> Don W3FPR
>>
>>
>> On 7/14/2016 5:40 PM, David Gilbert wrote:
>>>
>>> I'm confused why an EFHW should need a counterpoise. If it needs a
>>> counterpoise it isn't actually acting like an EFHW. If it needs a
>>> counterpoise that means there isn't enough choking impedance at the
>>> feedpoint, and it means that the feedline is radiating with the
>>> counterpoise acting as ... well, a counterpoise.
>>>
>>> Manufacturers state a minimum length feedline simply to have the
>>> feedline losses help swamp out SWR variations along the line, and of
>>> course to marginally lower the SWR.
>>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
>
> ______________________________________________________________
> Elecraft mailing list
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
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>

Don Wilhelm

Re: KX2

In reply to this post by David Gilbert

Keep in mind that the original End Fed Half Wave antenna was the
original Zepp antenna.
A halfwave radiator that was fed from one side of a quarter wave
transmission line.
That antenna was trailed from a Zeppelin airship. The 1/4 wave
transmission line reduced the high impedance of the halfwave antenna to
a low impedance (see transmission line characteristics). The ideal
characteristic impedance for the 1/4 wave transmission line is 300 ohms
- see the work of N3GO - "the J-Pole according to N3GO" at
http://knightlites.org/n3go_workshop/index.htm.

Of course, the transmitters in those airships had adjustable amplifier
tank circuits which could match almost anything except a very high
impedance - that function has been moved to the ATU in recent times and
the PA output stage is designed to work into 50 ohms.

If you want a modern-day example of the EFHW fed with 1/4 wave
transmission line, consider the J-Pole antenna that is popular for VHF -
it is nothing more than the original Zepp antenna oriented vertically.

I have no idea how the "Zepp antenna" designation has been construed in
amateur radio circles to apply to a balanced center fed non-resonant
radiator but it has been so construed that we have to be careful when
saying "I have a Zepp (or Extended Zepp) antenna - it no longer means
what it originally did.

73,
Don W3FPR

On 7/14/2016 8:38 PM, Walter Underwood wrote:

> I totally agree. End-fed half waves are tweaky. One terminal is the antenna wire and the other terminal must be something. The RF will find something to drive as the other “pole” of the antenna. There are no monopole antennas.
>
> It could be the outside of the coax, it could be a “counterpoise” (not fond of that term), or it could be your hand on the key. Ouch.
>
> I was using “ground reference” as the negative side of what you measure RF voltage against. Whatever that is.
>
> There might be an antenna topic with more voodoo than end-fed antennas, but I don’t know what it is. The EC-130J flies a long wire out behind it and broadcasts on medium wave. I guess the other pole of that antenna is the airplane itself. http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104535/ec-130j-commando-solo.aspx <http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104535/ec-130j-commando-solo.aspx>
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>
>> On Jul 14, 2016, at 5:14 PM, David Gilbert <[hidden email]> wrote:
>>
>> OK, I can buy that ... except that the term "ground reference" as used by you and Don doesn't really apply. The counterpoise is simply providing some minimal balance to the high impedance at the end of the EFHW, and it doesn't need to have anything to do with "ground".
>>
>> If the counterpoise is located at the rig (as I inadvertently thought Don was suggesting) instead of at the end of the antenna then indeed the feedline would radiate, and if located at the rig the impedance transformation effect of the transmission line (depending upon it's length) could easily put a low impedance there ... rendering a short counterpoise essentially ineffective.
>>
>> For the record, I know how electricity works.
>>
>> Dave AB7E
>>
>>
>> On 7/14/2016 3:42 PM, Walter Underwood wrote:
>>> The transmitter needs to drive into two terminals. That is how electricity works. If you do not provide a ground or a capacitive RF ground (counterpoise), the ground is the chassis of the transmitter. In a big grounded shack, that might be a stable reference. Otherwise, you need to provide a ground reference. Without that, the feed impedance changes every time you touch the rig.
>>>
>>> The ground reference does not need to handle much RF current, because of the high impedance feed (around 10 kOhms). Even a little capacitance to ground will stabilize the feedpoint impedance.
>>>
>>> A minimum length of coax feedline would reduce the SWR due to losses, but it would also provide an RF ground reference with currents on the outside of the shield. Currents on the inside of the shield are balanced, of course.
>>>
>>> Walter Underwood
>>> [hidden email]
>>> http://observer.wunderwood.org/ (my blog)
>>>
>>>
>>>> On Jul 14, 2016, at 2:40 PM, David Gilbert <[hidden email]> wrote:
>>>>
>>>>
>>>> I'm confused why an EFHW should need a counterpoise. If it needs a counterpoise it isn't actually acting like an EFHW. If it needs a counterpoise that means there isn't enough choking impedance at the feedpoint, and it means that the feedline is radiating with the counterpoise acting as ... well, a counterpoise.
>>>>
>>>> Manufacturers state a minimum length feedline simply to have the feedline losses help swamp out SWR variations along the line, and of course to marginally lower the SWR.
>>>>
>>>> Dave
>>>> AB7E
>>>>
>>>>
>>>> On 7/14/2016 1:03 PM, Don Wilhelm wrote:
>>>>> Andy,
>>>>>
>>>>> What happens if you connect to a dummy load? Does the KX2 tune it properly?
>>>>> If so, then you know the KX2 is operating into a 50 ohm load OK.
>>>>>
>>>>> Do you have an antenna analyzer? If so, then connect it to the antenna feedline and look at the impedance - both real and reactive - as well as the SWR.
>>>>> That will tell you whether the antenna is troublesome.
>>>>>
>>>>> You specifically said an EFHW - that should be a resonant antenna. If instead you have a random length wire (not a halfwave), and what is the matching device?
>>>>> Many EFHW antennas need a counterpoise to work - that is why many manufacturers state a *minimum* length feedline.
>>>>>
>>>>> If the problem is *not* the antenna, contact Elecraft support.
>>>>>
>>>>> 73,
>>>>> Don W3FPR
>>>>>
>>>>> On 7/14/2016 2:40 PM, Andy Clift wrote:
>>>>>> Just received my KX2, but unable to get it to tune an EFHW wire. I’ve tried a home made one and then tried a SOTABEAMS MultiBander that I’ve used successfully with an FT-857. I’ve checked the continuity in the wire and also the continuity in the KX2 between the BNC connector and where the wire connects inside the KX2 (as I removed this to fit the end panels). Battery is at over 11v. Any ideas please?
>>>>>>
>>>>>> ______________________________________________________________
>>>>>> Elecraft mailing list
>>>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>>>> Post: mailto:[hidden email]
>>>>>>
>>>>>> This list hosted by: http://www.qsl.net
>>>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>>>> Message delivered to [hidden email]
>>>>> ______________________________________________________________
>>>>> Elecraft mailing list
>>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>>> Post: mailto:[hidden email]
>>>>>
>>>>> This list hosted by: http://www.qsl.net
>>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>>> Message delivered to [hidden email]
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email]
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to [hidden email]
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
> ______________________________________________________________
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NS0R

Re: KX2

A few years ago I built a parallel LC network from a roller inductor and a variable cap rated for approximately 2.5kv and have used it to match 20 meter EFHW many times. I run 500 watts into it from the kpa500 through a choke balun in the shack. I use (5) 8 foot radials for a counterpoise and I tape the wire to a 40 foot spiderbeam fiberglass pole in a vertical configuration. I have never had any problems with rf in the shack using this antenna with the choke. In fact I have more problems with rf from my 80 meter inverted-L than I do the EFHW. I built the antenna for field day use but I have had excellent results with it in several local and DX contests. I easily have over 3000 q's with this antenna and the only real complaint I have is that at times it can be a bit noisy. I originally built the box to match a 40 meter halfsquare but it works well on 20, 80, and 160 as well.

Sent from my iPhone

> On Jul 14, 2016, at 8:01 PM, Don Wilhelm <[hidden email]> wrote:
>
> Keep in mind that the original End Fed Half Wave antenna was the original Zepp antenna.
> A halfwave radiator that was fed from one side of a quarter wave transmission line.
> That antenna was trailed from a Zeppelin airship. The 1/4 wave transmission line reduced the high impedance of the halfwave antenna to a low impedance (see transmission line characteristics). The ideal characteristic impedance for the 1/4 wave transmission line is 300 ohms - see the work of N3GO - "the J-Pole according to N3GO" at http://knightlites.org/n3go_workshop/index.htm.
>
> Of course, the transmitters in those airships had adjustable amplifier tank circuits which could match almost anything except a very high impedance - that function has been moved to the ATU in recent times and the PA output stage is designed to work into 50 ohms.
>
> If you want a modern-day example of the EFHW fed with 1/4 wave transmission line, consider the J-Pole antenna that is popular for VHF - it is nothing more than the original Zepp antenna oriented vertically.
>
> I have no idea how the "Zepp antenna" designation has been construed in amateur radio circles to apply to a balanced center fed non-resonant radiator but it has been so construed that we have to be careful when saying "I have a Zepp (or Extended Zepp) antenna - it no longer means what it originally did.
>
> 73,
> Don W3FPR
>
>> On 7/14/2016 8:38 PM, Walter Underwood wrote:
>> I totally agree. End-fed half waves are tweaky. One terminal is the antenna wire and the other terminal must be something. The RF will find something to drive as the other “pole” of the antenna. There are no monopole antennas.
>>
>> It could be the outside of the coax, it could be a “counterpoise” (not fond of that term), or it could be your hand on the key. Ouch.
>>
>> I was using “ground reference” as the negative side of what you measure RF voltage against. Whatever that is.
>>
>> There might be an antenna topic with more voodoo than end-fed antennas, but I don’t know what it is. The EC-130J flies a long wire out behind it and broadcasts on medium wave. I guess the other pole of that antenna is the airplane itself. http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104535/ec-130j-commando-solo.aspx <http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104535/ec-130j-commando-solo.aspx>
>>
>> wunder
>> K6WRU
>> Walter Underwood
>> CM87wj
>> http://observer.wunderwood.org/ (my blog)
>>
>>> On Jul 14, 2016, at 5:14 PM, David Gilbert <[hidden email]> wrote:
>>>
>>> OK, I can buy that ... except that the term "ground reference" as used by you and Don doesn't really apply. The counterpoise is simply providing some minimal balance to the high impedance at the end of the EFHW, and it doesn't need to have anything to do with "ground".
>>>
>>> If the counterpoise is located at the rig (as I inadvertently thought Don was suggesting) instead of at the end of the antenna then indeed the feedline would radiate, and if located at the rig the impedance transformation effect of the transmission line (depending upon it's length) could easily put a low impedance there ... rendering a short counterpoise essentially ineffective.
>>>
>>> For the record, I know how electricity works.
>>>
>>> Dave AB7E
>>>
>>>
>>>> On 7/14/2016 3:42 PM, Walter Underwood wrote:
>>>> The transmitter needs to drive into two terminals. That is how electricity works. If you do not provide a ground or a capacitive RF ground (counterpoise), the ground is the chassis of the transmitter. In a big grounded shack, that might be a stable reference. Otherwise, you need to provide a ground reference. Without that, the feed impedance changes every time you touch the rig.
>>>>
>>>> The ground reference does not need to handle much RF current, because of the high impedance feed (around 10 kOhms). Even a little capacitance to ground will stabilize the feedpoint impedance.
>>>>
>>>> A minimum length of coax feedline would reduce the SWR due to losses, but it would also provide an RF ground reference with currents on the outside of the shield. Currents on the inside of the shield are balanced, of course.
>>>>
>>>> Walter Underwood
>>>> [hidden email]
>>>> http://observer.wunderwood.org/ (my blog)
>>>>
>>>>
>>>>> On Jul 14, 2016, at 2:40 PM, David Gilbert <[hidden email]> wrote:
>>>>>
>>>>>
>>>>> I'm confused why an EFHW should need a counterpoise. If it needs a counterpoise it isn't actually acting like an EFHW. If it needs a counterpoise that means there isn't enough choking impedance at the feedpoint, and it means that the feedline is radiating with the counterpoise acting as ... well, a counterpoise.
>>>>>
>>>>> Manufacturers state a minimum length feedline simply to have the feedline losses help swamp out SWR variations along the line, and of course to marginally lower the SWR.
>>>>>
>>>>> Dave
>>>>> AB7E
>>>>>
>>>>>
>>>>>> On 7/14/2016 1:03 PM, Don Wilhelm wrote:
>>>>>> Andy,
>>>>>>
>>>>>> What happens if you connect to a dummy load? Does the KX2 tune it properly?
>>>>>> If so, then you know the KX2 is operating into a 50 ohm load OK.
>>>>>>
>>>>>> Do you have an antenna analyzer? If so, then connect it to the antenna feedline and look at the impedance - both real and reactive - as well as the SWR.
>>>>>> That will tell you whether the antenna is troublesome.
>>>>>>
>>>>>> You specifically said an EFHW - that should be a resonant antenna. If instead you have a random length wire (not a halfwave), and what is the matching device?
>>>>>> Many EFHW antennas need a counterpoise to work - that is why many manufacturers state a *minimum* length feedline.
>>>>>>
>>>>>> If the problem is *not* the antenna, contact Elecraft support.
>>>>>>
>>>>>> 73,
>>>>>> Don W3FPR
>>>>>>
>>>>>>> On 7/14/2016 2:40 PM, Andy Clift wrote:
>>>>>>> Just received my KX2, but unable to get it to tune an EFHW wire. I’ve tried a home made one and then tried a SOTABEAMS MultiBander that I’ve used successfully with an FT-857. I’ve checked the continuity in the wire and also the continuity in the KX2 between the BNC connector and where the wire connects inside the KX2 (as I removed this to fit the end panels). Battery is at over 11v. Any ideas please?
>>>>>>>
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Phil Wheeler-2

Re: KX2

But Morgan, how many KX2s will fit inside your
roller inductor? Seems a bit of an overkill for
QRP ops :-)

73, Phil W7OX

On 7/14/16 8:34 PM, Morgan Bailey wrote:
> A few years ago I built a parallel LC network from a roller inductor and a variable cap rated for approximately 2.5kv and have used it to match 20 meter EFHW many times. I run 500 watts into it from the kpa500 through a choke balun in the shack. I use (5) 8 foot radials for a counterpoise and I tape the wire to a 40 foot spiderbeam fiberglass pole in a vertical configuration. I have never had any problems with rf in the shack using this antenna with the choke. In fact I have more problems with rf from my 80 meter inverted-L than I do the EFHW. I built the antenna for field day use but I have had excellent results with it in several local and DX contests. I easily have over 3000 q's with this antenna and the only real complaint I have is that at times it can be a bit noisy. I originally built the box to match a 40 meter halfsquare but it works well on 20, 80, and 160 as well.
>
> Sent from my iPhone

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Edward R Cole

Re: KX2

In reply to this post by Andy Clift

Don's comments on the fact that a J-pole is merely a Zepp where the
1/2 wave radiator is vertical is something I discovered a few years
ago. I have a dual-band J-pole on 10m/6m which works well.

Note that the bottom end of the 1/4 wave matching stub is
shorted. By attaching coax to the stub one can find 50-ohm match
just by sliding up from the ground end. It was about six inches for
the 10m J-pole.

I do not have my construction page back on my website as yet. I used
aluminum tubing about 25-foot long for the 10m version. You might
want to use a common-mode choke at the coax feed to prevent coax radiation.

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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Guy Olinger K2AV

Re: KX2

In reply to this post by David Gilbert

We need to distinguish between an end fed wire (EFW) and an end fed
HALF WAVE wire (EFHW). If one has an actual half wave wire being
called by the name EFHW, several things are true. One, the feed Z at
the end is ridiculously high, with HV and painful burns in play even
for 100W. Many (most?) antenna tuners do NOT handle Z that high, while
most tuners DO handle 600 ohm Z from an EFW well, particularly with
common 4:1 reduction devices.

One of the advantages of an EFHW fed at the ground, is that voltage
being very high means that current is very low, and even otherwise
pathetic grounds are efficient. You CAN feed an EFHW against a ground
rod. In a portable situation something like one of those six inch
galvanized nails driven mostly into the ground and soaked with a
little water, will settle the counterpoise issue nicely.

On 80 meters an end fed half wave L (EFHWL) fed against ground is
probably the best all around performing single wire 80m antenna
available. It's lack of popularity is due to not being able to
successfully feed it directly from coax and lack of tuner boxes off
the shelf Needs a matching network at the feedpoint, and at QRO, has
to deal with very high RF voltages. It has dual polarization, working
for both DX and local, with no holes in the pattern, and the current
maximum is up around the bend in the L, reducing vertical polarization
loss to both ground and nearby clutter.

On the other hand an end fed wire (EFW) that stays well away from even
quarter wave multiples on bands in use, particularly with a 4:1
reduction device, will tune easily. The disadvantage with EFW is that
pathetic ground no longer functions well as a counterpoise. The tuner
needs to isolate ground and the case from the antenna side tuner
connections, one of which needs to be a planned counterpoise, and the
isolation needs to be efficient (not lossy) with high reactance on the
antenna side.

You can get RF through lesser arrangements and make contacts, but you
are paying for the "lesser" with loss.

I agree that EFHW's are "tweaky". IMHO more than made up for by
performance. EFHW "tweaky" *can* be tamed to considerable degree, but
that's another subject.

73, Guy K2AV

On Thu, Jul 14, 2016 at 8:26 PM, David Gilbert <[hidden email]> wrote:

> Yup ... that all makes sense. The counterpoise as described by that link is
> at the antenna where it should be, and it compensates for the fact that the
> network can't produce an infinitely high impedance feed. I stand corrected.
>
> Using the coax for a "counterpoise" is a really bad idea, though. There
> would essentially be no defined counterpoise. There would be no control at
> all over what kind of balance the coax provides to the matching network at
> the end of the EFHW. Length of the coax would have an effect, and not just
> the requirement for some minimum length ... the transmission line effect of
> the length would change its characteristics as seen by the antenna.
> Proximity of the coax to nearby structures would also affect what the
> antenna actually saw.
>
> 73,
> Dave AB7E

Robert Cunnings

Re: KX2

In reply to this post by Don Wilhelm

Here's another aricle, by W8JI, on feeding the EFHW:

http://www.w8ji.com/end-fed_1_2_wave_matching_system_end%20feed.htm

Bob NW8L

On Thu, 14 Jul 2016, Don Wilhelm wrote:

> Dave,
>
> All that is theoretical does not translate directly to the physical world.
> Take a look at http://www.aa5tb.com/efha.html for more information.
> The counterpoise does not need to be very long, but it does need to be
> present.
>
> If the coupling between the high impedance side of the matching device is
> connected at the "ground side" to the shield of the coax, then the coax
> shield can act as the counterpoise (with the attendant risk of
> RF-in-the-shack), but does require some minimum length of coax to be
> effective - the PAR EndFedZ is one example.
>
> 73,
> Don W3FPR
>

Jim GM

Re: KX2

In reply to this post by Andy Clift

Soun ds like a menu setting is in the wrong setting.

Jim K9TF

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Rick Robinson

KX2

In reply to this post by Robert Cunnings

I don't want to come off as a "A-Hole" but the use of efhw for any end fed
antenna is really getting out of hand. We as hams need to step up our game
in regards to our communication skills of day to day speech. We, as
hams,are regarded as communication specialists and this should go with our
speech as well as our knowledge. A efhw is a single band, narrow frequency,
antenna. It is a half wave of one frequency with regards to the length of
the antenna with some minor adjustments for its mounting. An end fed
antenna is just that, a random length of wire fed at one end of the wire. I
know this may seem to some as being petty but it degrades the knowledge we
have learned as amateurs. If this persists the ones joining the hobby may
think that this is an accurate description and then spread this to others,
as it seems it already has, and dumb down our status within part 97.1 (d)
Expansion of the existing reservoir within the amateur radio service of
trained operators, technicians, and electronics experts. My 2 cents.

--
Rick, W8ZT

Sent from Gmail Mobile
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k6dgw

Re: KX2

In reply to this post by Andy Clift

OK, my "80-10 EFHW", which is how it's marketed, is really an "EFHWO8OBWGOOBT"? (End Fed On 80 But Works Great On Other Bands Too). :-)

73,

Fred K6DGW
TDY in SoCal on my Kindle

Rick Robinson <[hidden email]> wrote:

>I don't want to come off as a "A-Hole" but the use of efhw for any end fed
>antenna is really getting out of hand. We as hams need to step up our game
>in regards to our communication skills of day to day speech. We, as
>hams,are regarded as communication specialists and this should go with our
>speech as well as our knowledge. A efhw is a single band, narrow frequency,
>antenna. It is a half wave of one frequency with regards to the length of
>the antenna with some minor adjustments for its mounting. An end fed
>antenna is just that, a random length of wire fed at one end of the wire. I
>know this may seem to some as being petty but it degrades the knowledge we
>have learned as amateurs. If this persists the ones joining the hobby may
>think that this is an accurate description and then spread this to others,
>as it seems it already has, and dumb down our status within part 97.1 (d)
>Expansion of the existing reservoir within the amateur radio service of
>trained operators, technicians, and electronics experts. My 2 cents.
>
>--
>Rick, W8ZT
>
>Sent from Gmail Mobile
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Jim GM

Re: KX2

In reply to this post by Andy Clift

Hmmmm Could it be a Long wire, Inverted L or even a comes under so many of the Slopper perhaps?

Jim K9TF

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Guy Olinger K2AV

Re: KX2

In reply to this post by k6dgw

On Fri, Jul 15, 2016 at 12:24 PM, Fred C. Jensen <[hidden email]> wrote:
> (End Fed On 80 But Works Great On Other Bands Too). :-)

One of the endearing qualities of an 80 meter end-fed half-wave L is
that it is usually a very good antenna for both 7 and 10 MHz. If the
bend of the L is somewhere close to the middle of the wire, as in up
55 out 75, up 70 out 60, we get some interesting if counter-intuitive
effects.

On 40 the wire acts like a 40 dipole hung in the same air space. Due
to the interaction of the vertical and horizontal parts of the L, the
vertical wire becomes a single wire feedline. Very easy to model. Try
it and get used to the idea that to the naked brain that doesn't make
any sense.

On 30m the pattern is a low-ish angle omnidirectional.

Since it is a high Z feedpoint on all three bands, one half-wave on
80, two on 40 and three on 30, the use of pathetic ground is permitted
at the feedpoint. If you add the switching and an FCP, this becomes a
very efficient antenna for 160-80-40-30. Use of the pathetic ground on
160, since that is a *current* feed rather than a voltage feed will
produce a pathetic 160 radiated signal.

73, Guy K2AV
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