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KPA1500 RFI on 12m

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K8TE

Re: KPA1500 RFI on 12m

Most hams cut their antenna length for lowest VSWR which is often NOT the
resonant point. Resonance occurs when XsubL equals XsubC. That means there
is no reactance at one frequency. Impedance varies greatly with height
above ground. The greatest radiation occurs at resonance which, again, is
often not at the lowest VSWR. This is why a good antenna analyzer that
displays both VSWR and reactance is so helpful.

Web sites abound with advice to cut the antenna for lowest VSWR. Like
politics, the truth is difficult to find and, apparently, often hard to
believe. And, anecdotal statements about how an antenna works
(WORK--WithOut Real Knowledge--K0BG) often has little to do with its
comparative performance. Too few of us use real data (like WSPRLite) to
compare antennas and arrive at conclusions based on comparative data.

I liked the Pacificon theme this year: "The Science of Radio" That didn't
always apply in some of the presentations, but fortunately did in most I
attended.

73, Bill, K8TE

--
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Phil Kane-2

Re: RX noise and 2-wire lines (was: KPA1500 RFI on 12m)

In reply to this post by Lyn WØLEN

On 10/27/2019 11:33 AM, Lyn Norstad wrote:

> Your mileage may vary, but for anyone looking to try something new
> (actually a very OLD design), it's a fun project.

If I had 400 feet for an antenna that's the type of antenna that I would
go for too, but I barely have 400 inches. Have fun with the antenna.

73 de K2ASP - Phil Kane
Elecraft K2/100 s/n 5402

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon
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Grant Youngman-2

Re: RX noise and 2-wire lines (was: KPA1500 RFI on 12m)

Don’t you love it when guy’s are taking about their latest large antenna projects? I read these things, look wistfully out back into my 30’x30’ townhouse courtyard, and wonder if I can dare put my Buddipole 40M dipole up one more foot without attracting the ire of some resident who will report my illicit activity to the HOA. That’s about as big as my antenna projects can get 🤣🤣

Grant NQ5T

>
>
> On 10/27/2019 11:33 AM, Lyn Norstad wrote:
>
>> Your mileage may vary, but for anyone looking to try something new
>> (actually a very OLD design), it's a fun project.
>
> If I had 400 feet for an antenna that's the type of antenna that I would
> go for too, but I barely have 400 inches. Have fun with the antenna.

> 73 de K2ASP - Phil Kane
> Elecraft K2/100 s/n 5402
>

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Lyn WØLEN

Re: RX noise and 2-wire lines (was: KPA1500 RFI on 12m)

Who ... me? It seems like foreign territory to fall into that category after spending most of my 50 ham years on the other end of the stick.

When I retired a couple years ago, and decided to get serious about ham radio again, I managed to successfully run for a seat on our HOA Board (it's easy ... nobody wants the job). Eventually I was able to get our very strict guidelines changed to allow "reasonable" outside antennas for licensed amateurs. And so far, no complaints on my setup.

Most recently, I have agreed to serve as the Architectural and Landscape Review "committee" so if there is a complaint ... well ... you get the picture.

73
Lyn, WØLEN

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Grant Youngman
Sent: Monday, October 28, 2019 1:54 PM
To: [hidden email]
Cc: Elecraft Refl
Subject: Re: [Elecraft] RX noise and 2-wire lines (was: KPA1500 RFI on 12m)

Don’t you love it when guy’s are taking about their latest large antenna projects? I read these things, look wistfully out back into my 30’x30’ townhouse courtyard, and wonder if I can dare put my Buddipole 40M dipole up one more foot without attracting the ire of some resident who will report my illicit activity to the HOA. That’s about as big as my antenna projects can get 🤣🤣

Grant NQ5T

>
>
> On 10/27/2019 11:33 AM, Lyn Norstad wrote:
>
>> Your mileage may vary, but for anyone looking to try something new
>> (actually a very OLD design), it's a fun project.
>
> If I had 400 feet for an antenna that's the type of antenna that I would
> go for too, but I barely have 400 inches. Have fun with the antenna.

> 73 de K2ASP - Phil Kane
> Elecraft K2/100 s/n 5402
>

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Rick WA6NHC-2

Re: RX noise and 2-wire lines

In reply to this post by Grant Youngman-2

I had a similar 370' antenna hidden on the oaks above 'the common area'
(that no one ever used, it wasn't developed); it allowed me 200+
countries. That HOA had a severe case of cranial rectumitus, folks with
an inflated sense of self importance and the false sense of power. I'll
be durned if I need someone's permission to plant a flower on MY land
and their choice of paint color was akin to what is seen inside a
newborn's diaper.

I escaped the state and haven't missed it for a moment. With all the
current events, I'm extra glad to not be an unwilling participant there;
it's approaching third world status quickly.

Now, I'm almost done assembling a SteppIR DB36 (80-6M, it, the tower and
prop pitch were parts of an estate sale) where the noise floor is
honestly 28-30dB lower. The only remaining issue now is time before the
snow accumulates making it too difficult to finish (another 10 hours
ought to do it, but snowing now). The nearest neighbor (also a ham,
with a SteppIR) is 700' away; we each have room to breathe and will
coordinate operations should the need arise (he contests, I avoid them;
shouldn't be any issues, besides he is QRP and I have the KPA1500).

Not everyone can do this, I get it. (I even sold at a large loss.) But
if such a move is within your reach, do it. Life is too short to have
to put up with corporate stupidity and huge false egos and (often
hidden) agendas. And then there is the politics, ugh. The cost of
living here is less and the quality of life is VASTLY improved, even if
I have to drive 75 miles for the closest Costco.

When I arrived here I was told "Welcome to America!" and that has been
true, absolutely spot on, every day. I am truly blessed.

73,
Rick NHC
N Idaho (we're closed, please try South Dakota?)

On 10/28/2019 11:54 AM, Grant Youngman wrote:
> Don’t you love it when guy’s are taking about their latest large antenna projects? I read these things, look wistfully out back into my 30’x30’ townhouse courtyard, and wonder if I can dare put my Buddipole 40M dipole up one more foot without attracting the ire of some resident who will report my illicit activity to the HOA. That’s about as big as my antenna projects can get 🤣🤣
>
> Grant NQ5T
>
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Gwen Patton

Re: RX noise and 2-wire lines

When I lived in a 3rd floor apartment, I used to use a slingshot to fire a
fishing sinker with a 28-gauge magnet wire attached, across the parking lot
under our balcony into a wooded area's trees. Then I dangled a counterpoise
behind a downspout where it wouldn't be seen, and tuned it all with a
random wire tuner. Got me to Europe fairly consistently, and lots of the
US. Nobody ever saw it. I even had a 2m Moxon inside a wooden garden
privacy screen on my balcony that kept the radiation outside the building
so it no longer got into the downstairs neighbor's clock radio.

73,
Gwen, NG3P

On Mon, Oct 28, 2019 at 4:40 PM Rick WA6NHC <[hidden email]> wrote:

> I had a similar 370' antenna hidden on the oaks above 'the common area'
> (that no one ever used, it wasn't developed); it allowed me 200+
> countries. That HOA had a severe case of cranial rectumitus, folks with
> an inflated sense of self importance and the false sense of power. I'll
> be durned if I need someone's permission to plant a flower on MY land
> and their choice of paint color was akin to what is seen inside a
> newborn's diaper.
>
> I escaped the state and haven't missed it for a moment. With all the
> current events, I'm extra glad to not be an unwilling participant there;
> it's approaching third world status quickly.
>
> Now, I'm almost done assembling a SteppIR DB36 (80-6M, it, the tower and
> prop pitch were parts of an estate sale) where the noise floor is
> honestly 28-30dB lower. The only remaining issue now is time before the
> snow accumulates making it too difficult to finish (another 10 hours
> ought to do it, but snowing now). The nearest neighbor (also a ham,
> with a SteppIR) is 700' away; we each have room to breathe and will
> coordinate operations should the need arise (he contests, I avoid them;
> shouldn't be any issues, besides he is QRP and I have the KPA1500).
>
> Not everyone can do this, I get it. (I even sold at a large loss.) But
> if such a move is within your reach, do it. Life is too short to have
> to put up with corporate stupidity and huge false egos and (often
> hidden) agendas. And then there is the politics, ugh. The cost of
> living here is less and the quality of life is VASTLY improved, even if
> I have to drive 75 miles for the closest Costco.
>
> When I arrived here I was told "Welcome to America!" and that has been
> true, absolutely spot on, every day. I am truly blessed.
>
> 73,
> Rick NHC
> N Idaho (we're closed, please try South Dakota?)
>
> On 10/28/2019 11:54 AM, Grant Youngman wrote:
> > Don’t you love it when guy’s are taking about their latest large antenna
> projects? I read these things, look wistfully out back into my 30’x30’
> townhouse courtyard, and wonder if I can dare put my Buddipole 40M dipole
> up one more foot without attracting the ire of some resident who will
> report my illicit activity to the HOA. That’s about as big as my antenna
> projects can get 🤣🤣
> >
> > Grant NQ5T
> >
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

--

-+-+-+-+-
Jenny Everywhere's Infinite: Quark Time
http://quarktime.net
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Drew AF2Z

Re: RX noise and 2-wire lines

In reply to this post by Vic Rosenthal

My RX antenna is a pair of small amplified stacked loops. It uses the
LZ1AQ amplifier board fed with common FTP (foil twisted pair) cable,
which provides the supply voltage, control lines and a shielded twisted
pair for the signal. I don't think you can get any better noise
isolation than that.

It is a lot quieter than my transmitting antennas; lower signal levels
as well, but often a better signal-to-noise ratio than the transmit
antennas.

73,
Drew
AF2Z

On 10/26/19 10:11, Victor Rosenthal 4X6GP wrote:

> Jim,
>
> I have to disagree about balanced line. Unlike coax, both conductors are
> exposed to external RF fields, so common mode noise will be rejected. If
> the antenna and line are properly balanced (not always easy to do, I
> admit) and if it is fed through a balanced antenna tuner, there is no
> reason for it to be noisier than coax. Yes, it can't be choked, but it
> doesn't need to be.
>
> My antenna is a 10m long rotary dipole fed with open line. It has gone
> through several iterations and I've been very careful to install the
> line so that it is perpendicular to the antenna for as far as possible,
> etc. I've tried various balun arrangements, but the system that works
> best, both for reducing RF in the shack when transmitting and noise
> immunity when receiving, is a Johnson kW Matchbox.
>
> There is a building taller than mine a few hundred meters away from it,
> and a very distinct noise peak when the antenna is turned toward it,
> which seems to indicate that the noise is picked up by the antenna, not
> the line. I notice the same noise peak with a coax-fed shielded loop
> antenna, so it is definitely coming from the building, and isn't an
> artifact of the alignment of the antenna to the line. I am pretty sure
> I have at least a 10 dB difference in noise when a band is open (at
> least, when the antenna is not aimed at that building), but I will wait
> until the band is solidly dead tonight to check that out.
>
> My pattern is a form of figure 8 on 40-10 meters, but you are right that
> you can't maintain the pattern over a greater frequency range.
>
> My main point is that there is nothing inherently noisy about a two-wire
> transmission line!
>
> 73,
> Victor, 4X6GP
> Rehovot, Israel
> Formerly K2VCO
> CWops no. 5
> http://www.qsl.net/k2vco/
> On 26-Oct-2019 10:32, Jim Brown wrote:
>> On 10/25/2019 2:01 PM, Bob McGraw K4TAX wrote:
>>> Except for my 6M yagi, all of my antennas are non-resonant antennas.
>>> My favorite is the 256 ft center fed wire {resonant at 1.825 MHz}
>>> with a balanced feed.
>>
>> Dean Straw, N6BV, retired editor of the ARRL Antenna Book and Antenna
>> Compendiums, is a very smart engineer and a very good friend. But his
>> promotion of this sort of antenna is probably the greatest error of
>> his time in that job, an idea whose time is LONG past, for many
>> reasons. Primary -- 1) it cannot be choked to kill noise on RX, and
>> 99.9% of hams live surrounded by local noise and 2) it's pattern is
>> different on every frequency.
>>
>> I am a strong believer in resonant antennas for each band, if if the
>> must be multi-band antennas like fan dipoles to fit in the available
>> space. For example, a 20/15/10 fan fits in 33 ft and works great, with
>> a predictable pattern on each band. An 80/40 fan works on 15M, with a
>> predictable pattern on both 80 and 40. Hypower Antenna company sells
>> loaded antennas that are resonant on 80 and 40 and fit into about 100
>> ft; I used one in Chicago on 30 to great effect. All of these antennas
>> are fed with 50 or 75 ohm coax, and CAN be choked to kill RX noise.
>>
>> RX noise is a VERY big deal -- if you can't hear 'em, you can't work
>> 'em. If you haven't worked to minimize your RX noise, you're DXing
>> with one hand tied behind your back! My friend AG6EE goes to remote
>> locations in NV, OR, and CA to light up rare grids with 1kW on 6M.
>> Folks trying to work him complain of one-way propagation because he
>> hears them really well and the don't hear him, but the REAL problem is
>> their local RX noise.
>>
>> http://k9yc.com/KillingReceiveNoise.pdf Text, NCJ article
>> http://k9yc.com/KillingRXNoiseVisalia.pdf Slides Visalia talk
>>
>> 73, Jim K9YC
>
> ______________________________________________________________
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>
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David Christ

Re: RX noise and 2-wire lines (was: KPA1500 RFI on 12m)

In reply to this post by Lyn WØLEN

Sometimes it happens, I got permission for a 30 foot tower and a K4KIO beam. When asking permission I emphasized the emergency and public service angle and showed I had a one million dollar umbrella policy. Those are dirt cheap.

Had a picture of a similar installation which kept the scary imaginations under control.

David K0LUM

> On Oct 28, 2019, at 2:45 PM, Lyn Norstad <[hidden email]> wrote:
>
> Who ... me? It seems like foreign territory to fall into that category after spending most of my 50 ham years on the other end of the stick.
>
> When I retired a couple years ago, and decided to get serious about ham radio again, I managed to successfully run for a seat on our HOA Board (it's easy ... nobody wants the job). Eventually I was able to get our very strict guidelines changed to allow "reasonable" outside antennas for licensed amateurs. And so far, no complaints on my setup.
>
> Most recently, I have agreed to serve as the Architectural and Landscape Review "committee" so if there is a complaint ... well ... you get the picture.
>
> 73
> Lyn, WØLEN
>
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On Behalf Of Grant Youngman
> Sent: Monday, October 28, 2019 1:54 PM
> To: [hidden email]
> Cc: Elecraft Refl
> Subject: Re: [Elecraft] RX noise and 2-wire lines (was: KPA1500 RFI on 12m)
>
> Don’t you love it when guy’s are taking about their latest large antenna projects? I read these things, look wistfully out back into my 30’x30’ townhouse courtyard, and wonder if I can dare put my Buddipole 40M dipole up one more foot without attracting the ire of some resident who will report my illicit activity to the HOA. That’s about as big as my antenna projects can get 🤣🤣
>
> Grant NQ5T
>
>>
>>
>> On 10/27/2019 11:33 AM, Lyn Norstad wrote:
>>
>>> Your mileage may vary, but for anyone looking to try something new
>>> (actually a very OLD design), it's a fun project.
>>
>> If I had 400 feet for an antenna that's the type of antenna that I would
>> go for too, but I barely have 400 inches. Have fun with the antenna.
>
>> 73 de K2ASP - Phil Kane
>> Elecraft K2/100 s/n 5402
>>
>
> ______________________________________________________________
> 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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Elecraft mailing list

Re: RX noise and 2-wire lines

In reply to this post by Drew AF2Z

I would like to know more about your receive antenna. At my home, I deal with S7-S9+ noise and am looking for some way to be able to operate besides FT8.

Thanks…

David Thompson, AG7TX
Jack of All Trades
Master of None
[hidden email]

> On Oct 28, 2019, at 14:31, Drew AF2Z <[hidden email]> wrote:
>
> My RX antenna is a pair of small amplified stacked loops. It uses the LZ1AQ amplifier board fed with common FTP (foil twisted pair) cable, which provides the supply voltage, control lines and a shielded twisted pair for the signal. I don't think you can get any better noise isolation than that.
>
> It is a lot quieter than my transmitting antennas; lower signal levels as well, but often a better signal-to-noise ratio than the transmit antennas.
>
> 73,
> Drew
> AF2Z
>
>
> On 10/26/19 10:11, Victor Rosenthal 4X6GP wrote:
>> Jim,
>> I have to disagree about balanced line. Unlike coax, both conductors are exposed to external RF fields, so common mode noise will be rejected. If the antenna and line are properly balanced (not always easy to do, I admit) and if it is fed through a balanced antenna tuner, there is no reason for it to be noisier than coax. Yes, it can't be choked, but it doesn't need to be.
>> My antenna is a 10m long rotary dipole fed with open line. It has gone through several iterations and I've been very careful to install the line so that it is perpendicular to the antenna for as far as possible, etc. I've tried various balun arrangements, but the system that works best, both for reducing RF in the shack when transmitting and noise immunity when receiving, is a Johnson kW Matchbox.
>> There is a building taller than mine a few hundred meters away from it, and a very distinct noise peak when the antenna is turned toward it, which seems to indicate that the noise is picked up by the antenna, not the line. I notice the same noise peak with a coax-fed shielded loop antenna, so it is definitely coming from the building, and isn't an artifact of the alignment of the antenna to the line. I am pretty sure I have at least a 10 dB difference in noise when a band is open (at least, when the antenna is not aimed at that building), but I will wait until the band is solidly dead tonight to check that out.
>> My pattern is a form of figure 8 on 40-10 meters, but you are right that you can't maintain the pattern over a greater frequency range.
>> My main point is that there is nothing inherently noisy about a two-wire transmission line!
>> 73,
>> Victor, 4X6GP
>> Rehovot, Israel
>> Formerly K2VCO
>> CWops no. 5
>> http://www.qsl.net/k2vco/
>> On 26-Oct-2019 10:32, Jim Brown wrote:
>>> On 10/25/2019 2:01 PM, Bob McGraw K4TAX wrote:
>>>> Except for my 6M yagi, all of my antennas are non-resonant antennas. My favorite is the 256 ft center fed wire {resonant at 1.825 MHz} with a balanced feed.
>>>
>>> Dean Straw, N6BV, retired editor of the ARRL Antenna Book and Antenna Compendiums, is a very smart engineer and a very good friend. But his promotion of this sort of antenna is probably the greatest error of his time in that job, an idea whose time is LONG past, for many reasons. Primary -- 1) it cannot be choked to kill noise on RX, and 99.9% of hams live surrounded by local noise and 2) it's pattern is different on every frequency.
>>>
>>> I am a strong believer in resonant antennas for each band, if if the must be multi-band antennas like fan dipoles to fit in the available space. For example, a 20/15/10 fan fits in 33 ft and works great, with a predictable pattern on each band. An 80/40 fan works on 15M, with a predictable pattern on both 80 and 40. Hypower Antenna company sells loaded antennas that are resonant on 80 and 40 and fit into about 100 ft; I used one in Chicago on 30 to great effect. All of these antennas are fed with 50 or 75 ohm coax, and CAN be choked to kill RX noise.
>>>
>>> RX noise is a VERY big deal -- if you can't hear 'em, you can't work 'em. If you haven't worked to minimize your RX noise, you're DXing with one hand tied behind your back! My friend AG6EE goes to remote locations in NV, OR, and CA to light up rare grids with 1kW on 6M. Folks trying to work him complain of one-way propagation because he hears them really well and the don't hear him, but the REAL problem is their local RX noise.
>>>
>>> http://k9yc.com/KillingReceiveNoise.pdf Text, NCJ article
>>> http://k9yc.com/KillingRXNoiseVisalia.pdf Slides Visalia talk
>>>
>>> 73, Jim K9YC
>> ______________________________________________________________
>> 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]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Grant Youngman-2

Re: RX noise and 2-wire lines

There is a lot of information here … http://www.lz1aq.signacor.com. I’ve been considering building something along these lines

Grant NQ5T

> On Oct 28, 2019, at 8:04 PM, David Thompson via Elecraft <[hidden email]> wrote:
>
> I would like to know more about your receive antenna. At my home, I deal with S7-S9+ noise and am looking for some way to be able to operate besides FT8.
>
> Thanks…
>
> David Thompson, AG7TX
> Jack of All Trades
> Master of None
> [hidden email]
>
>
>
>
>> On Oct 28, 2019, at 14:31, Drew AF2Z <[hidden email]> wrote:
>>
>> My RX antenna is a pair of small amplified stacked loops. It uses the LZ1AQ amplifier board fed with common FTP (foil twisted pair) cable, which provides the supply voltage, control lines and a shielded twisted pair for the signal. I don't think you can get any better noise isolation than that.
>>
>> It is a lot quieter than my transmitting antennas; lower signal levels as well, but often a better signal-to-noise ratio than the transmit antennas.
>>
>> 73,
>> Drew
>> AF2Z
>>
>>

Drew AF2Z

Re: RX noise and 2-wire lines

In reply to this post by Elecraft mailing list

More info about the LZ1AQ loop preamp is here
http://active-antenna.eu/amplifier-kit/

The supplied amplifier, control board, enclosure, etc. make a nearly
complete package. You fabricate the loop yourself. Various examples are
shown on associated pages.

I think the main benefit of such a small receiving antenna is that you
can localize it away from noise sources in houses or power lines. Even
30 or 40 ft separation might make a difference (the inverse-square law
is your friend!)

The amplifier seems quite robust. My loop + amp is only 25 or 30 ft from
my transmitting antenna and tolerates the 100 watt transmitter output,
no problem. I don't even need any T/R switching; the loop is connected
directly to my K3's RX port or to my RSP1A SDR. Signal levels are safe
on all bands.

It receives well on lower freqs especially-- the AM bcst band and LW. I
can often hear Algeria here in SNJ on winter nights, 252 kHz.

73,
Drew
AF2Z

On 10/28/19 20:04, David Thompson wrote:

> I would like to know more about your receive antenna. At my home, I deal with S7-S9+ noise and am looking for some way to be able to operate besides FT8.
>
> Thanks…
>
> David Thompson, AG7TX
> Jack of All Trades
> Master of None
> [hidden email]
>
>
>
>
>> On Oct 28, 2019, at 14:31, Drew AF2Z <[hidden email]> wrote:
>>
>> My RX antenna is a pair of small amplified stacked loops. It uses the LZ1AQ amplifier board fed with common FTP (foil twisted pair) cable, which provides the supply voltage, control lines and a shielded twisted pair for the signal. I don't think you can get any better noise isolation than that.
>>
>> It is a lot quieter than my transmitting antennas; lower signal levels as well, but often a better signal-to-noise ratio than the transmit antennas.
>>
>> 73,
>> Drew
>> AF2Z
>>
>>
>> On 10/26/19 10:11, Victor Rosenthal 4X6GP wrote:
>>> Jim,
>>> I have to disagree about balanced line. Unlike coax, both conductors are exposed to external RF fields, so common mode noise will be rejected. If the antenna and line are properly balanced (not always easy to do, I admit) and if it is fed through a balanced antenna tuner, there is no reason for it to be noisier than coax. Yes, it can't be choked, but it doesn't need to be.
>>> My antenna is a 10m long rotary dipole fed with open line. It has gone through several iterations and I've been very careful to install the line so that it is perpendicular to the antenna for as far as possible, etc. I've tried various balun arrangements, but the system that works best, both for reducing RF in the shack when transmitting and noise immunity when receiving, is a Johnson kW Matchbox.
>>> There is a building taller than mine a few hundred meters away from it, and a very distinct noise peak when the antenna is turned toward it, which seems to indicate that the noise is picked up by the antenna, not the line. I notice the same noise peak with a coax-fed shielded loop antenna, so it is definitely coming from the building, and isn't an artifact of the alignment of the antenna to the line. I am pretty sure I have at least a 10 dB difference in noise when a band is open (at least, when the antenna is not aimed at that building), but I will wait until the band is solidly dead tonight to check that out.
>>> My pattern is a form of figure 8 on 40-10 meters, but you are right that you can't maintain the pattern over a greater frequency range.
>>> My main point is that there is nothing inherently noisy about a two-wire transmission line!
>>> 73,
>>> Victor, 4X6GP
>>> Rehovot, Israel
>>> Formerly K2VCO
>>> CWops no. 5
>>> http://www.qsl.net/k2vco/
>>> On 26-Oct-2019 10:32, Jim Brown wrote:
>>>> On 10/25/2019 2:01 PM, Bob McGraw K4TAX wrote:
>>>>> Except for my 6M yagi, all of my antennas are non-resonant antennas. My favorite is the 256 ft center fed wire {resonant at 1.825 MHz} with a balanced feed.
>>>>
>>>> Dean Straw, N6BV, retired editor of the ARRL Antenna Book and Antenna Compendiums, is a very smart engineer and a very good friend. But his promotion of this sort of antenna is probably the greatest error of his time in that job, an idea whose time is LONG past, for many reasons. Primary -- 1) it cannot be choked to kill noise on RX, and 99.9% of hams live surrounded by local noise and 2) it's pattern is different on every frequency.
>>>>
>>>> I am a strong believer in resonant antennas for each band, if if the must be multi-band antennas like fan dipoles to fit in the available space. For example, a 20/15/10 fan fits in 33 ft and works great, with a predictable pattern on each band. An 80/40 fan works on 15M, with a predictable pattern on both 80 and 40. Hypower Antenna company sells loaded antennas that are resonant on 80 and 40 and fit into about 100 ft; I used one in Chicago on 30 to great effect. All of these antennas are fed with 50 or 75 ohm coax, and CAN be choked to kill RX noise.
>>>>
>>>> RX noise is a VERY big deal -- if you can't hear 'em, you can't work 'em. If you haven't worked to minimize your RX noise, you're DXing with one hand tied behind your back! My friend AG6EE goes to remote locations in NV, OR, and CA to light up rare grids with 1kW on 6M. Folks trying to work him complain of one-way propagation because he hears them really well and the don't hear him, but the REAL problem is their local RX noise.
>>>>
>>>> http://k9yc.com/KillingReceiveNoise.pdf Text, NCJ article
>>>> http://k9yc.com/KillingRXNoiseVisalia.pdf Slides Visalia talk
>>>>
>>>> 73, Jim K9YC
>>> ______________________________________________________________
>>> Elecraft mailing list
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>>> Help: http://mailman.qth.net/mmfaq.htm
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>>> 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]
>>
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>> Message delivered to [hidden email]
>
>

Bob McGraw - K4TAX

Re: KPA1500 RFI on 12m

In reply to this post by K8TE

Bill:

Glad to see you post this fact.   Hams have had it wrong and doing it
wrong for years, because someone said so.    Many hams seem to have less
than zero knowledge on the topic.    Oh, less than zero knowledge is
knowledge that is not correct.

Same is true when one uses 450 ohm line, many think they need a 4:1
balun because someone said so. I suppose they believe the "4" in 450
ohm line and the "4" in the 4:1 balun ration have something in
common.    Another less than zero knowledge condition.

The electrical length of the wire determines the resonant frequency.
Of course the diameter of the wire contributes to the K factor and bare
wire is different than insulated wire. Thus those two facts must be
considered when cutting an antenna length.   Height above ground {not
necessarily earth because of ground conductivity} determines the feed
point impedance.

Ohhhhh there is so much to learn about antennas.

73

Bob, K4TAX

On 10/27/2019 9:23 PM, K8TE wrote:

> Most hams cut their antenna length for lowest VSWR which is often NOT the
> resonant point. Resonance occurs when XsubL equals XsubC. That means there
> is no reactance at one frequency. Impedance varies greatly with height
> above ground. The greatest radiation occurs at resonance which, again, is
> often not at the lowest VSWR. This is why a good antenna analyzer that
> displays both VSWR and reactance is so helpful.
>
> Web sites abound with advice to cut the antenna for lowest VSWR. Like
> politics, the truth is difficult to find and, apparently, often hard to
> believe. And, anecdotal statements about how an antenna works
> (WORK--WithOut Real Knowledge--K0BG) often has little to do with its
> comparative performance. Too few of us use real data (like WSPRLite) to
> compare antennas and arrive at conclusions based on comparative data.
>
> I liked the Pacificon theme this year: "The Science of Radio" That didn't
> always apply in some of the presentations, but fortunately did in most I
> attended.
>
> 73, Bill, K8TE
>
>

Bob McGraw - K4TAX

Re: RX noise and 2-wire lines

In reply to this post by Lyn WØLEN

Likewise when we lived in a condo in Pompano Beach, FL. I had a 75M
loop around the parapet wall on the roof.   And I managed to get on the
board and got permission.   After all one of the starch objectors wanted
something for him self. Thus a "quid pro quo" was arranged.   Funny how
that works.

I also have a friend that has obtained all the permits to install a
tower and large antenna on his property in a highly restricted HOA in
Boca Raton FL.    It took him 3 years and a few dollars to get all in
order but it was signed off and is presently in place.

It can be done.   Of course it must be done correctly and with proper
documentation and approvals.

Where we live now we have 5 acres but the HOA restrictions are much
tighter.   a.k.a. - Rules of the wife must be followed.

73

Bob, K4TAX

On 10/28/2019 2:45 PM, Lyn Norstad wrote:

> Who ... me? It seems like foreign territory to fall into that category after spending most of my 50 ham years on the other end of the stick.
>
> When I retired a couple years ago, and decided to get serious about ham radio again, I managed to successfully run for a seat on our HOA Board (it's easy ... nobody wants the job). Eventually I was able to get our very strict guidelines changed to allow "reasonable" outside antennas for licensed amateurs. And so far, no complaints on my setup.
>
> Most recently, I have agreed to serve as the Architectural and Landscape Review "committee" so if there is a complaint ... well ... you get the picture.
>
> 73
> Lyn, WØLEN
>
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On Behalf Of Grant Youngman
> Sent: Monday, October 28, 2019 1:54 PM
> To: [hidden email]
> Cc: Elecraft Refl
> Subject: Re: [Elecraft] RX noise and 2-wire lines (was: KPA1500 RFI on 12m)
>
> Don’t you love it when guy’s are taking about their latest large antenna projects? I read these things, look wistfully out back into my 30’x30’ townhouse courtyard, and wonder if I can dare put my Buddipole 40M dipole up one more foot without attracting the ire of some resident who will report my illicit activity to the HOA. That’s about as big as my antenna projects can get 🤣🤣
>
> Grant NQ5T
>
>>
>> On 10/27/2019 11:33 AM, Lyn Norstad wrote:
>>
>>> Your mileage may vary, but for anyone looking to try something new
>>> (actually a very OLD design), it's a fun project.
>> If I had 400 feet for an antenna that's the type of antenna that I would
>> go for too, but I barely have 400 inches. Have fun with the antenna.
>> 73 de K2ASP - Phil Kane
>> Elecraft K2/100 s/n 5402
>>
> ______________________________________________________________
> Elecraft mailing list
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> 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
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Don Wilhelm

Re: KPA1500 RFI on 12m

In reply to this post by Bob McGraw - K4TAX

For all interested, you might want to read the relevant article on my
website www.w3fpr.com. It was written directed at QRP ops, but applies
to QRO operations as well.

73,
Don W3FPR

On 10/29/2019 7:56 PM, Bob McGraw K4TAX wrote:

> Bill:
>
> Glad to see you post this fact.   Hams have had it wrong and doing it
> wrong for years, because someone said so.    Many hams seem to have less
> than zero knowledge on the topic.    Oh, less than zero knowledge is
> knowledge that is not correct.
>
> Same is true when one uses 450 ohm line, many think they need a 4:1
> balun because someone said so. I suppose they believe the "4" in 450
> ohm line and the "4" in the 4:1 balun ration have something in
> common.    Another less than zero knowledge condition.
>
> The electrical length of the wire determines the resonant frequency. Of
> course the diameter of the wire contributes to the K factor and bare
> wire is different than insulated wire. Thus those two facts must be
> considered when cutting an antenna length.   Height above ground {not
> necessarily earth because of ground conductivity} determines the feed
> point impedance.
>
> Ohhhhh there is so much to learn about antennas.
>
> 73
>
> Bob, K4TAX
>
>
>
>
> On 10/27/2019 9:23 PM, K8TE wrote:
>> Most hams cut their antenna length for lowest VSWR which is often NOT the
>> resonant point. Resonance occurs when XsubL equals XsubC. That means
>> there
>> is no reactance at one frequency. Impedance varies greatly with height
>> above ground. The greatest radiation occurs at resonance which,
>> again, is
>> often not at the lowest VSWR. This is why a good antenna analyzer that
>> displays both VSWR and reactance is so helpful.
>>
>> Web sites abound with advice to cut the antenna for lowest VSWR. Like
>> politics, the truth is difficult to find and, apparently, often hard to
>> believe. And, anecdotal statements about how an antenna works
>> (WORK--WithOut Real Knowledge--K0BG) often has little to do with its
>> comparative performance. Too few of us use real data (like WSPRLite) to
>> compare antennas and arrive at conclusions based on comparative data.
>>
>> I liked the Pacificon theme this year: "The Science of Radio" That
>> didn't
>> always apply in some of the presentations, but fortunately did in most I
>> attended.
>>
>> 73, Bill, K8TE
>>
>>
>
> ______________________________________________________________
> 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]

Eric Swartz - WA6HHQ

Re: KPA1500 RFI on 12m

Administrator

And with that post, lets close this -very- long thread.

-Please- self moderate and end discussion threads when they get too long in the interest of relieving email overload for our other readers. Once a thread hits 10 to 15 postings it should be voluntarily ended with very few additional emails. If you feel the need to make additional 'last' comments, please make them off list to direct email.

73,
Eric
Moderator, from time to time.
elecraft.com
_..._

> On Oct 29, 2019, at 7:14 PM, Don Wilhelm <[hidden email]> wrote:
>
> For all interested, you might want to read the relevant article on my website www.w3fpr.com. It was written directed at QRP ops, but applies to QRO operations as well.
______________________________________________________________
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