static buildup on antennas

[djl]

An antenna can get charged up in different ways. First, the earth has a
fair-weather electric field of about 100 v/m near the ground. This field
has a very high source impedance, so most things simply look like short
circuits. If, however, an antenna is left disconnected that is not
shorted, it will come to equilibrium with this static field and charge
up according to its capacitance. The charge will probably bleed off, but
not always. During high winds, especially with dust or snow, or even
rain, the charge on the antenna can become very much larger. The reason
for this is that not only can the particles, charged by friction,
transfer charge to the antenna, but also particles leaving a conductor
in the presence of a static field carry charge away from the conductor,
leaving the opposite charge on the conductor. This is why the exhaust of
a helicopter or aircraft can charge it up.
Because antennas are raised above the ground, the fair weather electric
fields can reach high values at the top of towers or other supports, and
the horizontal elements of wire antennas as well. For example, a 30 m
tower can have a field near its top of 3000 v/m. In addition, there is a
shape factor that can raise this value even further. Then, any sharp
point can go into corona discharge, so small currents will flow. This
means any wire ends not covered with tape or blobs of insulating goop
will generate small steady currents.
All of these static effects can easily be taken care of by simply
putting a 5k resistor to ground at the antenna terminations, either at
the antenna itself or at switching points, etc. A good friend and I have
K2's and suffered routine blowouts of the swr sensor diodes for these
reasons until we put 1/2 w 5k resistors on the inputs. no more problems.
During a thunderstorm, the static electric fields near the ground can
get as high as 5000 v/m or even more, depending on the arrangement of
the clouds with respect to your location. This means that the buildup of
charge on antennas as described above can reach really high values.
However, this static buildup will still be sufficiently taken care of by
the resistance trick as above.
Now we come to the other problem, induced pulses from lightning. As you
all know, the lightning discharge, whether in cloud or to ground is from
our point of view a huge antenna. The radiation peaks at about 1-5 MHz,
but there are components for various reasons well into the VHF region.
Proper antenna mast and antenna treatments can be found in the
literature so I won't go into that. Find some good articles and follow
their advice. One main thing to remember is to keep all mitigating
switches, arc points, and their grounding stuff outside the shack. In
case of a direct hit to any part of the antenna system, you don't want
it inside!

I hope this helps somewhat. More on the earth's fair weather field can
no doubt be found online.
73, Don


--
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
De Erroribus Medicorum, R. Bacon, 13th century.
"If you don't know what it is, don't poke it."
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com


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[Gary Bartlett VE1RGB]

Can someone comment on this issue as it relates to balanced wire antennas
like dipoles fed with ladder line and matched to a K3 receiver through a
balun?  Is the problem with discharges from precipitation and other static
electricity sources with that feed configuration the same as for coax feed?
(Yes, I recognize, lightning would be a different issue.)   For that matter,
how does the K3 transmatch figure into the equation in terms of protecting
the receiver from unfriendly charge build-ups (both when the radio is
powered up and when powered off)?  

If the concerns are the same for both types of transmission line, what is
the protection configuration external to the radio for the ladderline
situation?

73,
Gary VE1RGB

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Don Latham
Sent: September 10, 2012 2:35 PM
To: [hidden email]
Subject: [Elecraft] static buildup on antennas

An antenna can get charged up in different ways. First, the earth has a
fair-weather electric field of about 100 v/m near the ground. This field
has a very high source impedance, so most things simply look like short
circuits. If, however, an antenna is left disconnected that is not
shorted, it will come to equilibrium with this static field and charge
up according to its capacitance. The charge will probably bleed off, but
not always. During high winds, especially with dust or snow, or even
rain, the charge on the antenna can become very much larger. The reason
for this is that not only can the particles, charged by friction,
transfer charge to the antenna, but also particles leaving a conductor
in the presence of a static field carry charge away from the conductor,
leaving the opposite charge on the conductor. This is why the exhaust of
a helicopter or aircraft can charge it up.
Because antennas are raised above the ground, the fair weather electric
fields can reach high values at the top of towers or other supports, and
the horizontal elements of wire antennas as well. For example, a 30 m
tower can have a field near its top of 3000 v/m. In addition, there is a
shape factor that can raise this value even further. Then, any sharp
point can go into corona discharge, so small currents will flow. This
means any wire ends not covered with tape or blobs of insulating goop
will generate small steady currents.
All of these static effects can easily be taken care of by simply
putting a 5k resistor to ground at the antenna terminations, either at
the antenna itself or at switching points, etc. A good friend and I have
K2's and suffered routine blowouts of the swr sensor diodes for these
reasons until we put 1/2 w 5k resistors on the inputs. no more problems.
During a thunderstorm, the static electric fields near the ground can
get as high as 5000 v/m or even more, depending on the arrangement of
the clouds with respect to your location. This means that the buildup of
charge on antennas as described above can reach really high values.
However, this static buildup will still be sufficiently taken care of by
the resistance trick as above.
Now we come to the other problem, induced pulses from lightning. As you
all know, the lightning discharge, whether in cloud or to ground is from
our point of view a huge antenna. The radiation peaks at about 1-5 MHz,
but there are components for various reasons well into the VHF region.
Proper antenna mast and antenna treatments can be found in the
literature so I won't go into that. Find some good articles and follow
their advice. One main thing to remember is to keep all mitigating
switches, arc points, and their grounding stuff outside the shack. In
case of a direct hit to any part of the antenna system, you don't want
it inside!

I hope this helps somewhat. More on the earth's fair weather field can
no doubt be found online.
73, Don


--
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
De Erroribus Medicorum, R. Bacon, 13th century.
"If you don't know what it is, don't poke it."
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com


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[Don Wilhelm-4]

Gary,

The type of transmission line does not matter, there will be static
buildup on the antenna wires, pure and simple.  That is conducted into
the shack by the transmission line, whether that be coax or balanced line.

I am sorry I did not make that clear previously.  Most transceivers use
coax input, and as long as the problem is solved before the coax reaches
the transceiver, there is no remaining problem.

Yes. a resistor across the balanced feedline will be sufficient.

73,
Don W3FPR

On 9/10/2012 2:19 PM, gary bartlett wrote:

> Can someone comment on this issue as it relates to balanced wire antennas
> like dipoles fed with ladder line and matched to a K3 receiver through a
> balun?  Is the problem with discharges from precipitation and other static
> electricity sources with that feed configuration the same as for coax feed?
> (Yes, I recognize, lightning would be a different issue.)   For that matter,
> how does the K3 transmatch figure into the equation in terms of protecting
> the receiver from unfriendly charge build-ups (both when the radio is
> powered up and when powered off)?
>
> If the concerns are the same for both types of transmission line, what is
> the protection configuration external to the radio for the ladderline
> situation?
>
> 73,
> Gary VE1RGB
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Don Latham
> Sent: September 10, 2012 2:35 PM
> To: [hidden email]
> Subject: [Elecraft] static buildup on antennas
>
> An antenna can get charged up in different ways. First, the earth has a
> fair-weather electric field of about 100 v/m near the ground. This field
> has a very high source impedance, so most things simply look like short
> circuits. If, however, an antenna is left disconnected that is not
> shorted, it will come to equilibrium with this static field and charge
> up according to its capacitance. The charge will probably bleed off, but
> not always. During high winds, especially with dust or snow, or even
> rain, the charge on the antenna can become very much larger. The reason
> for this is that not only can the particles, charged by friction,
> transfer charge to the antenna, but also particles leaving a conductor
> in the presence of a static field carry charge away from the conductor,
> leaving the opposite charge on the conductor. This is why the exhaust of
> a helicopter or aircraft can charge it up.
> Because antennas are raised above the ground, the fair weather electric
> fields can reach high values at the top of towers or other supports, and
> the horizontal elements of wire antennas as well. For example, a 30 m
> tower can have a field near its top of 3000 v/m. In addition, there is a
> shape factor that can raise this value even further. Then, any sharp
> point can go into corona discharge, so small currents will flow. This
> means any wire ends not covered with tape or blobs of insulating goop
> will generate small steady currents.
> All of these static effects can easily be taken care of by simply
> putting a 5k resistor to ground at the antenna terminations, either at
> the antenna itself or at switching points, etc. A good friend and I have
> K2's and suffered routine blowouts of the swr sensor diodes for these
> reasons until we put 1/2 w 5k resistors on the inputs. no more problems.
> During a thunderstorm, the static electric fields near the ground can
> get as high as 5000 v/m or even more, depending on the arrangement of
> the clouds with respect to your location. This means that the buildup of
> charge on antennas as described above can reach really high values.
> However, this static buildup will still be sufficiently taken care of by
> the resistance trick as above.
> Now we come to the other problem, induced pulses from lightning. As you
> all know, the lightning discharge, whether in cloud or to ground is from
> our point of view a huge antenna. The radiation peaks at about 1-5 MHz,
> but there are components for various reasons well into the VHF region.
> Proper antenna mast and antenna treatments can be found in the
> literature so I won't go into that. Find some good articles and follow
> their advice. One main thing to remember is to keep all mitigating
> switches, arc points, and their grounding stuff outside the shack. In
> case of a direct hit to any part of the antenna system, you don't want
> it inside!
>
> I hope this helps somewhat. More on the earth's fair weather field can
> no doubt be found online.
> 73, Don
>
>

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Gary,
My antenna tuner has a 4:1 current balun built in.  The DC resistance across the ladder line is near zero ohms.  I would think that would bleed off any charge.
73,
Art  WB8ENE

---------- Original Message ----------
From: gary bartlett <[hidden email]>
To: [hidden email]
Subject: Re: [Elecraft] static buildup on antennas
Date: Mon, 10 Sep 2012 15:19:04 -0300

Can someone comment on this issue as it relates to balanced wire antennas
like dipoles fed with ladder line and matched to a K3 receiver through a
balun?  Is the problem with discharges from precipitation and other static
electricity sources with that feed configuration the same as for coax feed?
(Yes, I recognize, lightning would be a different issue.)   For that matter,
how does the K3 transmatch figure into the equation in terms of protecting
the receiver from unfriendly charge build-ups (both when the radio is
powered up and when powered off)?  

If the concerns are the same for both types of transmission line, what is
the protection configuration external to the radio for the ladderline
situation?

73,
Gary VE1RGB

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Don Latham
Sent: September 10, 2012 2:35 PM
To: [hidden email]
Subject: [Elecraft] static buildup on antennas

An antenna can get charged up in different ways. First, the earth has a
fair-weather electric field of about 100 v/m near the ground. This field
has a very high source impedance, so most things simply look like short
circuits. If, however, an antenna is left disconnected that is not
shorted, it will come to equilibrium with this static field and charge
up according to its capacitance. The charge will probably bleed off, but
not always. During high winds, especially with dust or snow, or even
rain, the charge on the antenna can become very much larger. The reason
for this is that not only can the particles, charged by friction,
transfer charge to the antenna, but also particles leaving a conductor
in the presence of a static field carry charge away from the conductor,
leaving the opposite charge on the conductor. This is why the exhaust of
a helicopter or aircraft can charge it up.
Because antennas are raised above the ground, the fair weather electric
fields can reach high values at the top of towers or other supports, and
the horizontal elements of wire antennas as well. For example, a 30 m
tower can have a field near its top of 3000 v/m. In addition, there is a
shape factor that can raise this value even further. Then, any sharp
point can go into corona discharge, so small currents will flow. This
means any wire ends not covered with tape or blobs of insulating goop
will generate small steady currents.
All of these static effects can easily be taken care of by simply
putting a 5k resistor to ground at the antenna terminations, either at
the antenna itself or at switching points, etc. A good friend and I have
K2's and suffered routine blowouts of the swr sensor diodes for these
reasons until we put 1/2 w 5k resistors on the inputs. no more problems.
During a thunderstorm, the static electric fields near the ground can
get as high as 5000 v/m or even more, depending on the arrangement of
the clouds with respect to your location. This means that the buildup of
charge on antennas as described above can reach really high values.
However, this static buildup will still be sufficiently taken care of by
the resistance trick as above.
Now we come to the other problem, induced pulses from lightning. As you
all know, the lightning discharge, whether in cloud or to ground is from
our point of view a huge antenna. The radiation peaks at about 1-5 MHz,
but there are components for various reasons well into the VHF region.
Proper antenna mast and antenna treatments can be found in the
literature so I won't go into that. Find some good articles and follow
their advice. One main thing to remember is to keep all mitigating
switches, arc points, and their grounding stuff outside the shack. In
case of a direct hit to any part of the antenna system, you don't want
it inside!

I hope this helps somewhat. More on the earth's fair weather field can
no doubt be found online.
73, Don


--
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
De Erroribus Medicorum, R. Bacon, 13th century.
"If you don't know what it is, don't poke it."
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com


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[Don Wilhelm-4]

Yes, link coupled tuners will solve a lot of those problems.  There is
no DC path from the antenna to the transceiver.
However, those link coupled tuners have been disappearing from the face
of the earth at a rapid rate.  They are not easily band-switched (the
Johnson Matchbox units were an attempt, but the matching rang was limited)/

73,\
Don W3FPR


On 9/10/2012 2:31 PM, Ron D'Eau Claire wrote:

> It gets tricky when the antenna feed point impedance is several thousand
> ohms such as I see with my 130 foot inverted L on 80 meters or with the
> common open wire fed multiband doublets.
>
> In those cases it's common to use a resistance of 100K or more to avoid
> excessive losses in the resistors.
>
> But, such large resistances require more time to bleed off the accumulated
> voltage. At some point they can no longer drain the charge as fast as it
> accumulates and become ineffective.
>
> My favorite "tuner" for such antennas has always been a link-coupled tuner.
> No direct-current connection between the antenna and the rig and a d-c path
> to ground for the antenna at all times. But such tuners are not conducive to
> fast, automatic operation.
>
> 73, Ron AC7AC
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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[Bill K9YEQ]

Don,  

Did I not see a picture of your shack with a Matchbox, or am I thinking of
someone else?  

As sweet as the link coupling is, I would think a servo controlled box could
be designed as an automatic unit... perhaps Wayne could be talked into
designing one starting at QRP level and eventually designing a QRO linker.

73,
Bill
K9YEQ


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Don Wilhelm
Sent: Monday, September 10, 2012 1:46 PM
To: Ron D'Eau Claire
Cc: [hidden email]
Subject: Re: [Elecraft] static buildup on antennas

Yes, link coupled tuners will solve a lot of those problems.  There is no DC
path from the antenna to the transceiver.
However, those link coupled tuners have been disappearing from the face of
the earth at a rapid rate.  They are not easily band-switched (the Johnson
Matchbox units were an attempt, but the matching rang was limited)/

73,\
Don W3FPR


On 9/10/2012 2:31 PM, Ron D'Eau Claire wrote:

> It gets tricky when the antenna feed point impedance is several
> thousand ohms such as I see with my 130 foot inverted L on 80 meters
> or with the common open wire fed multiband doublets.
>
> In those cases it's common to use a resistance of 100K or more to
> avoid excessive losses in the resistors.
>
> But, such large resistances require more time to bleed off the
> accumulated voltage. At some point they can no longer drain the charge
> as fast as it accumulates and become ineffective.
>
> My favorite "tuner" for such antennas has always been a link-coupled

tuner.

> No direct-current connection between the antenna and the rig and a d-c
> path to ground for the antenna at all times. But such tuners are not
> conducive to fast, automatic operation.
>
> 73, Ron AC7AC
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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> list: http://www.qsl.net/donate.html
>

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[Chuck N4XS]

> -----Original Message-----
> From: [hidden email]
> Subject: Re: [Elecraft] static buildup on antennas
>
> Gary,
> My antenna tuner has a 4:1 current balun built in.  The DC resistance
across
> the ladder line is near zero ohms.  I would think that would bleed off any
charge.
> 73,
> Art  WB8ENE

Any balun that has a DC path between the center conductor and shield will
take care of the static buildup problem. Balun designs vary, but all the 4:1
current baluns I have do have that DC path. If you aren't sure what's inside
a balun, you can make a quick check with an ohmmeter. A reading of near zero
ohms between the center conductor and the shell tells you that the DC path
is there.

Chuck N4XS


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[k6dgw]

Comments interspersed since you asked questions.

On 9/10/2012 11:19 AM, gary bartlett wrote:
> Can someone comment on this issue as it relates to balanced wire antennas
> like dipoles fed with ladder line and matched to a K3 receiver through a
> balun?

Doesn't matter, so long as the antenna is not at DC ground.  A grounded,
shunt fed tower is at DC ground.  A dipole strung between it and an
organic tower isn't.

> Is the problem with discharges from precipitation and other static
> electricity sources with that feed configuration the same as for coax feed?

Essentially, yes.

> (Yes, I recognize, lightning would be a different issue.)   For that matter,
> how does the K3 transmatch figure into the equation in terms of protecting
> the receiver from unfriendly charge build-ups (both when the radio is
> powered up and when powered off)?

Powered or non-powered, doesn't matter.  My K3 has a static bleed
resistor inside, I also have 100K's [I think, maybe 50K] on coax tee's
on the antenna connectors.
>
> If the concerns are the same for both types of transmission line, what is
> the protection configuration external to the radio for the ladderline
> situation?

Well, pretty much the same only not quite as convenient as the
PL-259/coax tee solution.  Just put a 100K to ground from both sides of
the balanced line.  If you have a balun in your configuration, it's
possible that it will DC ground your antenna through a center-tap.  It's
easy enough to test.

We can talk this into way more of a problem than it really is, as Don
mentioned, and possibly is happening.  The so called "fair weather
field" of 100-200 V/m means nothing, its source impedance is so high
that it delivers essentially zero current.  I'm 6'2" [1.87m] so standing
outside, the potential of my head should be a few hundred volts above my
feet.  In fact, I'm a short circuit and it is zero or extremely close to it.

Precip static is a problem only if your antenna input on the radio is DC
insulated from ground.  The individual charges deposited in the antenna
are very tiny but they add up in the input capacitance and the potential
slowly ratchets up.

The no-more-stress solution is just put a bleed resistor on all your
antennas, leave it there, and move on to working NH8S on all bands. :-)

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org

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[Don Wilhelm-4]

Bill,

I do have a Matchbox, but it is not in the shack, All my antennas are
resonant, so there is no need for a tuner at the home QTH.   The
Matchbox serves an an artificial antenna, if I need to devise some
strange load to an Elecraft K1, K2, KX1 that I am in process of
repairing.  Often times a bandpass filter at a specific frequency is
needed, and the Matchbox provides that quite nicely.

73,
Don W3FPR

On 9/10/2012 3:37 PM, Bill K9YEQ wrote:

> Don,
>
> Did I not see a picture of your shack with a Matchbox, or am I thinking of
> someone else?
>
> As sweet as the link coupling is, I would think a servo controlled box could
> be designed as an automatic unit... perhaps Wayne could be talked into
> designing one starting at QRP level and eventually designing a QRO linker.
>
> 73,
> Bill
> K9YEQ
>
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Don Wilhelm
> Sent: Monday, September 10, 2012 1:46 PM
> To: Ron D'Eau Claire
> Cc: [hidden email]
> Subject: Re: [Elecraft] static buildup on antennas
>
> Yes, link coupled tuners will solve a lot of those problems.  There is no DC
> path from the antenna to the transceiver.
> However, those link coupled tuners have been disappearing from the face of
> the earth at a rapid rate.  They are not easily band-switched (the Johnson
> Matchbox units were an attempt, but the matching rang was limited)/
>
> 73,\
> Don W3FPR
>
>
> On 9/10/2012 2:31 PM, Ron D'Eau Claire wrote:
>> It gets tricky when the antenna feed point impedance is several
>> thousand ohms such as I see with my 130 foot inverted L on 80 meters
>> or with the common open wire fed multiband doublets.
>>
>> In those cases it's common to use a resistance of 100K or more to
>> avoid excessive losses in the resistors.
>>
>> But, such large resistances require more time to bleed off the
>> accumulated voltage. At some point they can no longer drain the charge
>> as fast as it accumulates and become ineffective.
>>
>> My favorite "tuner" for such antennas has always been a link-coupled
> tuner.
>> No direct-current connection between the antenna and the rig and a d-c
>> path to ground for the antenna at all times. But such tuners are not
>> conducive to fast, automatic operation.
>>
>> 73, Ron AC7AC
>>
>>
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[Gary Bartlett VE1RGB]

Thanks, everyone.  Perhaps I should have emphasised the word *balun* in my
original post by describing what I was using.  I modified an MFJ-949
transmatch by replacing the original 4:1 balun by a 9:1 Guanella.  One
terminal of each side of that balun transformer is/was tied to ground in
either case.

73,
Gary VE1RGB

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Fred Jensen
Sent: September 10, 2012 5:01 PM
To: [hidden email]
Subject: Re: [Elecraft] static buildup on antennas

Comments interspersed since you asked questions.

On 9/10/2012 11:19 AM, gary bartlett wrote:
> Can someone comment on this issue as it relates to balanced wire antennas
> like dipoles fed with ladder line and matched to a K3 receiver through a
> balun?

Doesn't matter, so long as the antenna is not at DC ground.  A grounded,
shunt fed tower is at DC ground.  A dipole strung between it and an
organic tower isn't.

> Is the problem with discharges from precipitation and other static
> electricity sources with that feed configuration the same as for coax
feed?

Essentially, yes.

> (Yes, I recognize, lightning would be a different issue.)   For that
matter,
> how does the K3 transmatch figure into the equation in terms of protecting
> the receiver from unfriendly charge build-ups (both when the radio is
> powered up and when powered off)?

Powered or non-powered, doesn't matter.  My K3 has a static bleed
resistor inside, I also have 100K's [I think, maybe 50K] on coax tee's
on the antenna connectors.
>
> If the concerns are the same for both types of transmission line, what is
> the protection configuration external to the radio for the ladderline
> situation?

Well, pretty much the same only not quite as convenient as the
PL-259/coax tee solution.  Just put a 100K to ground from both sides of
the balanced line.  If you have a balun in your configuration, it's
possible that it will DC ground your antenna through a center-tap.  It's
easy enough to test.

We can talk this into way more of a problem than it really is, as Don
mentioned, and possibly is happening.  The so called "fair weather
field" of 100-200 V/m means nothing, its source impedance is so high
that it delivers essentially zero current.  I'm 6'2" [1.87m] so standing
outside, the potential of my head should be a few hundred volts above my
feet.  In fact, I'm a short circuit and it is zero or extremely close to it.

Precip static is a problem only if your antenna input on the radio is DC
insulated from ground.  The individual charges deposited in the antenna
are very tiny but they add up in the input capacitance and the potential
slowly ratchets up.

The no-more-stress solution is just put a bleed resistor on all your
antennas, leave it there, and move on to working NH8S on all bands. :-)

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org

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[Richard Fjeld]

I know there are differences of opinion on this, but I have come to believe
if I can keep a static charge from building up on my antennas, and other
devices, it will greatly lessen the chance of a dis-charge occurring.  I
even ground the metal vent pipe that goes up through the roof of my house,
as well as the downspouts from my rain gutters.

I have alligator clips on the ends of my ladder-line so that I can easily
connect them to a ground lead when finished operating. I would get bit doing
this at times, so I put a 1 MegOhm resistor from each twin lead tap on the
tuner to ground. No trouble since.  Perhaps I should reduce the R value
though.
Some guys use spark plugs to bleed off, but I feel that allows too much
voltage at the point of dis-charge.

Now this, and I will be brief. I saw where lightning hit a decorative
electric light about five feet high on the front lawn of a house. You would
think that would have been an adequate path to ground. Instead, it followed
the buried wire that ran from it, under the blacktop driveway, throwing the
asphalt up on the roof of the house. It went into the house and did all
kinds of havoc. I suppose the metal light post was just stuck into the
ground a couple feet or so. It isn't just our antennas that need grounding.


----- Original Message -----
From: <[hidden email]>
To: <[hidden email]>
Cc: <[hidden email]>
Sent: Monday, September 10, 2012 1:43 PM
Subject: Re: [Elecraft] static buildup on antennas


> Gary,
> My antenna tuner has a 4:1 current balun built in.  The DC resistance
> across the ladder line is near zero ohms.  I would think that would bleed
> off any charge.
> 73,
> Art  WB8ENE
>
>

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[Dr. William J. Schmidt, II]

In a related matter, I recently ran across a bountiful supply of new design,
high amperage, reasonably priced knife switches on eBay.  If you make the
switched conductor the radio and the two stationary terminals "Antenna" and
"Ground", it's trivial to disconnect your antenna/ Set the input of your
radio to ground for storms.  Search for "Knife Disconnect Switch".


Dr. William J. Schmidt - K9HZ / J68HZ/ 8P6HK/ ZF2HZ

Owner - Operator
Big Signal Ranch
Staunton, Illinois

email:  [hidden email]


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Richard Fjeld
Sent: Tuesday, September 11, 2012 1:19 PM
To: elecraft posting
Subject: Re: [Elecraft] static buildup on antennas

I know there are differences of opinion on this, but I have come to believe
if I can keep a static charge from building up on my antennas, and other
devices, it will greatly lessen the chance of a dis-charge occurring.  I
even ground the metal vent pipe that goes up through the roof of my house,
as well as the downspouts from my rain gutters.

I have alligator clips on the ends of my ladder-line so that I can easily
connect them to a ground lead when finished operating. I would get bit doing
this at times, so I put a 1 MegOhm resistor from each twin lead tap on the
tuner to ground. No trouble since.  Perhaps I should reduce the R value
though.
Some guys use spark plugs to bleed off, but I feel that allows too much
voltage at the point of dis-charge.

Now this, and I will be brief. I saw where lightning hit a decorative
electric light about five feet high on the front lawn of a house. You would
think that would have been an adequate path to ground. Instead, it followed
the buried wire that ran from it, under the blacktop driveway, throwing the
asphalt up on the roof of the house. It went into the house and did all
kinds of havoc. I suppose the metal light post was just stuck into the
ground a couple feet or so. It isn't just our antennas that need grounding.


----- Original Message -----
From: <[hidden email]>
To: <[hidden email]>
Cc: <[hidden email]>
Sent: Monday, September 10, 2012 1:43 PM
Subject: Re: [Elecraft] static buildup on antennas


> Gary,
> My antenna tuner has a 4:1 current balun built in.  The DC resistance
> across the ladder line is near zero ohms.  I would think that would bleed
> off any charge.
> 73,
> Art  WB8ENE
>
>

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[Don Wilhelm-4]

That same thing can be done almost automatically with relays (and a
little thoughtful design).  My in-shack relay switching system selects
between 3 inbound feedlines and routes them to one of 3 transceivers.  
The K3 gets the 1st priority choice, and the 2nd transceiver (either the
KX3 or the FT-847) gets the 2nd choice.  The 3rd choice is routed either
to an auxiliary transceiver or to the workbench location (usually the
workbench).  When the relay power is turned off or no antenna is
selected for either transceiver, the input is connected to a dummy load.

That is not to diminish the knife switch solution - while it is manual,
it works, and works very well.  That takes me back to my novice days
when the T-R switch was a knife switch.  Sometimes simplest is the best.

73,
Don W3FPR.


On 9/11/2012 8:07 PM, Dr. William J. Schmidt, II wrote:
> In a related matter, I recently ran across a bountiful supply of new design,
> high amperage, reasonably priced knife switches on eBay.  If you make the
> switched conductor the radio and the two stationary terminals "Antenna" and
> "Ground", it's trivial to disconnect your antenna/ Set the input of your
> radio to ground for storms.  Search for "Knife Disconnect Switch".
>
>
> Dr. William J. Schmidt - K9HZ / J68HZ/ 8P6HK/ ZF2HZ
>

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[Dr. William J. Schmidt, II]

That's even easier.  Every antenna you buy/ make/ put up should be DC to
ground.  That's antennas 101.

 

I dunno if I like relays either. extra copper path back to the shack.

 

 

Dr. William J. Schmidt - K9HZ / J68HZ/ 8P6HK/ ZF2HZ/ PJ4HZ

 

Owner - Operator

Big Signal Ranch

Staunton, Illinois

 

email:  [hidden email]

 

From: [hidden email] [mailto:[hidden email]] On Behalf Of Hank
Garretson
Sent: Tuesday, September 11, 2012 7:24 PM
To: [hidden email]
Subject: Re: [Elecraft] static buildup on antennas

 


Those talking about relays and switches are perhaps missing half the
equation.

Switches and relays, done correctly, may protect your transceiver.

Switches or relays that short or ground do not get rid of participation
static.

As has been suggested by many, best bet is to use a high-ohm resistor across
feedline at shack entry. For open-wire line, from each side to antenna tuner
case. For coax from center conductor to shield.

This approach solves both transceiver-protection and participation-static
problems.

Note, this approach does not provide lightning protection, which is another
subject.


Ski Exuberantly,

Hank, W6SX

Mammoth Lakes, California

Elevation 8083 feet in John Muir's Range of Light

  _____  

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[Mike Schwendeman]

Richard;

You had offered the following:
 > I have alligator clips on the ends of my ladder-line so that I can
easily connect them
 > to a ground lead when finished operating. I would get bit doing this
at times, so I put
 > a 1 MegOhm resistor from each twin lead tap on the tuner to ground.
No trouble since.
 > Perhaps I should reduce the R value though.
 > Some guys use spark plugs to bleed off, but I feel that allows too
much voltage at the point of dis-charge.

I suggest that you attach the alligator clips to your GROUNDED wires,
not the antenna.  (Safety is the thought, here.)

One meg of resistance as a bleeder is a good thought, but might be
"plenty high."  (Consider a value closer to a quarter-meg, per what I
recall reading.)

I agree that the spark-plug is basically a good thought, but is this gap
is jumped, the receiver may well have suffered damage at that point.  
Not a total protection situation!

If one uses a balun, the antenna (considering balanced line) is grounded
as a result of the balun's DC continuity.  This seems to satisfy a lot
of needs...  It may be that SOME baluns do not offer a DC path to the
coax, but mine do.

73;    -Mike-    KØJTA
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