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[OT] Grounding Antenna when not in use

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Chuck Teeter KE9CE

[OT] Grounding Antenna when not in use

Hello:

After I get my kit built, I¹ll be operating with a windom antenna on 40
10. It¹s been suggested that when I¹m not operating, I should disconnect
the rig from the antenna and run the antenna to ground. I¹ve never done
that in the past when I operated with wire antennas or my vertical, but it
does make sense as a safety precaution. I¹m wondering if anyone has any
suggestions about the best way(s) to do that? Are there any pieces of
equipment that you would recommend to simplify the process? Any help would
be greatly appreciated. Thanks.

73,
Chuck KE9CE
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Stephen W. Kercel

Re: [OT] Grounding Antenna when not in use

A ground bus from The Wireman greatly simplifies the process.

73,

Steve Kercel
AA4AK

Charles Teeter wrote:

> Hello:
>
> After I get my kit built, I¹ll be operating with a windom antenna on 40
> 10. It¹s been suggested that when I¹m not operating, I should disconnect
> the rig from the antenna and run the antenna to ground. I¹ve never done
> that in the past when I operated with wire antennas or my vertical, but it
> does make sense as a safety precaution. I¹m wondering if anyone has any
> suggestions about the best way(s) to do that? Are there any pieces of
> equipment that you would recommend to simplify the process? Any help would
> be greatly appreciated. Thanks.
>
> 73,
> Chuck KE9CE
> ______________________________________________________________
> Elecraft mailing list
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>

Mel

Re: [OT] Grounding Antenna when not in use

I might make a suggestion. It is terribly easy to forget to throw the switch. What I do when I need such a precaution, I put a 20 A SPST 12VDC coil relay connected to the switched 12 VDC output. When the K3 is is the energized mode the antenna is passed to the K3, when the K3 is off, the antenna is grounded.

Mel, K6KBE

--- On Fri, 3/19/10, Stephen W. Kercel <[hidden email]> wrote:

From: Stephen W. Kercel <[hidden email]>
Subject: Re: [Elecraft] [OT] Grounding Antenna when not in use
To: "Charles Teeter" <[hidden email]>
Cc: [hidden email]
Date: Friday, March 19, 2010, 3:19 PM

A ground bus from The Wireman greatly simplifies the process.

73,

Steve Kercel
AA4AK

Charles Teeter wrote:

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Phil Salas

Re: [OT] Grounding Antenna when not in use

I use a MFJ-4726/4726RC powered 6x6 port antenna switch. All non-selected inputs are always grounded, and the unit automatically grounds everything when you shut off power, or when you turn off your transceiver.

Phil - AD5X
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W8JI

Re: [OT] Grounding Antenna when not in use

In reply to this post by Chuck Teeter KE9CE

After I get my kit built, I¹ll be operating with a windom
antenna on 40
10. It¹s been suggested that when I¹m not operating, I
should disconnect
the rig from the antenna and run the antenna to ground.
I¹ve never done
that in the past when I operated with wire antennas or my
vertical, but it
does make sense as a safety precaution. I¹m wondering if
anyone has any
suggestions about the best way(s) to do that? Are there any
pieces of
equipment that you would recommend to simplify the process?
Any help would
be greatly appreciated. Thanks.>>

Chuck,

Nearly all the time when there is serious damage, it comes
from a loop from power lines to your antenna and station
ground.

http://www.w8ji.com/ground_systems.htm

You either MUST have a proper station ground bonded to the
power mains ground and a bulkhead entrance, or you really
would have to take the rig totally out of line. No power
supply connections, computer connections, antenna, or
anything.

Although it is popular, grounding the antenna when off
really means next to nothing. It can help if a hit is a mile
away, or from p-static charging, but it won't do a thing if
lightning hits the mains (very common) or the antenna (very
rare unless you have a tall tower).

For automatic antenna disconnect and static shielding you
really need a double-make double-break relay, in a proper
box with proper layout, to totally isolate the center
conductor. It has to be a properly configured double-make
double-break that grounds the transfer bar when the relay is
off. Any other type of relay or switch is not secure at all.

Tom

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Bob Naumann W5OV

Re: [OT] Grounding Antenna when not in use

Well,

I guess I've had some very rare hits since my TA33 at 25' on my parent's
home years ago got hit by lightning and my Cushcraft R7000 vertical mounted
at 10' above the ground got hit just 5 years ago here in Texas. My radios
were disconnected from the feedline, but still connected to everything else.
No damage in the shack in either case except during the recent hit, my DSL
modem was taken out.

My neighbor's wife happened to be looking out her kitchen window and saw the
lightning hit the vertical. The coax feedline to the antenna went down to
ground level, next to my pool filter motor and then into the house. The
lightning grounded through the pool filter pump motor - blowing a hole in
the side of the coax

http://nj-bob.smugmug.com/Radio-Stuff/Lightning-Strike-052505/556399_qL6ML#2
3130433_v6ezB-A-LB

It toasted the filter pump motor, the freeze protector and also the pool
heater. All of it had to be replaced.

The antenna's matching network exploded and sent shards of plastic flying
all over the yard and in the pool.

More photos here:

http://nj-bob.smugmug.com/Radio-Stuff/Lightning-Strike-052505/556399_qL6ML#2
3130442_qkYFL

I wonder if I had the antenna grounded through some sort of protective
device that I might have avoided the resulting damage?

73,

Bob W5OV

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Tom W8JI
Sent: Friday, March 19, 2010 6:36 PM
To: Charles Teeter; [hidden email]
Subject: Re: [Elecraft] [OT] Grounding Antenna when not in use

After I get my kit built, I¹ll be operating with a windom
antenna on 40
10. It¹s been suggested that when I¹m not operating, I
should disconnect
the rig from the antenna and run the antenna to ground.
I¹ve never done
that in the past when I operated with wire antennas or my
vertical, but it
does make sense as a safety precaution. I¹m wondering if
anyone has any
suggestions about the best way(s) to do that? Are there any
pieces of
equipment that you would recommend to simplify the process?
Any help would
be greatly appreciated. Thanks.>>

Chuck,

Nearly all the time when there is serious damage, it comes
from a loop from power lines to your antenna and station
ground.

http://www.w8ji.com/ground_systems.htm

You either MUST have a proper station ground bonded to the
power mains ground and a bulkhead entrance, or you really
would have to take the rig totally out of line. No power
supply connections, computer connections, antenna, or
anything.

Although it is popular, grounding the antenna when off
really means next to nothing. It can help if a hit is a mile
away, or from p-static charging, but it won't do a thing if
lightning hits the mains (very common) or the antenna (very
rare unless you have a tall tower).

For automatic antenna disconnect and static shielding you
really need a double-make double-break relay, in a proper
box with proper layout, to totally isolate the center
conductor. It has to be a properly configured double-make
double-break that grounds the transfer bar when the relay is
off. Any other type of relay or switch is not secure at all.

Tom

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.hank.

Re: [OT] Grounding Antenna when not in use

In reply to this post by Chuck Teeter KE9CE

Chuck .....
Like you, I have never had to disconnect any radios in the past from the antenna - except during severe thunder storms.
About a year ago when the SWR SMT diodes went bad in my K3, I admitted to K3 support that I did not remove the coax from the back of the K3 but I grounded the Six Pak switch connections out in the garage. They were adamant that the diodes went bad because of something like "residual static build-up" and they would supply the replacement diodes, but not replace them under warranty.
I struggled with the replacement (I hate SMT, but that's my problem).
I now remove the K3's coax where it comes in the house before I leave the shack .... even though the rating of the original diodes was increased to (I think) 70VDC.
It's better to be safe than sorry!
73 Hank K8DD

Don Wilhelm-4

Re: [OT] Grounding Antenna when not in use

In reply to this post by Chuck Teeter KE9CE

Chuck,

Grounding the antenna is not as important as disconnecting the
transceiver from the feedline when no in use.
I have a relay switching arrangement for my shack which connects the
transceiver to a dummy load when no antenna is connected, and my remote
antenna relays connect unused antennas to ground (at that remote
location). I also have spark-gap surge protectors in the shack across
each feedline.

As Tom W8JI pointed out, this may not be adequate protection, but I
figure it helps, even if just a little bit.
I think Tom is referring to lightning damage to an installation, but I
believe my precautions help protect the receiver front end from nearby
lightning induced surges. I fully realize these measures are woefully
ineffective for a direct strike - I do have additional protection
against strong surges - all power, control circuits, telco and LAN
cabling in the hamshack come through a "grounding window" and I have
installed PolyPhaser protective devices at the place where all lines
enter the building, and I have an extensive grounding system. I still
do not trust it - when lightning is near, I stay away from the hamshack
area.

Do some study on the subject and take whatever measures toward the ideal
solution that are practical for you. I might add again here that *all*
ground rods must be tied to the utility ground rod with heavy wire.
That is protection for you and your equipment under elecrtical fault
conditions.

73,
Don W3FPR

Charles Teeter wrote:

W8JI

Re: [OT] Grounding Antenna when not in use

Do some study on the subject and take whatever measures
toward the ideal
solution that are practical for you. I might add again here
that *all*
ground rods must be tied to the utility ground rod with
heavy wire.
That is protection for you and your equipment under
elecrtical fault
conditions.
>>

That's good advice. It's a national electrical code
requirement that the station ground has to be tied to the
mains ground, not just for power line faults or equipment
faults but also for lightning.

Assuming we have a normal height antenna and above-ground
utilities, most hits that cause damage are on power lines.
The surge runs through the power lines to ground through our
gear if the equipment ground is not bonded to the mains
ground. The opposite is true also if the antenna gets hit.
Bonding the station ground to the mains ground diverts
current from that path through the house.

While disconnecting an antenna does help for close hits or
static buildup, the devil is in the fine details of how we
do things....not what we think we do.

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daleputnam

Re: [OT] Grounding Antenna when not in use

In reply to this post by Don Wilhelm-4

Ad Don points out very well, disconnect is best. Why? There are many white papers about that will dazzle you with there brilliance and take a lot of your time, how about I skin it for you?

Because: And electrical flow/current will follow Kirkov's law. agreed?

There fore, follow the flow of a direct hit, down the tower.. now the hit was to the tower. As the current flows down the tower, voltage is induced... into the feedline that is strapped to the tower. (that is the way transformers work, right?) So the current gets to the ground, but just before that.. it sees two paths.. the one to ground.. and the one along the feed line... or cable carrier (wire support or rack), so it flows both ways.

Lets follow the one along the feedline... It gets to a polyphasor... spark gap or choke,

good.. it "sees" two paths again... ok.. follow the one on in... and the path to ground may cause induction into? But the one in.. past the spark gap, goes on in.. and flows along ... how far? ... next to? ... towards an unprotected (now) rx amp or tr contact or.... but wait.. how much voltage is it now? How much damage can it really cause?

Consider what the breakdown voltage of that diode junction really is... then consider that the hit had... oh... say 100,000 volts.... and at each divider point it dropped 80 percent... you have two maybe three points?.... lets see.. the math.. oh no.. the math...

80% of 100k.. and 80% of ... and maybe 80% of....

guess what... I figure, that you may get close. may get close to saving that diode.

But... I also figure that my 80%... maybe 90... or it may be 70.... and I would really rather play radio, than play with numbers.... so

I disconnect... all the radios. and I have still heard the coax zapping, during a storm.

I'm thinking that is enough to cook a junction.

--... ...-- Dale - WC7S in Wy

>
> Grounding the antenna is not as important as disconnecting the
> transceiver from the feedline when no in use.

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Nick Kennedy

Re: [OT] Grounding Antenna when not in use

In reply to this post by .hank.

My antennas come in to one manual selector switch, which connects the
selected antenna to a second selector switch, which then connects that
to the desired rig. Both switches ground unselected inputs.

Since the K3 is switched to ANT1 when powered down, I keep my Cantenna
connected to the ANT1 input and I use ANT2, which connects to that
second selector switch. The K3 remembers that I like ANT2 when I power
up, so that's no hassle. If I "accidentally" transmit into ANT1,
there's a dummy load there. So I have some level of protection even if
I forget to rotate both switches to ground or unused inputs when not
operating. I usually do remember though, since I also lost my SWR /
power measuring diodes to a nearby lightning strike, so I've got several
levels of protection. I admit this isn't as good as disconnecting coax,
but I'd never get on the air if I had to go through all of that every
time I turned on the rig.

Some guys disconnect everything and throw it outside, seal the rig in
the original shipping carton, sacrifice a goat and pray a novena when
thunder approaches, but I can't go that far. I think my next logical
step would be to have the AC plug for my K3's power supply handy at
desktop level so I can easily pull it when I'm going to be away from the
rig for a while. This in response to what W8JI said about the mains
connection being the primary path for damage.

73-Nick, WA5BDU

.hank. wrote:
> Chuck .....
> Like you, I have never had to disconnect any radios in the past from the
> antenna - except during severe thunder storms.
> About a year ago when the SWR SMT diodes went bad in my K3, I admitted to K3
> support that I did not remove the coax from the back of the K3 but I
> grounded the Six Pak switch connections out in the garage.

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alorona

Re: [OT] Grounding Antenna when not in use

In reply to this post by Bob Naumann W5OV

Maybe I can throw this in here quickly while we're on the subject of lightning.

For a long time I have wanted to have a list of lightning strikes by county, but have never been able to find such a statistic on the web.

Has anyone ever run across this information? Please respond privately to reduce reflector traffic.

Al W6LX

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