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Antenna static charge precautions - any tips?

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VK7JB

Antenna static charge precautions - any tips?

Hello Group,

I've just re-hung my 80m horizontal loop. With so much wire in the
air, I'm reviewing my static charge risks and how to reduce them to
protect my K3. I'm in the mountains - things get bumpy and charged
up here. I once lost the wattmeter diodes in my K2/100 to a static
event, so I'm looking for prevention. Any advice will be gratefully
received.

Here's my new setup:

80m loop fed with open wire line to a DX Engineering 1:1 balun outside
the shack. A 5 foot length of RG213 brings the signal from the
balun, through the shack wall to an AlphaDelta antenna switch. The
outer shield of the RG213 is connected to the station ground, at the
balun, outside the shack. The AlphaDelta switch is connected also to
the same station ground. It grounds the centre conductor of all
antenna lines when in the "common" position - and I leave it this
way whenever I'm not operating. My understanding is that any antenna
lines are protected by a gas discharge capsule in this switch, which
acts as a "fuse" in the event of significant static discharge on an
ungrounded line?

"Station ground" here means 2 copper pipes buried in earth outside the
shack and connected by about 6 feet of cable. One of the pipes is in
very damp earth most of the year, the other is sheltered and is in dry
soil.

Is this setup sufficient to manage static discharge risk from my
antenna, or are there other precautions I should be taking? I've
read about ICE static discharge devices and high value resistors
from both sides of the ladder line to ground. Just looking to
minimise risk without going overboard.

Thanks and 73
John
VK7JB

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Don Wilhelm-4

Re: Antenna static charge precautions - any tips?

John,

Put a resistor across each feedline is my advice. A value from 22k (I
like 3 watts for legal limit rating) to 100k will discharge the static.
A DC path across the feedline is a very good protection against antenna
static damage to your rig - the path to ground is not as essential as
across the feedline, but a path to ground does add benefit as well.

You can add resistors at the feedpoint of your antennas - that gives an
added benefit of being able to check for breaks in the feedline, just
measure the resistance across the feedline. That does not work for
loops since the closed loop should indicate a resistance that is quite
low itself.

If you care to open the Alpha Delta switch, that is a great place to
install them - if you have no other choice, put the resistors in a
PL-259 body, one lead to the center conductor and solder the other lead
to the shell - then use a Tee adapter to connect the resistor across the
feedline.

The Gas discharge tubes are effective against large charges - the ones I
have will squelch a voltage in excess of 600 volts, but below that
level, they will do nothing. That 600 volt surge is enough to take out
the diodes in the K2 KPA100. The K3 has more protection. but still
should not be trusted when it comes to static charges.

The simple resistor across each feedline will bleed off static and help
substantially. An alternative to the resistor is a choke (of adequate
current capacity for the power of your station). In a 50 ohm system,
100 uHy or greater will be good down to 160 meters.

73,
Don W3FPR

On 9/8/2012 8:25 PM, [hidden email] wrote:

> Hello Group,
>
> I've just re-hung my 80m horizontal loop. With so much wire in the
> air, I'm reviewing my static charge risks and how to reduce them to
> protect my K3. I'm in the mountains - things get bumpy and charged
> up here. I once lost the wattmeter diodes in my K2/100 to a static
> event, so I'm looking for prevention. Any advice will be gratefully
> received.
>
> Here's my new setup:
>
> 80m loop fed with open wire line to a DX Engineering 1:1 balun outside
> the shack. A 5 foot length of RG213 brings the signal from the
> balun, through the shack wall to an AlphaDelta antenna switch. The
> outer shield of the RG213 is connected to the station ground, at the
> balun, outside the shack. The AlphaDelta switch is connected also to
> the same station ground. It grounds the centre conductor of all
> antenna lines when in the "common" position - and I leave it this
> way whenever I'm not operating. My understanding is that any antenna
> lines are protected by a gas discharge capsule in this switch, which
> acts as a "fuse" in the event of significant static discharge on an
> ungrounded line?
>
> "Station ground" here means 2 copper pipes buried in earth outside the
> shack and connected by about 6 feet of cable. One of the pipes is in
> very damp earth most of the year, the other is sheltered and is in dry
> soil.
>
> Is this setup sufficient to manage static discharge risk from my
> antenna, or are there other precautions I should be taking? I've
> read about ICE static discharge devices and high value resistors
> from both sides of the ladder line to ground. Just looking to
> minimise risk without going overboard.
>
>

stan levandowski

Re: Antenna static charge precautions - any tips?

In reply to this post by VK7JB

Thanks, Don. I have a homebrew doublet with a gas discharge center
insulator and I have been under the (apparently incorrect) assumption
that I've been well protected from static buildup. I've also got a
coaxial switch which is dialed into the dummy load when not in use.

Guess, I better go out and buy a 22K resistor now and fnish the job ;)

Appreciate the tip.

73, Stan WB2LQF

On Sat, Sep 8, 2012 at 9:17 PM, Don Wilhelm wrote:

>
> The Gas discharge tubes are effective against large charges - the ones
> I have will squelch a voltage in excess of 600 volts, but below that
> level, they will do nothing. That 600 volt surge is enough to take
> out the diodes in the K2 KPA100. The K3 has more protection. but
> still should not be trusted when it comes to static charges.
>
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Hank Garretson

Re: Antenna static charge precautions - any tips?

On Sat, Sep 8, 2012 at 7:07 PM, stan levandowski <[hidden email]>wrote:

Guess, I better go out and buy a 22K resistor now and fnish the job ;)
>

I use a 3 megohm resistor. Since the purpose is to bleed off static
buildup, high resistance is fine. Depending on your antenna, frequency,
feeder impedance, and feeder length, who knows what the impedance is at the
shack. It could be above 2000 ohms in which case ten percent of your power
would be dissipated in the resistor. Go high resistance and you won't have
to worry.

Ski Exuberantly,

Hank, W6SX

Mammoth Lakes, California

Elevation 8083 feet in John Muir's Range of Light
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Don Wilhelm-5

Re: Antenna static charge precautions - any tips?

In reply to this post by stan levandowski

OK a bit of explanation is in order. The K2 (and K3 as well as the K1)
control power based on measuring the actual output power and adjusting
the drive to provide the requested power level. That means a device
capable of measuring the RF output is necessary.
Well, that is the wattmeter in the KPA100 - it uses Schotky 1N5711
diodes because those have been chosen to provide the best response with
respect to frequency and power level.

Yes, those diodes are a bit "tender" with respect to static. Those
diodes live right at the antenna terminals and are quite susceptible to
static charges. The K2 (K3) power control system will give you the most
consistent power control (because it is a closed loop), but to operate,
it must be able to measure the output power. and the diodes that do that
task are susceptible to static discharges.

Yes, go out and find yourself some resistors between 22k and 100k and
connect them across your feedlines.

Note that I do not care about the path to (earth) ground - while that
may be nice, IMHO it will not help with the equipment damage from
antenna induced static charges. Yes, the station should be connected to
earth ground, but for purposes of lightning protection rather than
static discharges from antennas.

There are 3 grounds in a ham station - AC safety ground (see NEC
requirements), Lightning safety grounding (see Ron Block's papers at
Polyphaser,.com) and RF ground. The RF ground is the most elusive,
because it does not include any hard connection to mother earth.
"Ground" in this sense is a point of commonality, or a point where the
RF voltage is zero. That condition occurs at the feedpoint of a
balanced antenna - the zero voltage point directly between the feedpoint
terminals.

OK, I am mixing a bit of the theoretical and the practical, but take to
heart, it is not hard. When the wavefront moves from the feedline into
the antenna, the conditions change from conduction (obeying Kirchoff's
laws) to radiation (obeying Maxwell's wave equations). Where the
transition point occurs is indeed a mystery.

That has nothing to do with the "ground question".. Everything needs to
have a return path, and I believe that is valid for RF as well as for DC
conditions. This is the Kirchoff stance,, but there are those who argue
than the Maxwellian equations offer a better explanation. That may be
true, but there is little difference.

My goal is not to "solve" this inconsistency, but just to add a bit more
information (OK, to justify my conclusions be they right or wrong).

73,
Don W3FPR

On 9/8/2012 10:07 PM, stan levandowski wrote:

> Thanks, Don. I have a homebrew doublet with a gas discharge center
> insulator and I have been under the (apparently incorrect) assumption
> that I've been well protected from static buildup. I've also got a
> coaxial switch which is dialed into the dummy load when not in use.
>
> Guess, I better go out and buy a 22K resistor now and fnish the job ;)
>
> Appreciate the tip.
>
> 73, Stan WB2LQF
>
>
> On Sat, Sep 8, 2012 at 9:17 PM, Don Wilhelm wrote:
>
>
>>
>> The Gas discharge tubes are effective against large charges - the
>> ones I have will squelch a voltage in excess of 600 volts, but below
>> that level, they will do nothing. That 600 volt surge is enough to
>> take out the diodes in the K2 KPA100. The K3 has more protection.
>> but still should not be trusted when it comes to static charges.
>>
>

k6dgw

Re: Antenna static charge precautions - any tips?

Don is totally right. But, cutting to the chase, put a 100K resistor
across your coax before it gets to the receiver. Easy, no RX mods, just
put a 100K resistor ... 1/2W will do fine ... into a PL259. Put a UHF
T-connector on your radio, put the antenna on one leg, put your
resistive PL259 on the other.

Trust me, you *CAN* fry the input stages to your radio and it won't even
look like you're doing it as you are. Been there -- done that, more
than once, we all learn slowly. :-) No bleed = charge builds up in the
input capacitance, it will eventually take something out.

73,

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

On 9/8/2012 8:03 PM, Don Wilhelm wrote:

> OK a bit of explanation is in order. The K2 (and K3 as well as the K1)
> control power based on measuring the actual output power and adjusting
> the drive to provide the requested power level. That means a device
> capable of measuring the RF output is necessary.
> Well, that is the wattmeter in the KPA100 - it uses Schotky 1N5711
> diodes because those have been chosen to provide the best response with
> respect to frequency and power level.
>
> Yes, those diodes are a bit "tender" with respect to static. Those
> diodes live right at the antenna terminals and are quite susceptible to
> static charges. The K2 (K3) power control system will give you the most
> consistent power control (because it is a closed loop), but to operate,
> it must be able to measure the output power. and the diodes that do that
> task are susceptible to static discharges.
>
> Yes, go out and find yourself some resistors between 22k and 100k and
> connect them across your feedlines.
>
> Note that I do not care about the path to (earth) ground - while that
> may be nice, IMHO it will not help with the equipment damage from
> antenna induced static charges. Yes, the station should be connected to
> earth ground, but for purposes of lightning protection rather than
> static discharges from antennas.
>
> There are 3 grounds in a ham station - AC safety ground (see NEC
> requirements), Lightning safety grounding (see Ron Block's papers at
> Polyphaser,.com) and RF ground. The RF ground is the most elusive,
> because it does not include any hard connection to mother earth.
> "Ground" in this sense is a point of commonality, or a point where the
> RF voltage is zero. That condition occurs at the feedpoint of a
> balanced antenna - the zero voltage point directly between the feedpoint
> terminals.
>
> OK, I am mixing a bit of the theoretical and the practical, but take to
> heart, it is not hard. When the wavefront moves from the feedline into
> the antenna, the conditions change from conduction (obeying Kirchoff's
> laws) to radiation (obeying Maxwell's wave equations). Where the
> transition point occurs is indeed a mystery.
>
> That has nothing to do with the "ground question".. Everything needs to
> have a return path, and I believe that is valid for RF as well as for DC
> conditions. This is the Kirchoff stance,, but there are those who argue
> than the Maxwellian equations offer a better explanation. That may be
> true, but there is little difference.
>
> My goal is not to "solve" this inconsistency, but just to add a bit more
> information (OK, to justify my conclusions be they right or wrong).
>
> 73,
> Don W3FPR
>
> On 9/8/2012 10:07 PM, stan levandowski wrote:
>> Thanks, Don. I have a homebrew doublet with a gas discharge center
>> insulator and I have been under the (apparently incorrect) assumption
>> that I've been well protected from static buildup. I've also got a
>> coaxial switch which is dialed into the dummy load when not in use.
>>
>> Guess, I better go out and buy a 22K resistor now and fnish the job ;)
>>
>> Appreciate the tip.
>>
>> 73, Stan WB2LQF
>>
>>
>> On Sat, Sep 8, 2012 at 9:17 PM, Don Wilhelm wrote:
>>
>>
>>>
>>> The Gas discharge tubes are effective against large charges - the
>>> ones I have will squelch a voltage in excess of 600 volts, but below
>>> that level, they will do nothing. That 600 volt surge is enough to
>>> take out the diodes in the K2 KPA100. The K3 has more protection.
>>> but still should not be trusted when it comes to static charges.
>>>
>>
>
> ______________________________________________________________
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>
>
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>

Chuck N4XS

Re: Antenna static charge precautions - any tips?

> -----Original Message-----
> From: [hidden email]
> Subject: [Elecraft] Antenna static charge precautions - any tips?
>
> ...I've just re-hung my 80m horizontal loop. With so much wire in the
> air, I'm reviewing my static charge risks and how to reduce them...

It looks to me like a loop antenna would not need a resistor to bleed static
charge. The center conductor is already connected to the shield by the
antenna wire itself. Am I missing something?

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ke9uw

Re: Antenna static charge precautions - any tips?

In reply to this post by k6dgw

Which begs the question...why isn't a 100K across the antenna jack in the original design?
BTW, I use a choke across the antenna leads.

Chuck, KE9UW
aka Jack, BMW Motorcycles BMWMOA #224

________________________________________
From: [hidden email] [[hidden email]] on behalf of Fred Jensen [[hidden email]]
Sent: Saturday, September 08, 2012 10:16 PM
To: [hidden email]
Subject: Re: [Elecraft] Antenna static charge precautions - any tips?

Don is totally right. But, cutting to the chase, put a 100K resistor
across your coax before it gets to the receiver. Easy, no RX mods, just
put a 100K resistor ... 1/2W will do fine ... into a PL259. Put a UHF
T-connector on your radio, put the antenna on one leg, put your
resistive PL259 on the other.

Trust me, you *CAN* fry the input stages to your radio and it won't even
look like you're doing it as you are. Been there -- done that, more
than once, we all learn slowly. :-) No bleed = charge builds up in the
input capacitance, it will eventually take something out.

73,

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

On 9/8/2012 8:03 PM, Don Wilhelm wrote:

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Chuck, KE9UW

stan levandowski

Re: Antenna static charge precautions - any tips?

In reply to this post by VK7JB

Short but interesting demo of antenna static discharge - good motivation
- http://www.youtube.com/watch?v=hlSpZ-ffacA - (BTW, I've heard the
FT-817 has a 22K resistor installed but don't know that for sure)
On Sun, Sep 9, 2012 at 9:28 AM, hawley, charles j jr wrote:

> Which begs the question...why isn't a 100K across the antenna jack in
> the original design?
> BTW, I use a choke across the antenna leads.
>
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ke9uw

Re: Antenna static charge precautions - any tips?

In reply to this post by ke9uw

I'll keep an eye on it :)

Sent from my iPhone

On Sep 9, 2012, at 10:53 AM, "Ron D'Eau Claire" <[hidden email]> wrote:

> Many antenna systems do not require this protection. They are shunt fed
> which provides a direct-current short across the feed line at all times.
>
> Chokes may work fine, but all chokes have some parasitic capacitance across
> the windings which means they have a series resonances somewhere across the
> RF spectrum. At those points the choke will greatly disturb the impedance
> presented to the rig and absorb RF, even to the point of catching fire!
>
> 73, Ron AC7AC
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of hawley, charles j jr
> Sent: Sunday, September 09, 2012 6:29 AM
> To: [hidden email]; [hidden email]
> Subject: Re: [Elecraft] Antenna static charge precautions - any tips?
>
> Which begs the question...why isn't a 100K across the antenna jack in the
> original design?
> BTW, I use a choke across the antenna leads.
>
> Chuck, KE9UW
> aka Jack, BMW Motorcycles BMWMOA #224
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Chuck, KE9UW

Mike Morrow-3

Re: Antenna static charge precautions - any tips?

In reply to this post by VK7JB

Ron wrote:

> Many antenna systems do not require this protection. They are shunt fed
> which provides a direct-current short across the feed line at all times.
>
> Chokes may work fine, but all chokes have some parasitic capacitance across
> the windings which means they have a series resonances somewhere across the
> RF spectrum.

Even in the "dark ages", most US WWII military aircraft HF receivers like the
famous BC-348-series were modified to install a 1 Mohm resistor from antenna
terminal to ground to dissipate antenna static. Static voltage build-up
on wire antennas external to the aircraft in motion could otherwise build up
quite high. The other approach was using a small neon bulb (NE-2) in place
of the resistor.

Compared to choke or neon bulb, the resistor seems to be the most elegant
solution in terms of simplicity with no detectable adverse consequences.

Chuck wrote:

> Which begs the question...why isn't a 100K across the antenna jack in the
> original design?

Good question...with no known good answer. :-)

73,
Mike / KK5F

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Bob Cunnings NW8L

Re: Antenna static charge precautions - any tips?

In reply to this post by VK7JB

Check the K3 schematics - there *is* a static bleed resistor at each
antenna input, including the KXV3 Rx Ant In jack.

Gas discharge tubes are also present in the KANT3, KAT3 and KRX3.

Bob NW8L

>Which begs the question...why isn't a 100K across the antenna jack in the
>original design?
>BTW, I use a choke across the antenna leads.
>
>Chuck, KE9UW
>aka Jack, BMW Motorcycles BMWMOA #224
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Mike Morrow-3

Re: Antenna static charge precautions - any tips?

In reply to this post by VK7JB

Bob wrote:

> Check the K3 schematics - there *is* a static bleed resistor at each
> antenna input, including the KXV3 Rx Ant In jack.

What about the KX3? There are no published schematics yet, AFAIK.

73,
Mike / KK5F
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Don Wilhelm-4

Re: Antenna static charge precautions - any tips?

Why be concerned about whether or not each and every transceiver adds a
static bleed resistor across the antenna, just bite the bullet and add
one to each feedline coming into the shack and forget the
"tooth-mashing" that comes about wondering where it should be done. I
for one feel that it is best done at the antenna feedline rather than
relying on the transceiver - that way I can connect the antennas to any
transceiver with no problem.
If you do not have a convenient access point to your feedline center
conductor, enter the TEE adapter. solder the resistor into a PL-259
body, and plug it into one side of the TEE adapter - leave it there for
all eternity.

73,
Don W3FPR

On 9/9/2012 2:39 PM, Mike Morrow wrote:

> Bob wrote:
>
>> Check the K3 schematics - there *is* a static bleed resistor at each
>> antenna input, including the KXV3 Rx Ant In jack.
> What about the KX3? There are no published schematics yet, AFAIK.
>
> 73,
> Mike / KK5F
> ______________________________________________________________
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Phillip Lontz

Re: Antenna static charge precautions - any tips?

In reply to this post by Bob Cunnings NW8L

So, the 22k - 100k carbon resistor is not needed and therefore would be redundant?

Phil
Santa Fe

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Mike Morrow-3

Re: Antenna static charge precautions - any tips?

In reply to this post by VK7JB

> Why be concerned about whether or not each and every transceiver adds a
> static bleed resistor across the antenna...

Well...perhaps because the addition of an internal high-ohm static bleed
resistor at *any* radio set's antenna connection is trivial yet very good
engineering practice that has no identifiable adverse effects and that
costs essentially nothing.

That's an 'all-win/no-lose' situation to this electrical engineer's eyes. :-)

YMMV

Mike / KK5F

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Bruce Beford-2

Re: Antenna static charge precautions - any tips?

In reply to this post by VK7JB

What Don was trying to express was that if you simply add a resistor to your
own antenna, you don't need to worry/wonder about whether or not it is
included in a particular transceiver.

It may be good engineering practice to add it to a transceiver one is
designing. However, if you do it yourself on your own antenna(s), you don't
need to know or care if was included in the rig by the designer. Of course,
it would be good to insure it is in (or added to) all your own radios, so
that you can connect them to any antenna with some confidence.

73,
Bruce, N1RX

> Why be concerned about whether or not each and every transceiver adds a
> static bleed resistor across the antenna...

Well...perhaps because the addition of an internal high-ohm static bleed
resistor at *any* radio set's antenna connection is trivial yet very good
engineering practice that has no identifiable adverse effects and that
costs essentially nothing.

That's an 'all-win/no-lose' situation to this electrical engineer's eyes.
:-)

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Don Wilhelm-4

Re: Antenna static charge precautions - any tips?

In reply to this post by Phillip Lontz

Phil,

That would be true only under certain conditions
What conditions are you referring to? Your post was void of any conditions.

73,
Don W3FPR
On 9/9/2012 4:02 PM, Phil Townsend wrote:

> So, the 22k - 100k carbon resistor is not needed and therefore would be redundant?
>
> Phil
> Santa Fe
>
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Phillip Lontz

Re: Antenna static charge precautions - any tips?

I was glad to see my K3 had the 560k resistors in place.
I checked the KX1 and don't see any installed...
Sooo... looks like its a good idea to place them somewhere in the feedline after the antenna switcher...or maybe within the the antenna switcher box.
Really glad this subject came up cause New Mexico has fabulously low humidity!
Anyway I have my PL 259 loaded with a nice Allen Brady 100k 2w resistor ready to play.

Phil
Santa Fe

On Sep 9, 2012, at 2:42 PM, Don Wilhelm <[hidden email]> wrot

Phil,

That would be true only under certain conditions
What conditions are you referring to? Your post was void of any conditions.

73,
Don W3FPR
On 9/9/2012 4:02 PM, Phil Townsend wrote:

Bill Frantz

Re: Antenna static charge precautions - any tips?

It seems to me that with an antenna switch that doesn't short
the unselected antennas by default, like the DX Engineering
RR8A-HP remote antenna switch, it might be advisable to either
set the switch up to short the unselected antennas or add a
resistor across them individually. Otherwise when an antenna
carrying a significant static charge is switched to a radio, the
charge might overwhelming the radio's protective resistors.

Whether dammage would occur depends on the inductance between
the antenna and the radio's sensitive components. The natural
inductance of the feed line wiring will broaden the electrical
pulse and give the radio's resistors more time to bleed off the
charge. I have no idea if typical feed lines have enough
inductance to protect a radio in these circumstances.

Cheers - Bill, AE6JV

On 9/9/12 at 14:19, [hidden email] (Phil Townsend) wrote:

>Sooo... looks like its a good idea to place them somewhere in
>the feedline after the antenna switcher...or maybe within the
>the antenna switcher box.
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