Antenna static charge precautions - any tips?

[Vic Rosenthal]

Which reminds me: I have ICE lightning protectors on my feedlines where they come into the
shack. These have a built-in choke across the side that goes to the antenna, which drains
static charges. See
<http://www.arraysolutions.com/Products/surge_arrestorAS-3xx.htm>

The only disadvantage of these is that they also have a DC blocking capacitor in series
with the center conductor, which complicates things if you want to inject a DC voltage to
operate a remote switch or tuner.

On 9/9/2012 3:28 PM, Ron D'Eau Claire wrote:

> Keep in mind that the resistors (or a choke) only provide PARTIAL
> protection. If you connect an antenna to the rig that has accumulated a
> significant voltage - which can happen in a couple of minutes in dry windy
> conditions, in a rainfall, or even during a snowfall, you'll still damage
> the rig when you connect it because the voltage won't drop fast enough
> through the protection circuit. Not even a choke may protect against that
> due to the rapid rise time of the spike.
>
> That's why it's an excellent idea to keep any disconnected antennas grounded
> or, if one has been left open, to ground it before connecting it to the rig.
>
>
> Hopefully less common is a nearby lightening discharge that induces a
> current in the antenna. I'm not talking about a direct hit or even anything
> close to it. The strike may be some distance away and still induce a
> damaging amount of current that the resistor (or choke) cannot bleed off
> fast enough. That's another reason to shut down and ground antennas if
> lightning can be heard, no matter how far away.
>
> 73, Ron AC7AC

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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[Mel]

OK, the thread triggered me.  At my station on top of a flat top mesa with a 180 foot tower and EDZ antennas on 160 and full wave inverted V antennas that do not have an DC ground.  I do static discharge a little different.  I use open frame relays to do all of the ladder line switching of the individual  antennas.  But I include a short across the ladder line leads and a earth ground when that antenna is not is use.  That way when I switch in a new antenna, it is dead earth potential.  Just a thought. 
 
Mel, K6KBE

--- On Sun, 9/9/12, Vic K2VCO <[hidden email]> wrote:


From: Vic K2VCO <[hidden email]>
Subject: Re: [Elecraft] Antenna static charge precautions - any tips?
To: [hidden email]
Date: Sunday, September 9, 2012, 3:59 PM


Which reminds me: I have ICE lightning protectors on my feedlines where they come into the
shack. These have a built-in choke across the side that goes to the antenna, which drains
static charges. See
<http://www.arraysolutions.com/Products/surge_arrestorAS-3xx.htm>

The only disadvantage of these is that they also have a DC blocking capacitor in series
with the center conductor, which complicates things if you want to inject a DC voltage to
operate a remote switch or tuner.

On 9/9/2012 3:28 PM, Ron D'Eau Claire wrote:

> Keep in mind that the resistors (or a choke) only provide PARTIAL
> protection. If you connect an antenna to the rig that has accumulated a
> significant voltage - which can happen in a couple of minutes in dry windy
> conditions, in a rainfall, or even during a snowfall, you'll still damage
> the rig when you connect it because the voltage won't drop fast enough
> through the protection circuit. Not even a choke may protect against that
> due to the rapid rise time of the spike.
>
> That's why it's an excellent idea to keep any disconnected antennas grounded
> or, if one has been left open, to ground it before connecting it to the rig.
>
>
> Hopefully less common is a nearby lightening discharge that induces a
> current in the antenna. I'm not talking about a direct hit or even anything
> close to it. The strike may be some distance away and still induce a
> damaging amount of current that the resistor (or choke) cannot bleed off
> fast enough. That's another reason to shut down and ground antennas if
> lightning can be heard, no matter how far away.
>
> 73, Ron AC7AC

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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[Scott Monks]

Hi all;

>________________________________
> From: Bob Cunnings <[hidden email]>
>
>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
>I certainly am not an expert at this, but I have a question.

Recently I had to dismantle my antenna (brand name unnecessary) to take out a burned gas discharge tube.  I had been operating it on a Warc band for which it was not designed, made possible by the efficient tuner of my K3.  I was told that the tube might have/probably burned out because it was seeing a high SWR that, of course, was not actually corrected at the antenna (just in my radio, as expected).

Now, if that was what happened, what is there to keep the same thing from happening in my K3?  Obviously, there must be something!

73,
Scott   XE1/AA0AA; AA0AA
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[vk4tux]

Unusual to see that as an issue withought using an amplifier, however the high antenna feedpoint impedance on such setups produce a high voltage at that point, despite the atu proving a 50 ohm impedance match to the transceiver.

Baluns rated at 3-5 KW are so only at 1:1 swr. When swr raises to 5:1 on certail bands on a ocf setup then really you should derare the power rating by the denominator 5, such that a 5KW rating becomes 1KW.
This will provide a long life on ocf setups etc.








"Recently I had to dismantle my antenna (brand name unnecessary) to take out a burned gas discharge tube.  I had been operating it on a Warc band for which it was not designed, made possible by the efficient tuner of my K3.  I was told that the tube might have/probably burned out because it was seeing a high SWR that, of course, was not actually corrected at the antenna (just in my radio, as expected).

Now, if that was what happened, what is there to keep the same thing from happening in my K3?  Obviously, there must be something!

73,
Scott   XE1/AA0AA; AA0AA"

[Don Wilhelm-4]

Scott,

You will have to "do the math"  to figure out the actual voltage and
current of the components.  The formula is the standard I squared R
power losses, or the IR voltage or some other aspect of ohms law. Gas
discharge tubes will conduct when the peak voltage exceeds its rating.

If your antenna has components that will produce high voltages or high
currents, then those values must be taken into consideration.

I do not understand your concern for the K3.  The KAT3 was working to
produce a low SWR (and a 50 ohm load) for the K3, so that condition was
apparently satisfied.  The high voltage condition existed only at the
antenna which was not resonant at the frequency that it was used on.

73,
Don W3FPR

On 9/9/2012 7:32 PM, Scott Monks wrote:

> Hi all;
>
>
>
>
>> ________________________________
>> From: Bob Cunnings <[hidden email]>
>>
>> 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
>> I certainly am not an expert at this, but I have a question.
> Recently I had to dismantle my antenna (brand name unnecessary) to take out a burned gas discharge tube.  I had been operating it on a Warc band for which it was not designed, made possible by the efficient tuner of my K3.  I was told that the tube might have/probably burned out because it was seeing a high SWR that, of course, was not actually corrected at the antenna (just in my radio, as expected).
>
> Now, if that was what happened, what is there to keep the same thing from happening in my K3?  Obviously, there must be something!
>
> 73,
> Scott   XE1/AA0AA; AA0AA
> ______________________________________________________________
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[Scott Monks]

>________________________________
> From: Don Wilhelm <[hidden email]>
>
>I do not understand your concern for the K3.  The KAT3 was working to
>produce a low SWR (and a 50 ohm load) for the K3, so that condition was
>apparently satisfied.  The high voltage condition existed only at the
>antenna which was not resonant at the frequency that it was used on.
>Sometimes the ATU does not adjust the SWR to 1:1, or at least not until I manually push the button.  These times the SWR may be 3:1 or a little more--I don't know why it doesn't always adjust the SWR, but everything seems to be working ok in general, but may be that the antenna still is too low and sometimes interacts with the roof.  Why not always?  Don't know, I just observe!

My concern is because I was told by several, including the manufacturer of the antenna, that the discharge tube will burn out if it faces more than about 3:1 SWR.  The ATU, if you view it as a black box, has the radio side at 1:1 but the antenna side is at the higher SWR.  My concern is, if the gas tube in the radio is on the high SWR side it will actually be exposed to the higher SWR--will that also cause it to be burned out?

I could just becrazy (happens often!) but I don't want my radio to be damaged because of my stupidity!


73.
Scott
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[Scott Monks]

>________________________________
> Unusual to see that as an issue without using an amplifier, however the
>high antenna feedpoint impedance on such setups produce a high voltage at
>that point, despite the atu proving a 50 ohm impedance match to the
>transceiver.
>
I agree, and since I am only using 100 watts, didn't expect to have problems with the gas tube since even the manual mentioned only that this might occur at high power.  I live in a windy area, sometimes with blowing dust sometimes with electric discharge, so it might be that was burned by one of these events and not the SWR.

My main concern is the radio--if using the antenna out-of-band with the ATU does not put the radio at risk (I think not but am not an expert!) then I will not worry!

73,
Scott
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[Richard Fjeld]

Good demo.  To that cause, I'd like to share a true experience that happened
to me as part of a group of Explorer Scouts on Field Day one year.  I was an
advisor, and had installed a ground rod, and connected a coax switch to it
so that we could ground our antennas if weather threatened. The switch was
inside a shelter.

The sky above us was clear blue and sunny.  Off to the west were black
clouds and lightning that was moving our way.  I told the scouts to connect
the antenna coax plugs to the coax switch.  As we attempted to connect the
first one from a dipole, we drew a steady blue arc to the shell of the
switch. It was quite a gap, too.  It was blue sky and sunny in our half of
the sky. Yet, the static build up from the storm caused enough voltage to
arc that much.  That was hard to believe.

As a footnote, I made the mistake of holding the coax switch with one hand,
while holding the PL259 with the other hand.  It was like touching the tip
of a spark plug.

----- Original Message -----
From: "stan levandowski" <[hidden email]>
Cc: <[hidden email]>
Sent: Sunday, September 09, 2012 9:04 AM
Subject: Re: [Elecraft] Antenna static charge precautions - any tips?

> 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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[Geoffrey Mackenzie-Kennedy-3]

Mike,

A point worth mentioning I believe, is that a static drain resistor placed
inside a transceiver/ transmitter/ receiver as you suggest will provide some
protection against static should an external static drain resistor fail into
an open condition.  Certainly good practice IMHO.

73,

Geoff
LX2AO


On September 09, 2012 at 10:31 PM, Mike Morrow wrote:


 > 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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