Static discharge control from open wire line antennas?

[ke7trp]

The past few weeks I have not been able to talk on the radio much due to static building up on my Wire antenna. This antenna is 60 ft up horizontal fed with 600 ohm open wire line.  This line feeds to the Johnson KW matchbox.  It then can feed my 4 stations.

I get a spark from each leg of the open wire line from the insulator on the back of the tuner to the case or to the Ground lug. These arcs are up to 3 inches long!  It is very loud and if you are at the far end of the house you can hear it CRACK CRACK CRACK!

The solution I use is to attach jump leads from ground to the antenna lugs using a long insulated plier. Once its grounded, this stops.  Obviously, I unhook my radios when this happens.

The problem is that this happens nearly all day long and most of the night. So far, I thas not destroyed any of my radios. Although, I am worried about using my 1000D. 

Even if the spark is not jumping in the room, The Reciever gets blanked out for a second through my QSOs. 

It has been suggested to me that I should build some Transmitting chokes.  I am going to look through my handbooks to see if I can find some designs. 

Has anyone built a choke or does anyone have a solution? 

Clark

[Steve - WB3HUZ]

Try grounding the center of the coil in the matchbox.

[ke7trp]

Which coil?  I guess you mean the large one? I have seen this on other home brew tuners.

Clark

[WA1GFZ]

Yes this will bleed off the static.

[WA1GFZ]

Be careful with the matchbox since the CT shifts on the higher bands. I think only 1 additional turn is shorted going from 15 to 10 meters.

[ke7trp]

So I need to Center tap this large coil?  Thats going to be difficult.. The turns are shorted as the band changes like you suggested.  Where should I ground it?

[WA1GFZ]

I think the CT only shifts on 15 or 10 meters the lower bands will have the CT in the same spot since the shorted turns are equal on 40 and 20 each side of ct. which is the same as 80m.  Also you could put small spark gaps on the feed line just wide enough to not spart while in TX. Might only need .1 to .25 inch gap.

[ke7trp]

Any drawbacks to doing this?  I have a spare KW matchbox. I can take it apart and test this in realtime with a Clip lead to see if it helps. I had to get off 40 meters a few minutes ago as it was starting to spark.

Clark

[kc2ifr]

An rf choke from each feeder to ground will do the trick also.

[ke7trp]

This is what the guys suggested on 40..  Where do I get some and what kind? How do they hook up?

C

[W9GT]

The RF chokes should just be some heavy xmtg type units..value not critical, just a few millihenries...use identical chokes for each side. 

Are you near a high tension power line?  I hope you aren't seeing some induced energy on your antenna from a power line.  Seems like that static build-up is rather severe.  Chokes should fix it though.

73,  Jack, W9GT

[kc2ifr]

I think about 40 to 50 uH will do it. Connect 1 to each feed line just before the feeders enter the house and then connect them to a GOOD GROUND.......a 10 foot ground rod should do it.

[ke7trp]

All the lines are underground here.  I think its the weather.  This happens every year and sometimes through the year.

My vertical has been up on the tower for years. It will throw 1 foot!  Arcs out the top to the atmosphere like a bull whip about 3 or 4 times a year. This takes out the cable modem (I have been through 8 of them now!), the digital cable box reboots and phones stop working..

You really cant use anything electronic during this time. I have had people next door come over and knock on my door as they hear this LOUD Cracking sound and they can see the big arcs.  It also arcs from the attachment point of each section of the antenna.  It killed a few radios over the years.  MOST of the time this is never an issue..  But certain times of the year right BEFORE the storms hit, I get the big arcs.  Most of the time its static crashes and or minor sparking at the back of the tuner.

I have mentioned this over the years and have had little help. A few radio friends of mine have been over then this happens and there eyes look like silver dollars when they see those arcs!  LOL.  I am used to it..  My main quest is just to stop this Noise and crashes on my Reciever so I can use the radios!

I need to find a source or make some chokes.. Any more information would be great!

I am sure there are alot of people that have had this issue and I am sure there are alot of solutions!

[ke7trp]

Will any of these from RF parts work?

http://www.rfparts.com/choke.html

[kc2ifr]

With my kw matchbox......the arcing happens from the unused pl259. It arcs from the center conductor of the jack to the threaded outside of the connector.

Bill

[Mike/W8BAC]

Hi Clark,
This link will take you to Array Solutions and his static/surge coils. I use them and they will end your static problem. Tie one to each feeder and ground the other end.

http://www.arraysolutions.com/Products/staticsurgecoils.htm

[w3jn]

Collins did it with high voltage resistors (couple megs or so) in the 180L auto tuners.

[ke7trp]

Thats the answer.. $70 and an hour of time and I can have those coils installed on the outside of the house. I bet that solves my issues. Then, I can get a Coax style one for the big vertical.

Clark

[kc2ifr]

Just a quick comment......
These chokes are NOT meant to be lightning arrestors (the spell check on this board sucks!) The values of the chokes I sent u was considering the antenna was going to be used on 160. If the antenna is NOT going to used on 160, then the value of the chokes can be reduced to about 20uH.....

Bill

[KD6VXI]

The past few weeks I have not been able to talk on the radio much due to static building up on my Wire antenna. This antenna is 60 ft up horizontal fed with 600 ohm open wire line.  This line feeds to the Johnson KW matchbox.  It then can feed my 4 stations.

I get a spark from each leg of the open wire line from the insulator on the back of the tuner to the case or to the Ground lug. These arcs are up to 3 inches long!  It is very loud and if you are at the far end of the house you can hear it CRACK CRACK CRACK!

The solution I use is to attach jump leads from ground to the antenna lugs using a long insulated plier. Once its grounded, this stops.  Obviously, I unhook my radios when this happens.

The problem is that this happens nearly all day long and most of the night. So far, I thas not destroyed any of my radios. Although, I am worried about using my 1000D. 

Even if the spark is not jumping in the room, The Reciever gets blanked out for a second through my QSOs. 

It has been suggested to me that I should build some Transmitting chokes.  I am going to look through my handbooks to see if I can find some designs. 

Has anyone built a choke or does anyone have a solution? 

Clark

I'vbe witnessed what Clark is talking about, at his QTH about 2 years ago.  On a 10 meter 'stick' style antenna, it turns into QUITE the tesla.

If you look at the schematic of MOST upper end CB radios, you will find a choke that goes from the SO239 center pin to the ground lug.  This is to bleed off EXACTLY what you are seeing.  Older radios used a resistor, but as anyone who has an SB220 can tell you, lots of overvoltage over the years can cause them resistors to change values, and sometimes a LOT.

If you want to test it, and can find them, grab a couple 5 dollar Cobra 20 series radios from the local swap meet.  Remove the choke from the SO239 connector on the back, and do one to ground from each side of your feedline, or as others have said, center tap the Johnson.  Any old carcasses of 10 meter amps usually have them as well...  More a solid state radio thing, and for some reason, a tubed amplifier thing.....  The solid state amps I've seen lately don't have them.  Guess they count on the radio having it installed.

Also, on a related subject...  A local truck driver friend went through 3 Galaxy radios in his truck...  The newer MOSFET style output ones.  As SOON as he got rid of the Wilson Silver Load (fiberglass) and went to a stainless style antenna, no more blown MOSFETS.  I had to send the company a pic of the MFJ screen...  They couldn't believe it was happening and the installation was good.

Now, they ask people who return their radios what type of antennas they have...  Fiberglass or covered, and they tell them to go to a 'metal' antenna.

Your antennas are all covered, huh?  And them DAMN desert winds blowing across all that insulation causes problems, huh?  Like, static buildup.

Same thing I told you years ago, when I saw it on your fiberglass antenna at the time.

Kill the insulation, and I bet your problem goes away.  If the antenna and feeders, etc. are ALL bare copper, I'm at a loss.

--Shane

[K9ACT]

Just a quick comment......
These chokes are NOT meant to be lightning arrestors (the spell check on this board sucks!) The values of the chokes I sent u was considering the antenna was going to be used on 160.

50 uH would be about 2 inches of #18 wire on a 1.5" pvc pipe.  Or 48 turns and 6 yards of wire.

I don't begrudge some entrepreneur making a buck but this really seams like a nice and simple homebrew project.

No one has mentioned those gas discharge gizzmos MFJ sells.  They are intended for coax but you could use two for a balanced line.  I believe one the hookers is that they have a limited life time and get used up.

This whole issue of 3" sparks boggles my brain and I am sure glad I don't have this problem.

However, I do have similar thoughts on the spell checker on this list and was actually going to post a thread on the issue because my complaints go unremarked.

As far as I can tell, all it does it red line an incorrectly spelled word and offer no help correcting it.

My wife and I spent about 10 minutes working out the spelling of categorically for a previous posting .  Couldn't even find it in the dictionary until we tried changing an a to an e.  This spell checker just produces a guessing game.

js

[K9ACT]

If you look at the schematic of MOST upper end CB radios, you will find a choke that goes from the SO239 center pin to the ground lug.  This is to bleed off EXACTLY what you are seeing. it installed.

I don't think that is the point of that choke and it certainly offers no help in the receive mode which is where the antenna spends most of its time.

That choke is used in pi output tank circuits to limit the voltage on the loading cap and as a safety measure to blow a fuse if the blocking cap should short out and try to put high voltage on the antenna system.  All pi net output transmitters should have this choke for both reasons.

js

[ke7trp]

I guess I could make my own.  I will look into it. 

My Wire is bare. No insulation. The Feeder does have insulation on it though.  I have this problem on my Vertical, and on the Zep antenna. I dont have this problem on the 160M L antenna that is coax fed, grounded to the tower and uses bare wire.

I dont think those small chokes will take the 1500 watts I put through this antenna.

Clark

[n2bc]

A 1mH choke on 160M looks like a 12K resistor...  Why not just stick a 50K resistor from each side of the feedline to ground - no more static buildup.

[WA1GFZ]

as long as the resistor can handle the flash over voltage of the tuner 7000 v.