Static discharge control from open wire line antennas?

[ke7trp]

Option 1.  Install 50K resistors from feedline to ground (what wattage?)

Option 2. Ground the coil in the KW matchbox. (may lose 10/15)

Option 3.  Buy Transmitting coils and install them outside.

Option 4.  Wind my own Coils.


??

CLark

[WA1GFZ]

1. A 2 watt resistor is good for about 300 volts so series a bunch of them
4. find a nice pair of coil forma you will quickly find out if they resonate. Aviod PVC it gets lossy on higher bands. Fibergalss and teflon insulated wire should work fine #22. It does not need to be a round form. You could form a triangle or X with strips of PC board material without copper.
3 will work as long as they don't series resonate Not sure about the insulator material and outside wx.
2. I'm pretty sure the CT will be offset on 10 because onlt 1 additoinal turn of the big coil is shorted. It needs to be an even number for CT to be in the same place.

[KD6VXI]

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

No, that choke is there exactly for the function I mentioned.

It is mentioned in the ARRL Manual, and Orr's books, in the RX parts.

It's the same thing as the blocking choke, and on my old trusty cobra 148 in the truck, it is there.  Factory.

But, we are only arguing apples to persimmons, as we both know exactly what we are talking about

--Shane

[KD6VXI]

Option 1.  Install 50K resistors from feedline to ground (what wattage?)

Option 2. Ground the coil in the KW matchbox. (may lose 10/15)

Option 3.  Buy Transmitting coils and install them outside.

Option 4.  Wind my own Coils.


??

CLark

Clark,

The coils I was talking about out of the junk chassis was to use as a test, before you slam dollars down on something from Array Solutions or and find out it DOESN'T work.....  Although I bet it will.

You only need something that provides enough reactance that it doesn't become part of the circuit (the antenna or feeders), and is a DC short.

If you only want to know if it is going to work, grab a choke coil out of a radio that has enough turns to give you the inductance so it is 'invisible'.  Ground your feeders to ground / together.  Install said chokes.  Check receive.  You don't have to TX to test the corona problem (or does it only start AFTER you put fire to the wire...  THAT would be really wierd!).

The antennas you are having problems with are 'floating' in respect to ground, no?  The ones you DON'T are DC grounded.

DC grounded antennas are great.  Static buildup, rain noise, even to an extent lightning crashes, can all be eliminated or at least partially brought down.

--Shane

[WA1GFZ]

My fugly tuner is at DC ground but an approaching storm will flash over the caps with 1/4 inch spacing. The inductance of the coil will blochk a high frequency transient say waveform 3 lightning. This is the reason many tuners use high value noninductive resistors.

[Mike/W8BAC]

Clark,

I have had those Array Solutions inductors in line for 6 years now and they work great. The coil forms show no UV or weather damage. They are virtually invisible from 160 through 10 meters to my system and solve the static problem period. As mentioned you will want a good lightening suppressor as well on each leg.

Give John at Array Solutions a call if you have any doubt. I'm just a very satisfied customer.

Mike

[k4kyv]

I understand they make special johnny ball strain insulators for breaking up the guy wires in broadcast towers for this very purpose.  Some kind of impurity is mixed into the ceramic material so that instead of being perfect insulators, they have several megohms of resistance.

I would recommend a static drain rather than a spark gap.  The gap will still discharge and make a lot of noise in the receiver even if the equipment is protected.

I have had this to happen in winter during blustery weather with wind and snow, and also just as a t-storm front is moving in.  Also at times when it is raining, especially if it is windy at the time.  This static discharge sometimes completely blocks the receiver with white noise.  My 127' vertical has insulators every 18' to make it rf transparent through 40m.  You can imagine all the racket close to 100 isolated sections of cable can create.  Fortunately, this occurs only occasionally.  Sometimes I can get good  reception with the indoor loop or beverage even though the receiver is completely wiped out on the tx antenna.

If you use chokes anywhere but at the rf null point on the coil, make sure it is wound on low loss material, since its inductance will become part of the resonant circuit.  Also, you may notice a  slight shift in tuner settings.  If the rf choke attaches to a cold point on the coil, about any old choke will do and it won't be critical.  The high resistance drain resistors would work, too.  I would experiment and use the highest resistance that is still effective, since it will drain away a small amount of rf as well, unless connected to a cold spot on the coil.

I use a large drain choke from the feed point of the vertical to ground.  It is commercially built, wound on a bakelite form.  One of the balanced tuners has a choke from the cold spot on the  coil to ground.  This one is hand wound on a ceramic form.  See attached photos.

[w3jn]

Guys.  High voltage resistors.  You see 'em at just about every hamfest, and about $5 on eBay.  Brown, with a black internal spiral.  Exactly what's in the Collins 180L3 auto tuner, which was the mate for the 618T 500 watt airborne xmitter and end fed a random wire on the aircraft.

[K1DEU]

   For apx 30 years I have used Several 2 Watt Resistors in series around 300K to 500 K Total at the balanced tuner from each balanced terminal to a station ground rod outside. Yes the tuner box is also grounded and I run 1500 PeP sometimes.

   When we have a high antenna this is necessary to continue listening with out whistles from snow, rain or fog masking even strong stations I.E. "Precipitation Static". Regards  John

[KA1ZGC]

Guys.  High voltage resistors.  You see 'em at just about every hamfest, and about $5 on eBay.  Brown, with a black internal spiral.  Exactly what's in the Collins 180L3 auto tuner, which was the mate for the 618T 500 watt airborne xmitter and end fed a random wire on the aircraft.

Wirewound? I would have thought those would be a bit too inductive, but I guess they must have worked if Collins used them in aircraft tuners.

What about Carborundum resistors? They can take quite a jolt, as long as it's not the physical kind. They also don't have the inherent inductance of a wirewound.

[w3jn]

They have a spiral of carbon in them, and for this purpose it doesn't matter if they're inductive or not.  Several megohms, just to drain of static, will have negiligible inductance compared to the resistance.  In fact, a bit of extra inductance would actually be a benefit here.

[W1VD]

Interesting subject. Was wondering how high resistance value wire wounds could develop meaningful inductance...so pulled a few from the junkbox and put them on the HP Q meter.

100 k ohm / 25 watt Ohmite - no indication of inductance

50 kohm / 25 watt Clarostat VP25K - no indication of inductance

25 kohm / 50 watt Ohmite 270 series - no indication of inductance

250 ohm / 25 watt Ohmite - 35 uH / Q~1

25 ohm / 25 watt Ohmite 270 - 5.6 uH / Q7.5

25 ohm / 25 watt Clarostat VP25KA (adjustable) - 17 uH / Q8.5

2 ohm / 25 watt Ohmite 270 - 3.2 uH / Q23

This is just a Q meter measurement...further study on a bridge and/or a search for resonance might prove interesting. Think it's safe to say the high resistance values that would be used in this application are probably okay. 



 

     

[K1DEU]

  Thanks Jay for helping us all.  And allowing our solid state receiver to have a chance working stably longer.

 How many of us have ben a Ben Franklin ?  And during a precip whistling time placed our finger near one of the balanced line feeders to conclude " I ain't ever doing that again.'

    Its amazing how the Tuner manufacturers and ARRL are out to lunch about suggesting simple safety measures. Must we leave our HV security issues to Fatherland Insecurity ?   Perhaps Not.

  Let us not be afraid of Insurance under (glub) writers and add the resistors quickly during a safe moment!
Of course we could wire the resistors to our metal frame bed for better health !
No frank-ly, there ain't no magnets near my mattress or the chewing gum on my bedposts, but only in my loudspeakers and headphones.
Regards  John

[KA1ZGC]

This is just a Q meter measurement...further study on a bridge and/or a search for resonance might prove interesting.

Well, that's infinitely more measurement than I put into it!

My bad in assuming the resistors Johnny was referring to were wirewound (I judged that book by its cover). A carbon helix would be a whole different ball game.

That, and the fact that I was forgetting the fact that this is a more constant static charge than lightning EMP, and inductance really isn't that much of an issue in that case.

So now I'll go back to being an interested reader. I was a bit more constructive that way.

[ke7trp]

I tried two small Chokes like you suggested.  Just in the listening mode.  This took the noise down.. Then, they both exploded into smoke. I guess this was the voltage hitting.. LOL.  They did work for a little while. I never transmitted through them.  I will need the large coils to drain that huge voltage and current.

Clark

Option 1.  Install 50K resistors from feedline to ground (what wattage?)

Option 2. Ground the coil in the KW matchbox. (may lose 10/15)

Option 3.  Buy Transmitting coils and install them outside.

Option 4.  Wind my own Coils.


??

CLark

Clark,

The coils I was talking about out of the junk chassis was to use as a test, before you slam dollars down on something from Array Solutions or and find out it DOESN'T work.....  Although I bet it will.

You only need something that provides enough reactance that it doesn't become part of the circuit (the antenna or feeders), and is a DC short.

If you only want to know if it is going to work, grab a choke coil out of a radio that has enough turns to give you the inductance so it is 'invisible'.  Ground your feeders to ground / together.  Install said chokes.  Check receive.  You don't have to TX to test the corona problem (or does it only start AFTER you put fire to the wire...  THAT would be really wierd!).

The antennas you are having problems with are 'floating' in respect to ground, no?  The ones you DON'T are DC grounded.

DC grounded antennas are great.  Static buildup, rain noise, even to an extent lightning crashes, can all be eliminated or at least partially brought down.

--Shane

[W1VD]

That's some bad static...

The object is to continually drain it off so it doesn't have the chance to build up. If you've got 25k ohm or higher, 10 or 25 watt wire wound resistors laying around give 'em a try.

   

[k4kyv]

I tried two small Chokes like you suggested.  Just in the listening mode.  This took the noise down.. Then, they both exploded into smoke. I guess this was the voltage hitting.. LOL.  They did work for a little while. I never transmitted through them.  I will need the large coils to drain that huge voltage and current.

Maybe you could rig up something to use this as an alternative energy source.  Put up a  couple of tall towers on insulators, and connect a mesh made of chicken wire between them.  Perhaps you could even get federal funding. 

A dude named Mahlon Loomis back in the 1800's successfully tested a wireless telegraph system between two mountain tops in Virginia, about 20 miles apart, pre-dateding Hertz's experiments.  Each "station" consisted of a kite, later on a wooden tower.  Evidently the static build-up and discharge generated enough radiation that its effect on a galvanometer was measurable at the other site.  But he was thought to be a nutcase or a fraud, so his creation went nowhere.  One more in the long list of failed or ripped off inventors like Tesla, Stubblefield, Fessinden, Armstrong, Farnsworth, etc.

[WA1HZK]

Just my 2 cents. Use the resistors. High value is OK. 47K-470K. Leave them there all the time. When your not using the antenna, ground it. During storms, ground it. Make sure your ground is in good shape because that's where all those loose electrons will be going. If you have a zorch it's just some cheap resistors, just replace them. I have been watching Tina do this for years. Get's rid of the noise and keeps the voltage down enough that zorches are at a minimum.
Keith

[KD6VXI]

I tried two small Chokes like you suggested.  Just in the listening mode.  This took the noise down.. Then, they both exploded into smoke. I guess this was the voltage hitting.. LOL.  They did work for a little while. I never transmitted through them.  I will need the large coils to drain that huge voltage and current.

Clark

Clark,

Glad to see you're finally working on that problem.  I'm really surprised that you didn't blow any of the solid state stuff up over the years with it, but then again, most cheap stuff has the resistor across the antenna jack, or a coil.....  It seems the upper end radios 'eliminated' this, makes ya wonder why.....  I can't see a drawback, the R is high enough that it won't detune anything.

Have fun.  I'd use carbon comp resistors, if you can find them, if that's the way you're going to go, as wirewound will add extra L, which might not be a good thing.  HV rated resistors can be found fairly inexpensively at EBay, or your local Antique Electronics might have some. 

If you go the coils route, I'd suggest 10 times the feeder R amount for each leg, at the lowest freq you operate on.  The biggest problems with coils is, your GOING to have a resonance somewhere.....  And when you do, it's a direct short to ground and the coils get interesting REAL quick.

Pros and cons.

--Shane

[ke7trp]

Tried to use the radio last night.  It was useless. 20DB of static and lightning crashes. I am going to work on this today starting with grounding the coil on the second KW matchbox.  Then, I am going to order the resistors.

Am I to understand I cannot use the HV bleeders I have?  I have 25, 50 and 100w....

Clark

[KD6VXI]

Tried to use the radio last night.  It was useless. 20DB of static and lightning crashes. I am going to work on this today starting with grounding the coil on the second KW matchbox.  Then, I am going to order the resistors.

Am I to understand I cannot use the HV bleeders I have?  I have 25, 50 and 100w....

Clark

Most bleeders are wirewound resistors.  The problem with wirewounds are they introduce inductance (and usually not enough to do what you want here) into the system.

HV carbon resistors are spirally wound (in most cases), but made of carbon (usually), instead of wire.  The carbon has VERY little inductance to add.

You could actually try both...  Use a high value resistor to keep surge current down on the choke....  Although the R would serve to detune the L, possibly causing more problems.

As others have said, too bad you can't harness this..  You have lotsa volts there, and the current isn't anything to sneeze at, either.  I'm bettin it would knock ya on your butt, from what I remember.

--Shane

[K1ZJH]

I must be missing something.. The WW resistors still have a pure resistive, and an inductive reactive value. Wouldn't the two be in series, effectively increasing the impedance above the R value?? I don't see why the inductance wouldn't beneficial?

Pete

[W1VD]

We've all heard the mantra that wire wounds are inductive...so we tend to think that all wire wound resistors are alike and are predominantly inductive. The Q meter measurements show that low resistance value wire wounds do look like inductors with moderate Q but also shows that high resistance value wire wounds do not exhibit much in the way of inductive properties.

If you need to prove this take the highest Q inductor you can measure and put a 50k or 100k resistor in series and then recheck it's performance...

Not sure why a carbon spiral wound resistor would be any different from a nichrome wound resistor...if the resistance is the same and has the same number of 'turns'. It's just a different type of lossy material.

Good point Pete...any inductive reactance just lengthens the impedance vector. In the application we're talking about here the 50k or 100k resistance will dominate.





       

[KD6VXI]

I must be missing something.. The WW resistors still have a pure resistive, and an inductive reactive value. Wouldn't the two be in series, effectively increasing the impedance above the R value?? I don't see why the inductance wouldn't beneficial?

Pete

What about interturn capacitance?  The LC network WILL, at some frequency, become resonant.

As to the R across the L, that's been a way of lowering Q of rf inductors for quite some time....  I've never done it with a WW, but...  Another thing to consider there is this:  HV Resistors are wound like an 'edge wound' inductor (being done with VERY little cross sectional area, using strap).  Wirewounds are wound, like a standard inductor.

The edge wound (like a piece of strap) will have WAY less C between turns than the standard one will...  Hence the properties of the inductor acting different (when looking at a HV rated carbon resistor vs. toaster wire).....


I just measured a 5w, 5ohm, and it had .3uH of inductance across it.

Just looked at it with the VNA, and the same resistor listed above gets squirrelly above 6 mhz.  Would make a great resistor for the use above, but gets all kinds of nice odd resonances that I wouldn't want in my feedline straight to ground above 6 mhz.

--Shane

[WA1GFZ]

I twist the end of the feeders around a pig tail on my service entrance ground when I don't play radio at the new QTH. Yesterday morning there was a storm approaching so thought I would get up and watch the show. I was sitting next to the cat and all of a sudden she lets out a meow. A couple seconds later I hear about a three second arc outside, then ka-bang. I guess the antenna took a bit of a hit and the cat must have felt the voltage change. No the cat's fur wasn't standing on end.