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Author Topic: Ladder Line Static Drain/Shunt Inductors  (Read 37804 times)
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ke7trp
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« Reply #25 on: April 29, 2013, 10:44:07 AM »

This is why I dont suggest using a thin wire plate choke. If you get anywhere near a hot spot of the plate choke, its going to open at the high antenna current.  From $25 to $35 for the large gauge wire AS chokes, I dont think its worth it to chance it with open wire line antennas.  Then, I think they would probably open up due to near by strikes and static electricity in this area.  Those chokes are putting very high voltage and current to ground before a monsoon storm or a dust storm rolls through.  But, maybe I dont know anything like steve says.  That might be true since Steve is never wrong. Ever.

C

C and all,

Array Solutions states that their anti static coils are rated as such:

1.8 MHz = inductive reactance of 850 ohms.  I believe the equates to about 75 uH.

3.5 MHz = inductive reactance of 1,900 ohms.  I think this equates to about 88 uH.

To me this seems backwards.  What do you think?

Chuck

  Chuck,

  Data like what you posted that goes non-linear sure suggests that a resonance is fast approaching. The resonance(s) come from distributed capacitance turn to turn. Remember for parallel resonance, below resonance the coil has inductive reactance, and above resonance the thing behaves more like a capacitor. The reactance could still be high though, and the device still do the intended job. If the reactive current were to get high at certain frequencies, then a small gauge coil could certainly heat up, and possibly fry. One way around this would be to use a heavy gauge coil, and hope the coils contribution to the  complex feedline reactive load could be offset by another setting of the upstream tuner. Having a choke in there designed to be resonant free in any ham band 160-10m sure seems to be an advantage. If a plate choke has these characteristics, then it would not burn up even if the wire used had a small cross section.

Jim
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Steve - K4HX
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« Reply #26 on: April 29, 2013, 08:54:17 PM »

It's not about me Clark. It's about you and your incorrect info.

People have been using resistors as static drains for decades. This is nothing that can be argued. It's been done. Now you come  along, a guy that doesn't even understand simple concepts like, self resonance and inductive reactance, and you want us to believe that you know better. That is laughable.

It's obvious to anyone with a basic understanding of what's going on here that the antenna current DOES not flow through the static chokes. Why waste our time with such nonsense? You only serve to make yourself look silly.

Others have asked you questions in this thread. You did not answer them. Why not? Do you not have the answers? You should given your claim of preeminent knowledge. Or are you just being rude and ignoring the questions? Either way, you are adding zero to the discussion.

So, you aren't arguing with me. You are arguing with decades standard practice and well known basic electronics and RF knowledge developed by people far smarter than me. The fact that you want to try to make this personal shows you've got nothing of substance on the actual technical subject.

Take your smart ass confrontational crap somewhere else.
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KA2DZT
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« Reply #27 on: April 29, 2013, 10:57:54 PM »

I'm not so sure that Clark's comments are wrong.

Given,  a high value resistor will drain off a steady build-up of static charges.  With a resistor you may want to consider the limited voltage ratings of ordinary resistors.  So, you could use a string of them to increase the overall voltage handling ability.  Also, carbon or Globars might be needed to avoid resonant points that might occur with wire-wound types.  You could use non-resonant wire-wound types, not sure if they are still made, but I have many of them 2K 50watt.

Clark speaks to using heavier gauge wire chokes to avoid burn-out from the large antenna currents.  Well, we all know that the antenna current is not flowing through these shunt chokes.

In Clark's last post he mentions getting near a "hot spot of the plate choke".  What does he mean by "hot spot"??

I'm going to assume he means a self-resonant frequency in the choke.  The resonance is caused by the distributive capacitance between the windings.  This capacitance is in series with the inductance of the coil.  Series resonant circuits have a very low impedance, allowing for very high currents to flow.

So, maybe Clark is not so wrong when he is concerned about high antenna currents flowing through thin-wire plate chokes.  Of course, we hope that a good plate choke doesn't have any self-resonant points, but who knows for sure.

Just my .02 cents, now $3.85 with inflation.

Fred

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« Reply #28 on: April 30, 2013, 07:49:29 AM »

I'm going to assume he means a self-resonant frequency in the choke.  The resonance is caused by the distributive capacitance between the windings.  This capacitance is in series with the inductance of the coil.  Series resonant circuits have a very low impedance, allowing for very high currents to flow.

  Fred,

   Lets ponder on what you just said. I agree that the coil resonance will be from turn to turn capacitance, but that resonance is parallel resonance, and not series resonant. So at || resonance we have a higher impedance (a good thing), but what happens as we go up in frequency from there? Classical parallel resonance above the resonant frequency shows a increasing capacitive load. But wait, this isn't coil current..instead it is reactive capacitor current from the turn to turn capacitance.

   The area where I am struggling to understand is the loss characteristic of the distributed turn to turn capacitance, and whether a single layer linear wound coil would only have one resonant point, or multiple?

   So when someone uses a plate choke in its intended application (plate circuit), and it fails, is the failure due to a parallel resonance in one of the sections where at resonance the turn to turn voltage soars beyond the wire insulation rating?

   Consider series resonance where at resonance we have a low impedance. Below the resonant point there is a capacitive circuit, and above that we have an inductive circuit. So this seems N/A to the topic. Take a grid dip meter, and a 0.01uf disc capacitor Wrap the leads around the GDO coil form, and twist the ends together. Then sweep the frequency. You should see a sharp series resonance (the inductance is the short wire leads) at about 7 Mhz. So consider that when you use a .01 uf bypass capacitor at the upper reaches of HF....It looks like an inductor!

Sorry for my rambling...

Jim
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K3ZS
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« Reply #29 on: April 30, 2013, 08:11:26 AM »

Because of the above, critical RF circuits would have a .01 cap in parallel with a 100 pF.
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« Reply #30 on: April 30, 2013, 10:17:56 AM »

Jim,

Thanks for your input on my comments.  I pondered on which resonance it is, series or parallel.  I finally decided to go with series.  I knew I would get some different opinions.  At this point I'm not really sure one way or the other.  I'm going to try to research this further.  I would think even with parallel resonance you still get some high circulating currents.

After Steve beat the hell out of Clark I had to do something to try to save his behind. Grin

I'll re-read and study further your comments.  You may very well be right as I never had any of my plate chokes burn up to see what actually occurs.

Fred
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« Reply #31 on: April 30, 2013, 10:40:40 AM »


I'll re-read and study further your comments.  You may very well be right as I never had any of my plate chokes burn up to see what actually occurs.

Fred



Fred, if you need any help burning components up just let me know. I would be glad to help.
Dave
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KM1H
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« Reply #32 on: April 30, 2013, 11:01:43 AM »

Quote
In Clark's last post he mentions getting near a "hot spot of the plate choke".  What does he mean by "hot spot"??

I'm going to assume he means a self-resonant frequency in the choke.  The resonance is caused by the distributive capacitance between the windings.  This capacitance is in series with the inductance of the coil.  Series resonant circuits have a very low impedance, allowing for very high currents to flow.

I suspect he is concerned that most modern plate chokes have a resonance on 11M Grin

At $20 the Ameritron has the best price and highest reactance on all ham bands while maintaining a very low DC resistance.  Do regular resistance checks especially during T storm season.

Carl
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« Reply #33 on: April 30, 2013, 11:14:49 AM »

Dave,

Thanks,  I can always count on you for much needed help.

Jim,

I just located some info on this subject.  In the ARRL Handbook there is a section on distributive circuit elements, page 53 in the 1973 book.

It seems that every capacitor is a series tuned circuit with any inductance the cap may have.  You are right, it further states that every inductor is a parallel tuned circuit with its distributive capacitance.

So, I guess at this point, Clark is on his own. Grin

I should have done some research before I decided on series resonance in my previous post.

Fred
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« Reply #34 on: April 30, 2013, 12:18:25 PM »


I should have done some research before I decided on series resonance in my previous post.

Fred

It's OK Fred. You still have more transformers in your transmitter than everyone else.
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KA2DZT
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« Reply #35 on: April 30, 2013, 12:40:35 PM »

Thanks Dave, now I feel much better.

You're right about the transformers, but, not everyone is actually connected to anything. Grin

Fred
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W2PFY
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« Reply #36 on: April 30, 2013, 02:16:49 PM »


Quote
Do regular resistance checks especially during T storm season.


Ok, I'll show my ignorance, would the idea of using a small fuse at the ground end of the inductor, perhaps one amp, serve  an indicator that the antenna took a hit? This is of course for static drain and not lighting protecting. Who would regularly check the RFC anyway, so this fuse displayed in an open area could be what is needed for these pesky HV spikes Huh Huh Huh   
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Gito
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« Reply #37 on: May 01, 2013, 12:20:03 AM »

Hi

Ladder line means Twin balanced Line?

When We used link coupling does not it mean A coil  connected between this

two wire ladder line as the link coupling  to the coil  system  from the transmitter

That means a floating coil?

How if we Ground the CT of this coil to Ground.

Gito.N
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« Reply #38 on: May 01, 2013, 01:15:31 AM »

Gito

A center tapped coil that is grounded at the CT would certainly seem to be the ideal thing to do.  Not sure what exact tuner circuits are generally used with ladder line.

Fred
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Gito
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« Reply #39 on: May 01, 2013, 07:42:16 AM »

Hi Fred

Maybe this tuner will Help,found this circuit in an Old Hand book


Gito


* link.jpg (365.25 KB, 3504x2552 - viewed 787 times.)
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W2VW
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« Reply #40 on: May 01, 2013, 10:56:31 AM »

Hi

Ladder line means Twin balanced Line?

When We used link coupling does not it mean A coil  connected between this

two wire ladder line as the link coupling  to the coil  system  from the transmitter

That means a floating coil?

How if we Ground the CT of this coil to Ground.

Gito.N

Hello Gito,

   A center tap to ground would work. The problem is any error in center tap will cause the coupler to introduce common mode feedline current.

Many of these couplers are homebrew without regard to perfect symmetry. Symmetry is not necessary unless grounding the center tap of the coil.

A further problem exists with series tuning as the center tap would not be connected to anything. See series and parallel link tuning diagrams.

2VeryWeak
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Gito
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« Reply #41 on: May 01, 2013, 08:54:09 PM »

Hy Every Weak

You are right .But I found this "solution" after reading the old Amateur hand book
ARRL,
The design is for Home brew,so I think they has already know about this grounding center Tap , to find a"perfect" balance

And the circuit can be used as Parallel Tuning Or Series tuning with a  change in the Circuit

Gito


* link coupling.jpg (450.31 KB, 3504x2484 - viewed 758 times.)
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Gito
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« Reply #42 on: May 02, 2013, 04:30:16 AM »

Hi

After rereading this parallel ling coupling and Series link coupling .I found out that we used Series link coupling when we had a low impedance ( load) at the output of the Tuner.

But with this Parallel link coupling ,we can used as an alternative,set the feeder taping coil point close to  the CT of the Coil. to get A low impedance Output

Depending the Taping feeder point,We can get a high impedance output or A low impedance output

So A series link Coupling is not needed.


Gito


* link coupling 3.jpg (685.07 KB, 3504x2552 - viewed 788 times.)
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W2VW
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« Reply #43 on: May 02, 2013, 08:55:42 PM »

Hi

After rereading this parallel ling coupling and Series link coupling .I found out that we used Series link coupling when we had a low impedance ( load) at the output of the Tuner.

But with this Parallel link coupling ,we can used as an alternative,set the feeder taping coil point close to  the CT of the Coil. to get A low impedance Output

Depending the Taping feeder point,We can get a high impedance output or A low impedance output

So A series link Coupling is not needed.


Gito

Series coupling is used where component limitations begin to waste power. Experimenting with QRO can be very instructive concerning antenna coupler component limitations.

Again, the center tap becomes a liability if the radio equipment is located in a modern neighborhood. Feedline isolation can make the difference between hearing many as well as staying out of RF susceptible consumer junk.

Simple resistors do the trick here. If building from scratch some type of center tap arrangement could be used. Always many ways to skin the cat Gito.

I gave up on link coupled designs back when running a BC-610 on 160 into an 80 meter length doublet. This was after trying a lot of configurations. Some made fine photographs (R.U. there VJB?). The AG6K type coupler (yes Frank we all know he didn't invent it) allows the entire antenna to be run at DC ground with only the addition of a parallel R.F. choke at the predictable 50 ohm port.

I get plenty of very intense precipitation static directly off the Atlantic. 
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Gito
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« Reply #44 on: May 03, 2013, 10:17:43 PM »

Hi

I know that You have a lot of experience trying to Used link coupling,

But as I wrote before after rereading this books I found this picture in ARRL hand book (CT at the Coil   X point)

An article of Parallel and link Coupling


It reads on 7 Mhz for Example the Impedance is Low and the series circuit of the figure 13.35a would be used ..............Alternatively the Parallel tuned coupling circuit fig 13, 55 b  could  be used  and the feeder taping points  set close to the center of the coil (RSGB) hand book

The conclusion I have after reading it We don not need a series  link coupling

So it is not my only opinion,but ARRL and RSGB book has the same opinion


Gito





* IMG00687-20130503-2018.jpg (157.59 KB, 1600x1200 - viewed 758 times.)

* IMG00689-20130503-2021.jpg (180.56 KB, 1600x1200 - viewed 787 times.)
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Steve - K4HX
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« Reply #45 on: May 04, 2013, 07:16:07 PM »

Yes, you can tap down on the coil in parallel link arrangement and you will be able to tune the system. At some point the Q becomes too high and it is usually better to go with series tuning or change the length of the feedline.
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Gito
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« Reply #46 on: May 04, 2013, 10:33:22 PM »

Hi

You are right Steve , here I attached another picture from  an article  Tuna X-treme    

Just showing people does used CT ground   , I found it in   Super Massive Tuna  

- WZ5Q



Gito


* WZ5Q LCT.jpg (118.5 KB, 768x614 - viewed 788 times.)
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aa5wg
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« Reply #47 on: May 07, 2013, 09:12:34 PM »

Thank you to all for the static drain information.

Chuck
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