Hi Dave, I would like to point out some facts about the content of the video you presented here. 1. It's about having a 1:1 Common Mode Current (CMC) Choke on the power lines to the garage door opener. He said it started lighting up when he used higher RF power. It's very obvious that he has lot of CMC flowing down through the outer aspect of the shield braid of the coaxial cable that feeds his antenna; the CMC (RF in the shack) also flows down along the power lines of his entire house. Maybe his shack is very near to the garage or the power lines are being shared in common. He must, first of all investigate the reason for the excessive CMC that maybe due to operating a vertical antenna or OCF dipole or something like that. An antenna current meter hooked up on the coaxial cable would tell the relative magnitude of the CMC flowing on the coaxial cable shield. Other equipments sharing the common mains outlet may become faulty. 2. You said there is no consensus in the world of torroids (ferrite or iron powder) You are thoroughly wrong. Decades ago different manufacturers produced in different dimensions and some with colours painted on them. But now there are mainly two manufacturers in the US, namely Micrometals (mainly iron powder cores) and the Fair-rite (ferrites); Amidon is not a manufacturer but only a vendor. Because the name Amidon is being mentioned everywhere in the ARRL book people are of the wrong opinion that you should use Amidon cores for your radio projects. 3.Iron powder cores are given colour codes and it's universal. Ferrites are ceramics containing Ni-Zn or Mn-Zn and other metals in trace quantities. The process of manufacturing is akin to pottery and has many classified receipes. And it too is well standardized with predictable behaviour in a circuitry based on the physical cum electrical parameters given in the datasheet. The ferrites come in plenty of flavours and hence can't be printed or labelled on them as you suggested. And they are highly brittle you know. 4. He has used #31, a Ni-Mn ferrite with high initial permeability that is considered an all rounder for making CMC Choke for the HF, V/UHF amateur bands. You can use #43 for the HF and #61 for the V/UHF frequencies for suppressing the CMC. 5. Differential Mode Current flowing in the coaxial cable or parallel/twin flex wire would be producing magnetic flux whose fields would cancel each other because the currents are of the same magnitude but of opposite polarity. But an inductor would pose very high (inductive) reactance for the CMC that tends to flow down the outer surface of the coaxial cable due imbalance in the antenna system. The coaxial cable starts radiating while transmitting and becomes a part of receiving element (apart from the dipole elements); yes the antenna system becomes not a dipole but a TRIPOLE. 6. He asked about the magnitude of reactance offered by the CMC. But you showed the bulk of the material it should have with your fingers 🙄 Yes, you can calculate it by using the formula for inductive reactance, Xl, which is, 2pi FL. Each mix has a definite initial permeability value (850, in case of #43) and a torroid of 2.4" od would hold specific number of turns of wire of specific dimension that can be reckoned from the datasheet. It's traditional that the reactance should be at least 4 times the characteristic impedance of the system (200 ohm for a 50 ohm system) But it's better to have in terms of few thousands of ohms for assured suppression for a given range of frequencies. Everything can be calculated. There's nothing arbitrary here. De VU2RZA. NB: I feel very sorry to point out that, of late, your videos lack the correct and necessary information to the question asked. You may prepare well for it.
Dave: I used to install networks back in the 90's and had a customer call me because another consultant couldn't get their PC in the back room, and they got my name. I ran my Fluke cable analyzer to see if I had a short or bad T connector. None of the above. So I was sitting there scratching my head and I looked down at the cable and saw the familiar Radio Shack branding. A closer look identified it as RG-59, 75 ohm cable. I told them that I will replace it with RG-58 and it would work, guaranteed. It did fix the problem and I had a customer for years thereafter. Yep, RG-6 would error out for a bunch of reasons, not the least of which is the collision retries. The timing gets all screwed up with RG-59. By the way, it's not just the turns/twists that make a data cable over voice. It is also the insulation material. This was all expressed in a document for the electrification of farmland, and the like. I cannot remember its name exactly but it had something to do with Rural Electrification. It's very interesting. 73, Marc - N6UNX
Hello. I had been trying torroids ft240 mix 31 or 43 to create an RF Choke for VHF , testing with the gain parameter using both ports on nanovna, had wind from 2 turns to 13 turns, creating not usefull resistance (ohms) ... I know mix 31 or 43 are most useful in HF, ... Has anyone create a succesful RF choke with Toroids for 144mhz ??? tks 73
I think the bigger question is what IS the real value of the mostly unmarked toroid's? It's sad when you find these in most devices and don't know their value so then can't really reuse them with any confidence. Would it be worth maybe winding a known number of turns on it and then use the math to figure out it's mix and so on? Seems like there must be something like an Amp-Clamp device that you could snap around the toroid and give its values? I can't remember ever seeing anything like that. Seems valuable? Joe AG4QC
Hi, you can put some 10 turns and measure the inductance and hence the inductive reactance it would offer for the frequency of operation. Al (average inductance) per n^2 is for the ferrite/iron powder cores are given in the datasheet by the manufacturers Micrometals/Fair-rite. From the Al value you can calculate the inductance for 10 turns. If it's in the nearby vicinity with the value you obtained by measuring on the "L/C" meter you can be sure that the torroid in your hand is similar to the one you referred to in the datasheet. This way you can come to a conclusion about the mix of the material. De VU2RZA
Hi, and you can make an antenna current clamp meter. You can use the snap on (snap-it) type ferrite cylinder of say, 13 mm internal diameter so that it can be clamped on the coax like RG-213 cable. Put 10 turns on the lower half alone and get it rectified by a diode like 1N 34A, BAT85, 1N5771 or 1N4148 (forward drop voltage 200mv, 400mv and 600mv respectively). You can feed it through a potentiometer to a 100 (or less) micro meter for a relative current reading. If you are keen enough you can calibrate it too. You can refer to G3SEK's page for some construction ideas. And for your information MFJ is selling an antenna clamp on current meter that's calibrated. De VU2RZA
I prefer Fair-Rite products. Do have the manufacturer name on them an you can buy by mix. I find TDK to be way inferior, but still better than the unknown Amazon products
Good job. Just keep in mind that CMC (common mode currents) are looking to return to their source, Like anything else. When you "block" the path these currents are using, just beware its still trying to get to its source (usually via ground). And it might find another path. And that may cause some entirely diferent issue. Sonewhere else...Just something to be aware of. Great video..
Powdered iron material is color coded but ferrite is not and I've never understood that either! DX Engineering paints a color stripe on their ferrite and you could use a silver sharpie which I do to mark the material number.
So he placed his toroid in the AC line (2 wires) powering his garage door opener. And it blocked (canceled) the Rf that was on both wires powering the door opener. Common mode rejection and had no effect on the ac powering of the door opener? Which is very interesting to me. If I understand this correctly. The ac is very low frequency and the rf very high frequency. But the ac has no common mode across both power wires. But the rf interference does. So the toroid on the power line cancels the rf at that point in the garage or in the entire house ac circuitry.?
Yes, that is about it, the AC line is differential mode and unaffected by the toroid, the common mode RF sees the choke as a high impedance. A UK article you may find interesting is by GM3SEK. Very little changes if you model a US version on similar. FWIW this approach can be effective in reducing noise on your radio from appliances too.
![[UNCUT] “บอสณวัฒน์” ลากไส้!! ใครหนุนหลัง "แม่ตั๊ก ป๋าเบียร์" I คนดังนั่งเคลียร์ I 30 ก.ย. 67](http://i.ytimg.com/vi/QlD7mU2KKRk/mqdefault.jpg)
Hi Dave, I would like to point out some facts about the content of the video you presented here.
1. It's about having a 1:1 Common Mode Current (CMC) Choke on the power lines to the garage door opener.
He said it started lighting up when he used higher RF power.
It's very obvious that he has lot of CMC flowing down through the outer aspect of the shield braid of the coaxial cable that feeds his antenna; the CMC (RF in the shack) also flows down along the power lines of his entire house.
Maybe his shack is very near to the garage or the power lines are being shared in common.
He must, first of all investigate the reason for the excessive CMC that maybe due to operating a vertical antenna or OCF dipole or something like that.
An antenna current meter hooked up on the coaxial cable would tell the relative magnitude of the CMC flowing on the coaxial cable shield.
Other equipments sharing the common mains outlet may become faulty.
2. You said there is no consensus in the world of torroids (ferrite or iron powder)
You are thoroughly wrong.
Decades ago different manufacturers produced in different dimensions and some with colours painted on them.
But now there are mainly two manufacturers in the US, namely Micrometals (mainly iron powder cores) and the Fair-rite (ferrites); Amidon is not a manufacturer but only a vendor. Because the name Amidon is being mentioned everywhere in the ARRL book people are of the wrong opinion that you should use Amidon cores for your radio projects.
3.Iron powder cores are given colour codes and it's universal.
Ferrites are ceramics containing Ni-Zn or Mn-Zn and other metals in trace quantities. The process of manufacturing is akin to pottery and has many classified receipes.
And it too is well standardized with predictable behaviour in a circuitry based on the physical cum electrical parameters given in the datasheet.
The ferrites come in plenty of flavours and hence can't be printed or labelled on them as you suggested. And they are highly brittle you know.
4. He has used #31, a Ni-Mn ferrite with high initial permeability that is considered an all rounder for making CMC Choke for the HF, V/UHF amateur bands.
You can use #43 for the HF and #61 for the V/UHF frequencies for suppressing the CMC.
5. Differential Mode Current flowing in the coaxial cable or parallel/twin flex wire would be producing magnetic flux whose fields would cancel each other because the currents are of the same magnitude but of opposite polarity.
But an inductor would pose very high (inductive) reactance for the CMC that tends to flow down the outer surface of the coaxial cable due imbalance in the antenna system.
The coaxial cable starts radiating while transmitting and becomes a part of receiving element (apart from the dipole elements); yes the antenna system becomes not a dipole but a TRIPOLE.
6. He asked about the magnitude of reactance offered by the CMC. But you showed the bulk of the material it should have with your fingers 🙄
Yes, you can calculate it by using the formula for inductive reactance, Xl, which is, 2pi FL.
Each mix has a definite initial permeability value (850, in case of #43) and a torroid of 2.4" od would hold specific number of turns of wire of specific dimension that can be reckoned from the datasheet.
It's traditional that the reactance should be at least 4 times the characteristic impedance of the system (200 ohm for a 50 ohm system)
But it's better to have in terms of few thousands of ohms for assured suppression for a given range of frequencies. Everything can be calculated. There's nothing arbitrary here.
De VU2RZA.
NB: I feel very sorry to point out that, of late, your videos lack the correct and necessary information to the question asked.
You may prepare well for it.
Well said. I want to point out once more: there are iron powder cores and ferrite cores on the market. These are not the same!
Dave: I used to install networks back in the 90's and had a customer call me because another consultant couldn't get their PC in the back room, and they got my name. I ran my Fluke cable analyzer to see if I had a short or bad T connector. None of the above. So I was sitting there scratching my head and I looked down at the cable and saw the familiar Radio Shack branding. A closer look identified it as RG-59, 75 ohm cable. I told them that I will replace it with RG-58 and it would work, guaranteed. It did fix the problem and I had a customer for years thereafter. Yep, RG-6 would error out for a bunch of reasons, not the least of which is the collision retries. The timing gets all screwed up with RG-59.
By the way, it's not just the turns/twists that make a data cable over voice. It is also the insulation material. This was all expressed in a document for the electrification of farmland, and the like. I cannot remember its name exactly but it had something to do with Rural Electrification. It's very interesting.
73,
Marc - N6UNX
I feel like this one should have Chinese subtitles….
Anyway, thanks for another interesting video!
Hello. I had been trying torroids ft240 mix 31 or 43 to create an RF Choke for VHF , testing with the gain parameter using both ports on nanovna, had wind from 2 turns to 13 turns, creating not usefull resistance (ohms) ... I know mix 31 or 43 are most useful in HF, ... Has anyone create a succesful RF choke with Toroids for 144mhz ??? tks 73
I think the bigger question is what IS the real value of the mostly unmarked toroid's? It's sad when you find these in most devices and don't know their value so then can't really reuse them with any confidence. Would it be worth maybe winding a known number of turns on it and then use the math to figure out it's mix and so on? Seems like there must be something like an Amp-Clamp device that you could snap around the toroid and give its values? I can't remember ever seeing anything like that. Seems valuable? Joe AG4QC
Hi, you can put some 10 turns and measure the inductance and hence the inductive reactance it would offer for the frequency of operation.
Al (average inductance) per n^2 is for the ferrite/iron powder cores are given in the datasheet by the manufacturers Micrometals/Fair-rite. From the Al value you can calculate the inductance for 10 turns.
If it's in the nearby vicinity with the value you obtained by measuring on the "L/C" meter you can be sure that the torroid in your hand is similar to the one you referred to in the datasheet.
This way you can come to a conclusion about the mix of the material.
De VU2RZA
Hi, and you can make an antenna current clamp meter. You can use the snap on (snap-it) type ferrite cylinder of say, 13 mm internal diameter so that it can be clamped on the coax like RG-213 cable.
Put 10 turns on the lower half alone and get it rectified by a diode like 1N 34A, BAT85, 1N5771 or 1N4148 (forward drop voltage 200mv, 400mv and 600mv respectively). You can feed it through a potentiometer to a 100 (or less) micro meter for a relative current reading.
If you are keen enough you can calibrate it too. You can refer to G3SEK's page for some construction ideas.
And for your information MFJ is selling an antenna clamp on current meter that's calibrated.
De VU2RZA
I prefer Fair-Rite products. Do have the manufacturer name on them an you can buy by mix. I find TDK to be way inferior, but still better than the unknown Amazon products
Good job. Just keep in mind that CMC (common mode currents) are looking to return to their source, Like anything else.
When you "block" the path these currents are using, just beware its still trying to get to its source (usually via ground). And it might find another path. And that may cause some entirely diferent issue. Sonewhere else...Just something to be aware of.
Great video..
Powdered iron material is color coded but ferrite is not and I've never understood that either! DX Engineering paints a color stripe on their ferrite and you could use a silver sharpie which I do to mark the material number.
Material 31
Yet another "placebo" video that doesn't amount to anything!
So he placed his toroid in the AC line (2 wires) powering his garage door opener. And it blocked (canceled) the Rf that was on both wires powering the door opener. Common mode rejection and had no effect on the ac powering of the door opener? Which is very interesting to me. If I understand this correctly. The ac is very low frequency and the rf very high frequency. But the ac has no common mode across both power wires. But the rf interference does. So the toroid on the power line cancels the rf at that point in the garage or in the entire house ac circuitry.?
Yes, that is about it, the AC line is differential mode and unaffected by the toroid, the common mode RF sees the choke as a high impedance. A UK article you may find interesting is by GM3SEK. Very little changes if you model a US version on similar.
FWIW this approach can be effective in reducing noise on your radio from appliances too.
@@g0fvt the rf “sees” the toroid as a high impedance choke… or creates counter emf that cancels the common mode rf.. which one?
@@iamhe999 hi, you can refer to my comment to Dave above.
De VU2RZA
@@iamhe999 you could argue that both are true. FWIW the work of G3TXQ on common mode impedance of similar chokes is worth looking at.
thank you for your persistence as always