I’ve watched many videos and have read many write-ups on this subject and I must say that this video is one of the best presentations I’ve seen. Nice job, Paul.
That is a great question. I made a video about how to put an HF radio station together. In my station, I have a common mode choke at the antenna and at the transceiver. In this video, it was just at the transceiver side. I think you can get away with just putting the choke on the transceiver side. 73, Paul.
Great video, new ham here about to build my first choke! I have done lots of research online and this is one of the clearest presentations I have seen on the subject. I especially liked that you showed the power ratings of the coax, and the frequency range of the various ferrite composites. I have a nano VNA and I plan to try testing mine after I build it. One thing I have noted with regard to the ubiquedous snap on ferrite cores intended for "EMF" protection , you will almost never find a T31 type (MnZn), they are almost 100% T43 (NiZn) which is why I chose to make the type of choke you demonstrated (I ordered an FT-240-31 which is probably overkill for 100W). 73 Mike.
Hi Paul. Nice video and tutorial. For best performance, where should one place the CMC, near the antenna feedpoint, near the shack passthrough, or maybe one at each location? Thanks!
Thank you for the kind words. That is a good question. In the video I put it right next to the transceiver. But, in my station I actually have two. I have one near the transceiver and one at the antenna. 73, Paul.
So is this better than having 6 palomar T31 snap ons on the end of your coax feeding a homemade DX Commander vertical? What would be better on a Fan Dipole? Thanks!
That’s a good question. It probably would be better. But, I would measure the common mode attenuation with the snap ons and compare to my measurements. 73, Paul.
I'm not seeing any demos of the same signal with and without a choke. Personally I have never seen a better receive with a choke and no improvement over local noise sources. It's quite possible you have ended up with an attenuator. the only way to know is a side by side comparison over the same incoming signal. If the signal drops with the choke in then it's attenuating all of the noise and signals. If the coax or feedline is of good quality and the antenna is tuned at the feedpoint with inductance and capacitance then what is the use of a choke. Almost nobody suffers from RFI these days and even with a choke in and many ferrites on rg213 I see very little improvement over triggering security lights and the like. Seems more like a hindrance and more to go wrong. Transform if you need to for certain antenna designs otherwise tune at the feedpoint. I would only use chokes in emergencies. The one time I found a 1:1 unun worked well was when experimenting with an antenna build with an insulated mast. In this case with no earth coming from a mast it is extra important that the antenna is well tuned and balanced to 50 ohms by adding the correct amount of capacitance vs inductance. If you can tune your design to work well with low swr and it has no earthing you are essentially tuning an unbalances system to work more like a balanced one yet it still matches the unbalanced coax and radio. If you can get good results without a metal mast and only use counterpoises designed into the antenna itself then you have made a very good antenna and no choke should be necessary. All videos show how the choke attenuates unwanted signals or current by showing in on a vna but there are very few videos showing the difference in real world scenarios.
Thank you for sharing your experiences. I also have had antenna systems that I did not notice a difference with common mode chokes. But, I’ve definitely noticed a big difference with other antennas systems. In this specific example, this is not an attenuator since we have measured the insertion loss to be 0.1 db. You can see in this example that the signals are not being attenuated, the common mode noise is being attenuated. Have a good weekend, Paul.
lol. I take it that you don’t use a CMC. 73, Paul.
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A 1 to 1 balun certainly does not hurt when you move a few hundred kilohertz outside the tuned resonance of an antenna/radiator and have a bit of imbalance.. I see them acting more like a diode in a DC circuit thus being a one way valve.. I have done this both ways using wire wound cores and clamp on cores especially when a horizontal antenna can not be elevated to at least a half wave over the ground or a half wave away from ground clutter like trees and buildings.. This is far easier and cheaper than chopping down trees and bushes while placing the antenna at 35 to 100 feet above the ground or adding a half mile of ground radials to most verticals.. Another option is to have capacitance between the feed point of an antenna and a good ground.. Bad news is this method require that capacitance to be adjusted when changing bands or moving more than 100 kc's and the distance from feed point to ground has to be very short to prevent reactance.. Thing is most people already know their antenna is not and never will be perfect so why bother since the easy fix is exactly that..
![Build Your Own End-Fed Half-Wave Antenna [A Complete Guide to EFHW]](http://i.ytimg.com/vi/SBrc1DpMk_w/mqdefault.jpg)
I’ve watched many videos and have read many write-ups on this subject and I must say that this video is one of the best presentations I’ve seen. Nice job, Paul.
Glad you enjoyed it and thank so much for the kind words. 73, Paul.
Excellent instructional video, new subscriber here. Keep up the great work!
Thanks for the sub! 73, Paul.
Very nice demonstration. Thank you very so much!
Thank you, I’m glad you enjoyed. 73, Paul.
Excellant presentation of the why, testing and use of a DIY common mode choke.
Glad it was helpful! 73, Paul.
Thanks for this nice video, i'll have one question were do you placed the common choke under the antenne or direct after the transciever?
That is a great question. I made a video about how to put an HF radio station together. In my station, I have a common mode choke at the antenna and at the transceiver. In this video, it was just at the transceiver side. I think you can get away with just putting the choke on the transceiver side. 73, Paul.
Beautiful result!!!🎉🎉🎉
Thank you! 73, Paul.
Great video, new ham here about to build my first choke! I have done lots of research online and this is one of the clearest presentations I have seen on the subject. I especially liked that you showed the power ratings of the coax, and the frequency range of the various ferrite composites. I have a nano VNA and I plan to try testing mine after I build it. One thing I have noted with regard to the ubiquedous snap on ferrite cores intended for "EMF" protection , you will almost never find a T31 type (MnZn), they are almost 100% T43 (NiZn) which is why I chose to make the type of choke you demonstrated (I ordered an FT-240-31 which is probably overkill for 100W). 73 Mike.
Hi Mike, thank you so much for the comment. I did not know that about the snap on EMF filters. I hope to catch you on the air. 73 Paul.
Hi Paul. Nice video and tutorial. For best performance, where should one place the CMC, near the antenna feedpoint, near the shack passthrough, or maybe one at each location? Thanks!
Thank you for the kind words. That is a good question. In the video I put it right next to the transceiver. But, in my station I actually have two. I have one near the transceiver and one at the antenna. 73, Paul.
@@W2PAK Nice. That's what I'll do. I read that somewhere and considering the dynamics at work, it made good sense to me. Thanks again.
73, Gary W1GWL
I use Halibut fixture for messing my common mode chokes. Otherwise you did an excellent job showing the benefits of using them.
Haha. Did the auto caption do something silly??
Please make a link for the 2 charts for what to use making the chokes, different power levels etc... liked the video, easy to understand 👍
That’s a very good suggestion, I added it to the description. 73, Paul.
@W2PAK thanks for adding the charts so quickly, I'm sure it will be helpful to others as well, 73s AA2BD
So is this better than having 6 palomar T31 snap ons on the end of your coax feeding a homemade DX Commander vertical? What would be better on a Fan Dipole? Thanks!
That’s a good question. It probably would be better. But, I would measure the common mode attenuation with the snap ons and compare to my measurements. 73, Paul.
Bookmarked
I’m glad that you enjoyed it. 73, Paul.
I'm not seeing any demos of the same signal with and without a choke. Personally I have never seen a better receive with a choke and no improvement over local noise sources. It's quite possible you have ended up with an attenuator. the only way to know is a side by side comparison over the same incoming signal. If the signal drops with the choke in then it's attenuating all of the noise and signals.
If the coax or feedline is of good quality and the antenna is tuned at the feedpoint with inductance and capacitance then what is the use of a choke. Almost nobody suffers from RFI these days and even with a choke in and many ferrites on rg213 I see very little improvement over triggering security lights and the like. Seems more like a hindrance and more to go wrong. Transform if you need to for certain antenna designs otherwise tune at the feedpoint. I would only use chokes in emergencies.
The one time I found a 1:1 unun worked well was when experimenting with an antenna build with an insulated mast. In this case with no earth coming from a mast it is extra important that the antenna is well tuned and balanced to 50 ohms by adding the correct amount of capacitance vs inductance. If you can tune your design to work well with low swr and it has no earthing you are essentially tuning an unbalances system to work more like a balanced one yet it still matches the unbalanced coax and radio. If you can get good results without a metal mast and only use counterpoises designed into the antenna itself then you have made a very good antenna and no choke should be necessary.
All videos show how the choke attenuates unwanted signals or current by showing in on a vna but there are very few videos showing the difference in real world scenarios.
Thank you for sharing your experiences. I also have had antenna systems that I did not notice a difference with common mode chokes. But, I’ve definitely noticed a big difference with other antennas systems. In this specific example, this is not an attenuator since we have measured the insertion loss to be 0.1 db. You can see in this example that the signals are not being attenuated, the common mode noise is being attenuated. Have a good weekend, Paul.
Ah yes, common mode chokes and ferrites on cables, the homeopatic cure for everything when one does not know what is the problem.
lol. I take it that you don’t use a CMC. 73, Paul.
A 1 to 1 balun certainly does not hurt when you move a few hundred kilohertz outside the tuned resonance of an antenna/radiator and have a bit of imbalance.. I see them acting more like a diode in a DC circuit thus being a one way valve.. I have done this both ways using wire wound cores and clamp on cores especially when a horizontal antenna can not be elevated to at least a half wave over the ground or a half wave away from ground clutter like trees and buildings.. This is far easier and cheaper than chopping down trees and bushes while placing the antenna at 35 to 100 feet above the ground or adding a half mile of ground radials to most verticals.. Another option is to have capacitance between the feed point of an antenna and a good ground.. Bad news is this method require that capacitance to be adjusted when changing bands or moving more than 100 kc's and the distance from feed point to ground has to be very short to prevent reactance.. Thing is most people already know their antenna is not and never will be perfect so why bother since the easy fix is exactly that..
Dude, you clearly haven't seen an UHF antenna on NanoVNA without and with a ferrite clamp.
Very well explained. Thank you!
Glad it was helpful! 73, Paul.