#82: Real Antenna Impedance, Maximum Balun Stress, and More

This topic is quite complicated and not well understood. I hope the video and the downloadable files allow you to experiment further.
www.w0qe.com
www.w0qe.com/Si... to download files in this video

[@dlpoinsett]

Larry, I can't thank you enough for these recent videos on modeling power dissipation in baluns with SimSmith. It has been a real eye-opener. There is so much confusion about how baluns work. All of of you videos on baluns have provided much needed clarity. The SimSmith files you provided were also very helpful. (I spend a lot of time with them before things really clicked.) Please do not let the complexity of these topics deter you. You are providing an RF apprenticeship that is simply not available anywhere else. As you say many times, it would have been nice to have these tools many years ago. Yes, they help enormously, but the tools themselves are not enough. It takes someone with your insightful experience and gift for explaining and demonstrating them to really make the subject matter come to life. You are such a great teacher. Thank you, thank you, thank you! Dave NU8A

[@w0qe]

Dave, Thanks for the comments and glad you enjoyed this video. Feel free to comment anytime. Larry, W0QE

[@tomthompson6911]

Wow, Larry. This video covered a lot. It was very complicated, but covered some VERY interesting topics.

[@ErnestGWilsonII]

Thank you for making this video Larry! I am of course subscribed with notifications turned on and thumbs up! 73 W3GUY Side note on this video, it would be helpful if you could show some real world examples of how you use a balun in your antenna systems. Specifically how you combat common mode current and if using a balun causes any loss or other side effects besides combating the common mode current. It seems hard to believe that everyone wouldn't use a balun in every situation? Is there a performance or loss or some downside?

[@joes6718]

Larry, Thank you so much for this video. You answered many questions about antenna feedline configurations. When using baluns and matching networks. I could never find these answers in the past. Is there a link for the video files that you used?

[@w0qe]

Joe, Which video are you looking for the files for? Larry, W0QE

[@joes6718]

@@w0qe Larry, #82: Real Antenna Impedance, Maximum Balun Stress, and More

[@w0qe]

Joe, Send me an email address and I can zip the files for you. Larry

[@richarde735]

does it really make a difference where the choke resides? I have a 246’ windom design ocf (164/82) the is up at 85-90’ in my oak trees with 65’ of ladder line coming down to my 4:1 matching transformer / balun and it goes right in to the 1:1 choke balun (240-31 wrapped with 14ga teflon thhn with and offsetting 10 turn, 2 cond design).

[@w0qe]

Richard, Yes it does make a difference. Common mode current on the transmission line will partially get converted to differential current at both the antenna and the transmitter. Also the desired current to the antenna will partially get converted to common mode current if there is not a good balun to minimize this current. There is a lot more to this topic than is appropriate for a KZbin comment but I would want a balun at your 4:1 matching xfmr and another one very close to the transmitter. #31 material will work well over the HF range. Remember that winding a balun with 14ga. close spaced wire may be close but not the same as winding 50 ohm coax thru the #31 core. However since your OCF antenna operates with some modest SWR this may not make any practical difference. 73, Larry, W0QE

[@michaelst.angelo423]

@@w0qe Larry. Enjoyed your videos. I have a dipole fed with Ladder Line connected to a 4:1 balun and a common mode choke to a tuner. The tuner is connected to a rig via 50 feet of coax. Would you recommend chokes between the tuner and rig? 73 Mike N2MS

[@w0qe]

@@michaelst.angelo423 It's hard to say what to recommend but I would. The 4:1 balun may act as a common mode choke or not depending on what type it is. This is the place where a common mode choke would normally be place. Larry, W0QE