Ape Answers 003: Baluns and UnUns
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- เผยแพร่เมื่อ 16 พ.ค. 2024
- Ape Answers is a short format video series where we answer Ham Radio related questions from viewers.
In this video, we cover some questions that were asked on my videos. Whether you're a beginner or an experienced user, we've got you covered with detailed explanations and solutions to common issues. Tune in to get your questions answered!
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The main thing is every new location we operate from has new noise to deal with and Apes instructions on how to mitigate noise is part of the ham program that we all signed up for.
It took me some figuring to get to that point. Thanks for watching Kevin 👍
Good job, Ape, I'm a big believer in using chokes wherever possible..
Me too. lol, thanks for watching BA 👍
A tutorial on toroidal, sizes, material types (#’s) would be very helpful
Hey Mark, I have a few comparison videos on this playlist: Learn about Chokes, Baluns and UnUns for Ham Radio Antennas
th-cam.com/play/PLm8ROkpFeqoqkGQtBYfcT9Y-2GCKxBuuk.html
❤love the videos I have a lot to learn and this is the right balance of technical knowledge and idiots guide.
Could you please bump your audio levels up a bit? I’ve got all my settings maxed and it’s still a little low
Glad you like the videos Matt. Thanks for the audio feedback 👍
All choked up
I heard someone singing that today
nice job. yes choke all cables. I even do my mic cable with one of them snap ferrites . i use USB cable on my 7300 so I got nice long one and wrap it threw FT 140-31 bunch of times. if that antenna feed line works out 450 ohm then 9:1 Balun. have to model antenna to get feed point ohms impedance. the off set center fed get confusing that not balance antenna but takes a balanced feed line. That why a Balun . feed line balance to un-balanced . so when looking at Balun and UNUN . you look at feed line in and out. some folded dipole work out 300 ohm . so a 4:1 gets close. when doing folded di pole the distance between the wires is part of impedance. like the folded dipole for FM radio is 300 OHM made out of twin lead. their is a double folded di pole type that is 450 ohm. for best with feed line loss is to get close to the feed line impedance as the antenna as possible. the trouble with window line is keep away from metal and try to keep it dry . 73's
Hey Robert, thanks for the info on the folded dipoles. Much appreciated 👍
@@TheSmokinApe read threw the ARRL antenna handbook. great source of info.
Nice job Ape! 73
Thanks Jeff 👍
Good lessons. Makes me wonder if arti-chokes are your favorite veggie, LOL.
I like them in a dip
Hi and thank you for all the great information. Question: if I want to build an antenna, how do I measure the impedance so that I can use the correct balun/unun?
Hey Marc, what I would do is build an antenna from well known design. THat would give you experience and know how and then you can experiment from there.
Interesting stuff Clarence! 😊
What I don't understand is why you used an LDG tuner with the 7300. Can it do 10:1 in lieu of 3:1 in the 7300 or something?
The LDG can tune to 10:1 👍
👍
Thanks for watching Hollywood 👍
You got questions? Ape has Manswers.
Haha, thanks Matt
Darwin was wrong: ape is the next step in human evolution lol
lol, thanks MTM 👍
I just started looking at folded TERMINATED dipoles. Those are different than plain folded dipoles, so, I can't help you. 🤷🏻♂️
Hey Lee, I’ve gone back and forth on the terminated dipoles, not sure I want to do it 👍
Hey SmkAp. You get less noise because you are killing your signals. You use lossy chokes, 1:1's, or whatever you can find to develop loss. Try reducing your radio RF gain. That way you don't lose transmit power.
I saw a video where you say that the common mode currents are not in addition to our desired signals, but by tuning (matching) the antenna to the transmission line, we maintain all currents as desirable currents rather than trying to attenuate portions of currents you feel we don't need. That's how I keep RF out of the shack.
I don't think you fully understand R +jX. R is the resistance of the antenna. All of it. Resistive and the radiation resistance. The X is the additive quantity of the antenna inductive reactance added algebraically to the antenna capacitive reactance. Circuit wise, you could take a resistor, capacitor and an inductor, all in series and your newly developed circuit will act like an antenna. Kinda. You won't have odd multiples. But at the resonance, your XL and Xc cancel and you have the R remaining. Right? Right. This is the electrical model of your antenna. Like your modelling program gives you the R+ jX value. You still with me? Makes sense? No. Because you don't know how to balance this series circuit. I don't believe in balanced and unbalanced circuits (Or antennas), so it doesn't bother me. But you are wondering about that. Why isn't the unbalancedness listed on the modeling program? Model an OCFD. It's not unbalanced.
It's great for this old RFI bus driver to be free of the shackles of old XYL's tales. 73. N9XR.
"I don't think you fully understand R +jX. R is the resistance of the antenna. All of it. Resistive and the radiation resistance. The X is the additive quantity of the antenna inductive reactance added algebraically to the antenna capacitive reactance. Circuit wise, you could take a resistor, capacitor and an inductor, all in series and your newly developed circuit will act like an antenna. Kinda. You won't have odd multiples. But at the resonance, your XL and Xc cancel and you have the R remaining. Right? Right. This is the electrical model of your antenna. Like your modelling program gives you the R+ jX value. You still with me? Makes sense? No. Because you don't know how to balance this series circuit. I don't believe in balanced and unbalanced circuits (Or antennas), so it doesn't bother me. But you are wondering about that. Why isn't the unbalancedness listed on the modeling program? Model an OCFD. It's not unbalanced. " I get that and appreciate the way you layout the topic. What I don't get is that you seem to think either CMC doesn't exist or isn't a problem.
@@TheSmokinApe
1. Common mode current depicts offsets from a non-resonant load. We know that ladderline doesn't radiate when the currents match and are of equal values with current going in the opposite direction measured instantaneously at an equal point along the line. So if we measure 2A going one direction at one point of the ladderline and 2A at the same point on the other lead of the ladderline, they cancel and the net sum is zero. No common mode currents. But if we measure 2A going one way and 1A going the opposite direction at the same point along the transmission line, we are seeing a common mode current of 1A. 2-1=1. It's not a current that exists on it's own doing it's own thing. It's a summation of 2 currents. Does it exist? Yes. Is it a problem? Yes.
2. There are several types of antennas. Many hams scream, "But the 5/8ths wave vertical isn't resonant and it works well". The 5/8ths vertical will have a matching network at the feedpoint of the antenna. Let's say a number for the feedpoint is (R +jX) 80 -j300. To make it "resonant", what do we need to do? We cancel out that -j300. That's an Xc of 300 ohms, so we need an inductor. Right. We need an inductor which is 300 ohms, and by golly, when you look at a 5/8 wavelength antenna, you will see an inductor at the base to do just that. So now our antenna now looks like 80 +j0. It's resonant. Yay, right? Well, yes, it's resonant, but are we happy with an R of 80? So manufacturers will tap that and make it an autoformer type device so it's 80 ohms to the vertical and 50 ohms to the coax. Now it's 50 +j0. It's what we can now call "matched". This is a step beyond "resonant".
3. That tapped coil in this instance does 2 things. A) transforms 50 ohms to the antenna's 80 ohms, and B) cancels the Xc of 300 ohms. Is there loss in this coil? Sure there is. But I needed it to get the antenna "matched" and I may lose 1 dB to gain several dB from not having a matched load. It's a good trade off. It's measurable.
4. Look at 1:1's and whatever you want to call them. Do they transform impedances? No. Do they cancel reactances? No. What do they do? They provide a loss that helps improve SWR for the sake of improving SWR. It's just like throwing resistors into the mix and let the losses take over. Do we have to calculate transformation ratio's? No. Do we have to measure uncancelled reactances? No. It's really just "Matching for dummies". We do this because as an Elmer, we don't have to explain anything. It's a lossy way to get things done.
5. We have forward currents, we have reflected currents and we have currents dissipated along the way, either as radiated waves or dissipation in ohmic losses. There are no "common mode currents" which magically ride on the outside of the coax. I explained that in 1. This is engineering 101. Walt Maxwell suggested this crap to make his job easier and to sell 1:1 baluns. He knew better, he was just a scammer and people bought it.
I doubt you will read this or try to understand. I don't know why I waste my time with mere mortals.
Jerry, unequivocally I spend more time reading your comments than anyone else’s 🍻I do appreciate them
@@TheSmokinApe think about it. The R +jX is electrically the same as a resistor in series with the inductor in series with a capacitor. Therefore we have a series resonate circuit. There are 2 opposing current laws which disagree with each other. I prefer Kirchoff's current law. It says the current is constant throughout the series circuit. When resonate, there's no common mode current. The opposing current law, (I can't remember the name of that one but ham influencers rely on it) says that the current will not be constant. It says that some of the current is jerked off of the antenna and placed precariously on the outside of the shield of the coax. What's the name of that law? I can't remember. I'm old now. I retired from bus driving yesterday. Maybe you would know. I don't do that law anyway. N9XR, formerly known as the bus driver.
@@BusDriverRFI Common mode currents exist and can be measured. The don't rely on a person's faith that they don't exist and don't respond to opinion. They are very easy to measure and it uses the same technology in most modern SWR meters. Here's a how-to to build one. The work very much like clamp-on meters for measuring current in AC power circuits. Do an internet search for "owen duffy common mode" and he will teach you how to build this very simple device.