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  @SocietyBTWКүн бұрын

  Thanks for the help!

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  @lawrence1mdКүн бұрын

  Did you make your mini tripod?

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  @JimscoolstuffКүн бұрын

  Yes, I made the tripod. My design is now being produced by a company called Amratek Products, Amratek.com

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  @BrentLeVasseurКүн бұрын

  Hi Jim, have you ever made a tesla coil, where the secondary is bifilar wound where the EM field cancels out?

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  @JimscoolstuffКүн бұрын

  No, I have not.

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  @BrentLeVasseurКүн бұрын

  @@Jimscoolstuff I have a lot of questions I would like to ask you about tesla coils. Is there a way I can contact you? I’m a total noob and I don’t want to make any fatal mistakes. You seem to be an expert on the subject.

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  @JimscoolstuffКүн бұрын

  @@BrentLeVasseur Everything that I know about Tesla coils is shown in the video. Thanks for your comment.

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  @BrentLeVasseurКүн бұрын

  @@Jimscoolstuff How did you wind your coils?

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  @JimscoolstuffКүн бұрын

  @@BrentLeVasseur I have a metal lathe that I used to turn the coil form while I placed the wire by hand. It is actually much easier than it sounds.

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  @joygonzalez74573 күн бұрын

  My Faraday cloth just came in and with it arrived Faraday tape. I was pretty confused as to why the tape was sent, then I watched your video and you mentioned the fraying! That must be it. I used the tape as bias tape (double fold tape) and secured all the edges…no more worrying about fraying.

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  @Jimscoolstuff3 күн бұрын

  Thank you for this information.

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  @jbammi4 күн бұрын

  Jim, have you by any chance had a chance to play with the new 25 ft whip from Chameleon with the Amratek coil. With either the loading coil mode or in the matching network mode, i am having no luck getting a resonance point (using a rigexpert to sweep the band). Any advice appreciated.

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  @Jimscoolstuff3 күн бұрын

  It should work just fine if limit the length of the whip to 17.5 feet.

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  @jbammiКүн бұрын

  @@Jimscoolstuff Thanks Jim, yes i understand that, and 17.5 works just fine. My objective here is to have the maximum amount of metal in the air and the minimal amount of fake electrical length/coil, for max efficiency and widest bandwidth with a given SWR. Looks to me like the 30/40 coil does not have enough range to make this happen I was hoping that the matching network mode of the coil may be able to work, but i cannot find a resonant setting with that either. Are there any other possible configurations (like the 30 M one) that are possible that i could try. 73 de ws1m

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  @JimscoolstuffКүн бұрын

  @@jbammi The Amratek coils were designed to work with common 17 foot whips. 73

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  @jbammi23 сағат бұрын

  @@Jimscoolstuff Yes, the coil design is superior compared to the common stainless steel wire with a slider approach (ala Wolf River), and the non contact idea is brilliant. Perhaps the next version can be made with a little more range and does not end up as a "one trick pony" like this version. I was hoping the matching network mode may work, but that seems to have the same limited range. I'll experiment with some shunt capacitance to see if i can bring the system to resonance.

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  @Jimscoolstuff15 сағат бұрын

  @@jbammi The minimum inductance of the Amratek coil is 6.8 uHy. To resonate a 25 foot whip at 7 Mh requires an inductance of about 3.8 uHy. You could connect an inductor of 6 uHy in parallel with the coil, or you can remove several turns from the slider coil. Simulations with EZnec show that at resonance the input to the antenna will be about 16 ohms. this will give you a minimum SWR of about 3.1:1. I hope this helps.

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  @reedreamer95184 күн бұрын

  You quest is for naught. I already built the best magnetic loop antenna 5 years ago.

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  @theoview7 күн бұрын

  the big question Jim, when... is Part 3 arriving? You are a very valuable technician with expert knowledge! Could you share more about the coupling loop. Is this variable with the band choice? Turn an high Q loop into his own VFO... what type of LC oscillator is the VFO built? Thanks Jim Kind regards, 73 Theo. ( visually impaired radio amateur )

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  @Jimscoolstuff6 күн бұрын

  Thanks for your comment. I am busy with some other projects right now, but I intend to get back to the loop as soon as I can.

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  @justtinkering671310 күн бұрын

  I've made a couple of these through the years. The only problem is they are very noisy when the fabric pops back and forth. If you make it, locate it far away from your sleeping quarters

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  @Jimscoolstuff10 күн бұрын

  Thanks for this information.

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  @justtinkering67139 күн бұрын

  @@Jimscoolstuff Yeah, I'm an old guy too.

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  @N8ESP11 күн бұрын

  This video really resonated with me (pun intended) as I've noted the (strong) correlation between soil moisture and the performance of my ground-mounted trap vertical antenna. When conditions are dry, the antenna seems to benefit from additional ground radials and screen (I haven't tried Faraday cloth yet). When the ground is more moist, it doesn't seem to care as much about all my efforts (though my additional counterpoise efforts don't seem to detract). Of course, there's loads of variables in all this including general band conditions and man-made interference. With the long wavelengths involved with HF, the counterpoise for a vertical extends well past the distance where I have any ability to improve it (i.e. my neighbors, I'm sure, wouldn't be too keen about me installing radials on their property). I really enjoy your videos -- thank you for making them! 73 from N8ESP

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  @Jimscoolstuff11 күн бұрын

  Thanks for your nice comment.

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  @N8ESP11 күн бұрын

  Fantastic video! Thank you for sharing. I've been interested in Mag Loop antennas forever, but finally have the time to experiment with one. This video is incredibly helpful in that quest. Also -- the tuning method you created is absolutely genius!

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  @Jimscoolstuff11 күн бұрын

  Thanks for your comment. I am still working on my mag loop when time allows. I hope to do another video when it is complete.

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  @larrybushman112 күн бұрын

  Many thanks for that.

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  @Jimscoolstuff12 күн бұрын

  Thanks for your comment.

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  @justtinkering671312 күн бұрын

  I like the CD layers with the flexible flaps turbine. Shown on Robert Murray-Smiths channel.

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  @DominicMazoch13 күн бұрын

  Bobo Bear would tell Yogi Bear the in some parks Mr. Ranger would not allow a spike in the ground.

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  @Jimscoolstuff13 күн бұрын

  That is true in parks that are well manicured fields of grass. All of the parks near me also have wild areas. Thanks for your comment.

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  @DominicMazoch13 күн бұрын

  I use 3 30' tape measures and a double gator clip patch cables. Easy set up and tear down. And you can see the tape measure!

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  @Jimscoolstuff13 күн бұрын

  Thanks for sharing your idea.

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  @rkayakr20 күн бұрын

  Interesting innovation. I wonder how much loss there is in the inductive coupling? It would be good to measure this with a VNA like the nanoVNA.

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  @old-timeangler535621 күн бұрын

  Thank you, valuable information.

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  @Jimscoolstuff21 күн бұрын

  Thanks for your comment.

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  @found.ernest21 күн бұрын

  So basically just trim the flashing and tighten down on it?

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  @hiltopuk21 күн бұрын

  I learned about Faraday Fabric thanks, first time for me.

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  @dandypoint23 күн бұрын

  Did you calculate or measure what the capacitance value was on your foil/ rooftop capacitor? The reactance in ohms that you ended up with is really what I am wondering about. I am thinking if it was 15 ohms you would get the 1:1 SWR and as it goes down the SWR rises to the theoretical 1.42 at Xc =zero. If I did my math right Xc of 15 ohms is about 750 pf. So you would need about 1100 pf to get Xc down to 1 ohm. My numbers indicate if you had 12 inch square plate with dielectric K=2 and a spacing of 0.05 inches you would have about 1290 pf. I have no idea of the K value of car paint, but a K value of 2 seems to be conservative. I also think my 0.05 inch thickness is ultra conservative for car paint, but there may be a slight air gap below your plate so it could go either way. Your plate looks to be larger than 12 inches by 12 inches. So I am guessing your C is larger than 1200 pf.

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  @Jimscoolstuff23 күн бұрын

  I used a 2 foot long by 18 inch wide piece of aluminum foil. That is an area of 432 square inches. I did not calculate or measure the capacitance.

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  @dandypoint23 күн бұрын

  @@Jimscoolstuff thanks. That would give a very low reactance at 14 MHz for sure. I may try making some measurements on some of my mag mounts..

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  @w8lvradio23 күн бұрын

  Did you retune the coil after reach change to the counterpoise? 73 DE W8LV Bill

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  @Jimscoolstuff23 күн бұрын

  No I did not retune the coil. Apparently the resonant frequency of the coil and whip changed very little. Thanks for you comment.

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  @jluke686124 күн бұрын

  What a great Channel. Thank you.

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  @Jimscoolstuff24 күн бұрын

  Thanks for your nice comment.

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  @jluke686124 күн бұрын

  What a great Channel. Thank you.

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  @jluke686124 күн бұрын

  Thanks!

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  @Jimscoolstuff20 күн бұрын

  Thank you for your nice donation

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  @jluke686124 күн бұрын

  Thank you for taking the time and making this very great video. It takes a good man for that. You have another subscriber and a like.

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  @DaDitDa25 күн бұрын

  I assume your antenna is a base loaded 17ft or 18 ft vertical. If so, with a full ground plane, medium soil conductivity and tuned to resonance (at 3.7 mHz), the input impedance is about 8 ohms -- based on an EZNEC model. In other words, with medium soil conductivity, a relatively high SWR should be expected as counterpoise-to-ground coupling is increased (i.e., ground resistive loss decreased), and vice-versa as ground coupling is decreased (i.e., ground resistive loss increased). For poor soil conductivity, resistive ground loss will be high which will increase antenna input impedance and lower SWR. So, for your case, a high SWR indicates good ground conductivity and good counterpoise-to-ground coupling. And as you decrease counterpoise -to-ground coupling, you increase resistive loss and lower SWR.

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  @Jimscoolstuff25 күн бұрын

  Thanks for your comment.

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  @dandypoint25 күн бұрын

  Interesting video and results. I am convinced that the screen and radials capacity couple to the ground and the value of capacitance goes up with a larger screen and hence the capacitive reactance goes down with increasing area. That should be a good thing. I wonder if you did any measurements of real R and X values with the different areas. I am wondering if the real R value ( resistance at resonance ) changed with the increases size of the screen? That could maybe explain the SWR going up while the reactance was still going down. (I am going to watch the video again as I failed to note if the resonant frequency changed any). It has been my experience that the real R does change as well as the resonant frequency as I add radials. I have tried using the RBN ( reverse beacon network ) to detect signal strength differences but unless the difference is 10 dB or more the difference is hard to detect due to fading and other propagation changes. I have not yet had a good way to measure small field strength differences. I may try two identical mobile antennas as far apart as I can get them, one with minimum radials and one with increasing number of radials until I either see a difference or run out of wire! A big problem with two antennas connected to a normal coax switch is the grounds side of the coax is always connected together so I would need to physically disconnect the cable or use a DPDT switch. Again coupling between the two ground systems needs to be avoided in a test like that. Keep up the good work. 73, N4DJ

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  @Jimscoolstuff25 күн бұрын

  You are correct about the capacitive coupling to real ground. I demonstrate this in the video linked below. Thanks for your comment,

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  @vladtepes48125 күн бұрын

  You need to find the resonance frequency and impedance. This is where the reactance is zero and not where SWR is 1:1.

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  @danielzdanowicz689925 күн бұрын

  Wow! Very interesting data Jim! Thanks for doing the "grunt work" on this. One observation... where the two graph lines cross is a point of ground square footage that would seem to work with decent SWR for both wet and dry conditions. This analysis is certainly a good base line for further experimentation. Best 73s Dan K1YPB - On the air since 1962

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  @Jimscoolstuff25 күн бұрын

  You make a very interesting point. Thanks for your comment.

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  @larrywise587125 күн бұрын

  You might be changing the freq of the ant. A SWR sweep might give a little more insight.

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  @skepticwest962825 күн бұрын

  What is your definition of an SWR sweep? I thought I showed you SWR sweeps.

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  @DaDitDa25 күн бұрын

  What were the measured R and X values for the various counterpoise configurations?

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  @daveN2MXX25 күн бұрын

  A resonant vertical antenna is not 50 ohms, therefore a theoretical 1:1 match to a 50 ohm transceiver will not produce the most ideal radiation pattern. Your definition of "better" I guess means better SWR only, not better antenna peeformance.

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  @Jimscoolstuff25 күн бұрын

  A resonant vertical over a perfect ground has a resistive component of 37 ohms. Most modern radios have an internal tuner that can match up to a 3:1 SWR. Are you saying we should never push that tune button? The purpose of the video is to show that ground conditions can change.

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  @daveN2MXX25 күн бұрын

  ​@@Jimscoolstuff No... I am saying the exact opposite. Using lowest SWR to compare antennas or counterpoise systems is misleading and a mistake often made on social media and by ham youtube hobbyists. At 9:10 in your video you assert that from your SWR readings that it might make sense to "make the magic carpet smaller". I'm not sure how reduced ground coupling will improve vertical antenna performance in any scenario, regardless of incremental SWR changes.

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  @hughpatterson148025 күн бұрын

  Great video. I would have bet the ranch if someone asked whether or not enlarging your magic carpet improved your SWR. I'm going to try this out because now I'm extremely curious. Thanks again for an informative video...73...KN6KNB

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  @Jimscoolstuff25 күн бұрын

  Most of the time more is better. That is why I was so surprised at what I found.

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  @n0vty87325 күн бұрын

  I had a similar experience, my 1st thought was to put a choke at the base of the antenna. And the problem went away.

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  @Jimscoolstuff25 күн бұрын

  Thanks for your comment.

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  @Kangsteri25 күн бұрын

  It's not unexpected. If bad ground is comparable to jumping in a mud and full ground is comparable to jumping on concrete. Then tuned ground would be like jumping on trampoline.

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  @Jimscoolstuff25 күн бұрын

  Interesting analogy. Thanks for your comment..

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  @Kangsteri25 күн бұрын

  @@Jimscoolstuff Wish I could come up with something that smart :D Its stolen from a video called Understanding RF ground for antennas. I just tweaked it a bit.

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  @johnlagreca628826 күн бұрын

  Looks like you need to tune your carpet. Wrap it in a dowel and unroll to optimize.

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  @Jimscoolstuff25 күн бұрын

  Thanks for your idea.

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  @johnlagreca628826 күн бұрын

  I clicked 'like' 10 seconds in, subscribed at the end. Thanks for the data collection work, so much to further analyze. It would be really nifty if we could see the elevation and azimuth plots for these setups. I suppose it could be modeled but I am not too savvy at that... yet. In a pinch I have ran 32' of coax elevated to the vertical radiator with a common mode choke between the 32' section and the transmitter.

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  @oobihdahboobeeboppah26 күн бұрын

  Yeah, more counterpoises not better has been known for some time; diminishing return at some point. Rather than fretting over putting x number of wires out there, just put down one or two and get on the air. We always work stateside and DX using ten watts or less. Keep it simple and spend the time one the air.

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  @johnlagreca628825 күн бұрын

  Negligible return I believe, not diminishing. Unless you count effort and expense as the variable that subtracts from the return... and that is relative.

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  @glevideo26 күн бұрын

  I wonder how different bands affect the optimum square footage of the ground plane fabric.

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  @typohits821326 күн бұрын

  I don't think it is meaninful to try to evaluate the performance of an antenna by reference to the SWR alone. What you are interested in, is the radiation efficiency. The reason we add a counterpoise to the antenna is to increase the radiated field. It can be expected that adding more ground screen area to the vertical antenna system may cause the SWR to increase. If you had a 1/4 wave vertical, for instance, the radiation impedance is about 36 ohms, placing it over typical ground would have a ground resistance of about 16 ohms. These resistances appear in series, so you are burning up a good portion of your RF in the 16 ohms of ground resistance, but the SWR would be close to 1:1 because the total resistance seen by the transmitter is 52 ohms. As you improve the ground screen by adding radials, the ground losses will decrease, but the SWR will go up. If you continue to adjust the tuning of the antenna to provide an optimum match to the transmitter, the radiated field will be increased in spite of the fact the SWR is increasing. It is the field intensity we care about, not the SWR. Yes, many times, the SWR will improve as the field intensity goes up, but that is not necessarily the case and not likely in the case of ground-mounted verticals. A good reference is "Another Look At Reflections" by M. W. Maxwell, also "The Ground Mounted Short Vertical" by Jerry Sevick. A useful practical appreciation of antenna radiation and the function of counterpoises is in U.S. Army Technical Manual TM-11-666, which can be found as a download on the internet.

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  @johnlagreca628826 күн бұрын

  Sevick's paper is good stuff.

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  @lc79tourer2625 күн бұрын

  Absolutely correct, low swr does not mean greater efficiency, it only means a better impendence match to the transmitter.

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  @daveN2MXX25 күн бұрын

  This comment is 100% correct

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  @danielzdanowicz689925 күн бұрын

  At some point the ground plane size and its correlation to ground losses is affecting the return loss which seems to peak at a some magic point of correlation between all these variables. The greater the return losses the more chances of power being radiated.

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  @user-zk2yd6xm8s23 күн бұрын

  Get them every time. It's like saying a dummy load makes a great antenna. SWR is important but is not everything.

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  @brianinarizona435026 күн бұрын

  Hi Jim … Your productions are always interesting and I appreciate you taking the time to share them! Rookie question: Is it possible that the large wrenches that anchored the Faraday cloth might have an effect on SWR? I reckon you would have considered that so I’m primarily interested in why they don’t have an effect. Thanks again and 73.

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  @Jimscoolstuff25 күн бұрын

  Don't forget the cloth is a conductor so we have a conductor laying on a conductor which acts as one continuous conductor. I used to use rocks, but sometimes they are hard to find.

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  @brianinarizona435024 күн бұрын

  Thanks, Jim. I hesitated to use metal weights but I won’t on going.

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  @jerseyjeeper157526 күн бұрын

  Excellent information Jim 👍

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  @Jimscoolstuff25 күн бұрын

  Thanks for your comment.

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  @rolnas2126 күн бұрын

  Can you repeat without coax or very short?

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  @rolnas2126 күн бұрын

  Did coax have some chock balun? Your coax is also conterpoise if others are too small or missing.

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  @johnlagreca628826 күн бұрын

  Doesn't appear there is a 1:!. Jim did use one in some of the experiments he did last year.

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  @Jimscoolstuff25 күн бұрын

  No, I did not use a choke in either test.

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  @mikeramsey974727 күн бұрын

  Very informative

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  @Jimscoolstuff27 күн бұрын

  Thanks for your comment.

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  @mikeramsey974727 күн бұрын

  Jim, neat video on the various radials, your coils are very interesting and look a lot more efficient than Wolf River or Mad Dog coils.

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  @Jimscoolstuff27 күн бұрын

  Thanks for your comment.

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  @kennymanchesterАй бұрын

  I am ready to build one! Or perhaps modify my German made MLA from 1989 to get ride of the pushbutton tuning controller! You're right, the high-Q, 3-meter diameter 2in tubing design has a huge capacitor that requires quite a fine touch to tune. It's a beautiful example of German engineering. The AMA-3 was developed in 1983 by Christian Käferlein DK5CZ (SK) and it has withstoof the test of time very nicely. But, it could be improved. If you need any real assistance please let me know. I'll gladly help where I can. Kenny, NZ5i

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  @Jimscoolstuff29 күн бұрын

  Thanks for your comment and kind offer to help. At the present time I am working on another project, but I hope to get back to the mag loop soon.

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  @jerseyjeeper1575Ай бұрын

  I may have missed it, did you try 1/4y elevated radials with ground cloth? Great video! Thanks very much.

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  @Jimscoolstuff29 күн бұрын

  Yes we did at the quarry. We found that the ground cloth detuned the radials. I am working on another video about ground screens and elevated tuned radials. I hope to publish it soon.

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  @jerseyjeeper157529 күн бұрын

  @@Jimscoolstuff Thank you, appreciate the reply and will be watching. Also, I just ordered the full set from Amratek based on your videos. Order is on the way. :)

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  @ErnestGWilsonIIАй бұрын

  Thank you for making this video and sharing it with all of us! I am subscribed to the channel with notifications enabled and thumbs up! Question: Before you add any kind of coil, when you have the antenna whip acting as a quarter wave antenna fully extended to 17 feet and ground radials connected, what is the maximum power rating of that configuration? Reiterating and clarifying my question: When just using the quarter wave with the telescopic whip and any required radials, no coil connected, which is why my example would be 20 m through 6 m, what is the maximum power that that set up can handle?

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  @Jimscoolstuff29 күн бұрын

  That arrangement should be good for full legal power depending on the wire size of the radials and the coax voltage rating.

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  @ErnestGWilsonII29 күн бұрын

  @@Jimscoolstuff thank you for replying! What would it take to make one of those new style low loss coils that you have shown in your video to be made to handle 1500 W digital? Specifically on 40 m band. Could you scale one up to a size that would handle 40 m at full power without worry of overheating?

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  @Jimscoolstuff29 күн бұрын

  @@ErnestGWilsonII It could be done, but it would be expensive and I don't think very many would be sold.

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  @ErnestGWilsonII28 күн бұрын

  @@Jimscoolstuff I agree this is not a high demand item. How much do you think it would cost? Could you design one on paper? I just spent $1300 trying to solve this using a screwdriver antenna that claims 1500 W ICAS. In the end, I'm not looking for something that does 80 m at full power, but I am looking for an efficient coil that would bring me into the 40 m band at full power without heating up, so making something substantial would be required. 73. W3GUY.

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  @xtogarcia1463Ай бұрын

  Muy interesante.Este tipo de experimentos explican muchas paradojas y mitos extraños de la radioafición. Gracias por su tiempo, compartir e interés.

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  @shawncalderon4950Ай бұрын

  42:00 How to bulletproof the Slayer Tesla Coil?