HOW TO CONNECT SMALL LOOP: The inner wire of the coax RG58 is connected to one end of the small loop and the shielding is connected to a second end of the small loop. 73 Paul OM0ET
Hi there. Its George in the UK. I have watched many UA-camrs videos regarding magnetic loop aerials. I have found your videos to be the most informative. I have just completed making one using mainly scrap material and Car Brake pipes. It receives very well. Not tried transmitting as only just purchased a transceiver. My loop is 1metre in diameter with 300mm for smaller loop. Ex military tuning cap 200pf. Will do a video soon. Best wishes from old George and Jane 👍🇬🇧👫🤠
@@OM0ET My mag loop is complete. Great on receiving. However I have given up trying to get the swr below 3. I Don't have an analyser. Tried small loop closer or farther away from main loop. The main capacitor peaks ok on receiving stations. I have put in parallel to main capacitor a 50pf tuning cap. As a fine adjustment. Set to half capacitance. Then peak receive on main cap. Then vary fine cap to set peak accurately. I am working blind without an analzer. Cheers from old George
Great video. Thanks for posting. I have been thinking about the xiegu radio lately . Do you find the built in swr band graph to be especially helpful ? I as thinking it might allow me to dispense with bringing my swr meter on an outing. Thanks again .
I may be totally off here, but looking at the inside of the box, it looks like the capacitor is connected (via the red+blue wires) to the center-connector of the big outer loop ? Doesn't the coaxial shielding of the outer loop prevent any radiation from escaping the center-lead ?
OM0ET many thank's I will try to made one of your mag loop . But much long for also the 40 mtrs . I hope doing a qso with you on the air à day .. I am qrp'er but on cw mode . 73 and many thank's again . 👍📡
Are there instructions for assembly? You information suggested very critical tolerances. I am not sure that I could assemble the antenna. Am I correct that my antenna lead connects to the small loop? Thank you for your for your time and help in advance. Tommy
I'm not sure I understand the construction of the antenna and the choice to use the inner conducter and not the shield, which it seems would present much more surface area considering the skin effect of rf on a conducter.
I had that same thought. ANd not to mention that the shielding would prevent radiation from the center lead to actually escape. I might be totally off, but figured the shielding would work as a faraday cage thus preventing radiation escaping that coaxial. I am sure the antenna works -- so I must be mistaking, but I would like to know what I don't understand here :)
I built the same antenna, but i did not interrupt shielding of the coaxial cable of the main loop on the highest point (as you did in your drawing). But it works for some reason... how is that possible?
Thank you for very interesting video. I am a newbie to SWL and would like to build this. A couple of questions if you would. Would this work in my loft, is the layout the same for just RX. I have air capacitors in junk box. Would I need to use my homemade antenna tuner for this, or would it help. Hope the questions are not too daft. I am OK on making and soldering but not too bright with theory. Thanks again for video.
Hello Mike. You can use any air variable capacitor what you have, but it have to be with higher capacity, at least 300-500pF. Magnetic loop antenna when are properly build doesn't need any aditional tuner because when you tune this antenna on desired frequency , you should get 1.1 SWR. But if you are only SWL so you don't need worry about SWR on your magloop antenna :) If you would like to use your magloop remotly on in your loft you should find solution how to tune this antenna remotly from your room, because this type of antennas is very very narrowband and requires tune very often ;) 73, Paul.
@@OM0ET Thanks for that Paul, the tuning bit completely slipped my mind altogether, so I will have to rack my brains for that one. I have a large enough air capacitor for the job. Very interesting, thanks again.
Tha k youfor sharing your super neat work!!! I really like it. 2 things I'm not agree, in order to reduce the resistivity along radiator BOTH shield and center conductors MUST be connected. An electrical "short" is needed. The shield soldered to the center conductor. 2) when you are using a 2 gangs air variable capacitors in series the total capacitance is the inverse of each capacitor. For example 1/340pF+ 1/380pF.
Сергей Усманов hi Sergey. I tryed both versions and this with only center connected is much more better SWR and not so sensitive to nearby objects. With connected shielding is very little stronger radiating of this antenna. So my choice was the first one without shield connected. 😉
Hehehe... Every dB of an emitting signal is a hundred kilometers far correspondent you can reach. I will try to use both the central wire and shield soldered together - this should affect the common conductivity and, therefore, the performance of the antenna. I guess so.
OK, I see, thank you! I too will use the inner wire only - this approach of attaching the connectors seems to be even much easier (for further disassembly).
Hi I'm new to the loop antenna when you talk about the outer shrild not being connected do you create a split in the outer sheild of the coax at the top of the outer loop or is the break created at the pl259 ends Thanks in advance
Dear friend, the sections of the variable capacitor connected in such a way are connected in series and do not have a capacity of 700 pF, only a maximum of 174 pF, but a higher breakdown voltage is obtained. What max power can be applied in your antenna so that there is no sparking on the capacitor? Regards, Marek SP2CG
@@OM0ET even better. Would be very interested in one if you ever felt like making another 😉 if you do give me a shout paul cheers scottdobinson@yahoo 👍
Hi Paul, some time ago I built my own loop. It is 1.2m D / 23cm d excitation loop and double gang 300pf capacitor. I did not use it so much till now after I add a stepper motor to tune (manual). I'm using mcHF rig. On 20m it looks fine, but on 40m I noted some strange behaviour: some time it looks like no power is emitted even if it is tuned (2nd checked with VNA). Speaking on mike, the rig power meter show very low power and SWR is 0 then suddenly power increase as well SWR (correlate to my voice). I check modulation level with dummy load and seems good. Any suggestion ? (I'm a digital guys :) ). 73 iu2omt Paolo
Hi Paolo. I think you have shorted capacitor and in one position will apear spark between the plates. It's just my guess, I am not sure of course. Best 73! 😉
It's not a max limit, but your capacitor may be broken. Try to use compressed air to blow dust away from the space between the capacitor plates. It may help
![40M UltraLight QRP magnetic loop antenna + TEST [ XIEGU X5105 ]](http://i.ytimg.com/vi/dcs5srMJamE/mqdefault.jpg)
![40M UltraLight QRP magnetic loop antenna + TEST [ XIEGU X5105 ]](/img/tr.png)
HOW TO CONNECT SMALL LOOP: The inner wire of the coax RG58 is connected to one end of the small loop and the shielding is connected to a second end of the small loop. 73 Paul OM0ET
I can't believe how wide the dip is on the graph. That's amazing for a loop.
It seems to be about 20kHz wide on 20M band.
Hi there. Its George in the UK. I have watched many UA-camrs videos regarding magnetic loop aerials. I have found your videos to be the most informative. I have just completed making one using mainly scrap material and Car Brake pipes. It receives very well. Not tried transmitting as only just purchased a transceiver. My loop is 1metre in diameter with 300mm for smaller loop. Ex military tuning cap 200pf. Will do a video soon. Best wishes from old George and Jane 👍🇬🇧👫🤠
Thanks George! I wish you good luck with your own Magloop antenna and many nice contacts! 😉👍
@@OM0ET My mag loop is complete. Great on receiving. However I have given up trying to get the swr below 3. I Don't have an analyser. Tried small loop closer or farther away from main loop. The main capacitor peaks ok on receiving stations. I have put in parallel to main capacitor a 50pf tuning cap. As a fine adjustment. Set to half capacitance. Then peak receive on main cap. Then vary fine cap to set peak accurately. I am working blind without an analzer. Cheers from old George
Thanks for sharing your knowledge
Thank you! There is also a link to my website with more pictures and info. ;-) 73
As always a very descriptive and concise video. 73 de KE2YK
Молодец. Хорошая конструкция. Сам делал подобные, но на диапазон 160, 80 и 40 метров. Удачи, 73!
Спасибо! Хорошего дня ;-) 73
А какие размеры кольца и петли должны быть на 80 и 40 м?
I like your tutorials and videos
Thank you for sharing your knowledge
Great video, thank so much🙏
Very nice work. Bravo
Robybz thank you very much! 😊
Excellently, thank's!
very well explained. Thank you.
Great, thanks
Great video. Thanks for posting. I have been thinking about the xiegu radio lately . Do you find the built in swr band graph to be especially helpful ? I as thinking it might allow me to dispense with bringing my swr meter on an outing. Thanks again .
X5105 is my best qrp radio I ever had. SWR graph is very very helpful to me. Thanks for watching! 😉👍73
You only use the inner conductors of the loop part?? What about the shielding?
I may be totally off here, but looking at the inside of the box, it looks like the capacitor is connected (via the red+blue wires) to the center-connector of the big outer loop ? Doesn't the coaxial shielding of the outer loop prevent any radiation from escaping the center-lead ?
Won't it work better if you connect the tuning capacitor to the outside of the coax on the loop or doesn't it matter?
many thank's for your instructive video but I don't understood at 7:50 mns
How long must doing to " cut " the ground line please ?
The gap should be at least 3-4 cm. Place without shielding.
OM0ET many thank's I will try to made one of your mag loop
. But much long for also the 40 mtrs . I hope doing a qso with you on the air à day .. I am qrp'er but on cw mode .
73 and many thank's again .
👍📡
I wish you good luck with your own MLA! And on 40m the efficiency is not very usable with this diameter. 73 and thanks for watching!
Is it possible with the Loop
to receive the 49m band? 73
Are there instructions for assembly? You information suggested very critical tolerances. I am not sure that I could assemble the antenna. Am I correct that my antenna lead connects to the small loop? Thank you for your for your time and help in advance. Tommy
Sorry where can I find previous version
Thank You for such a great detail video. Could you possibly give the length of the conductors of the outer and inner rings?
Thank you. Please visit my website in video description for more info. 😉👍 73 Paul
*Здравствуйте! Не могу разобраться в вашем почерке! Петля связи меньше на 1/5 или на 1/3?*
do you have a mag loop that will work on 40-10m?
I'm not sure I understand the construction of the antenna and the choice to use the inner conducter and not the shield, which it seems would present much more surface area considering the skin effect of rf on a conducter.
I had that same thought. ANd not to mention that the shielding would prevent radiation from the center lead to actually escape. I might be totally off, but figured the shielding would work as a faraday cage thus preventing radiation escaping that coaxial. I am sure the antenna works -- so I must be mistaking, but I would like to know what I don't understand here :)
Well, you probably forgot that there is also quite a big capacitance and coupling effect between center core and the shield 😉
@@OM0ETI am going to try this, I have some LMR400 here and would like a qrp loop for my FT817.
Hello Paul!!! Could you tell me what is the diameter in centimeters of the Main Loop and also of the Coupling Loop, thank you in advance Paul 73
Подскажите пожалуйста , где продаются КПЕ UNITRA ?
I built the same antenna, but i did not interrupt shielding of the coaxial cable of the main loop on the highest point (as you did in your drawing). But it works for some reason... how is that possible?
What is the lenght of shield gap in the main loop? Thanks
This gap is no longer required. Just leave the shield normally in one piece and antenna will work OK also 😉👍 In v.4 I dont use the gap any more.
@@OM0ET very interesting. Tnx Paul.
@@OM0ET are you always use only the center core of the H1000 leaving shield open?
@@vannidifede9492 Yes :) It works good
I don't understand the 700pF value. Two capacitor in serie should give around 170pF not 700pf?
Yes that's correct. In the video is a fault. Sorry! 73 Paul
Parallel
Thank you for very interesting video. I am a newbie to SWL and would like to build this. A couple of questions if you would. Would this work in my loft, is the layout the same for just RX. I have air capacitors in junk box. Would I need to use my homemade antenna tuner for this, or would it help. Hope the questions are not too daft. I am OK on making and soldering but not too bright with theory. Thanks again for video.
Hello Mike. You can use any air variable capacitor what you have, but it have to be with higher capacity, at least 300-500pF. Magnetic loop antenna when are properly build doesn't need any aditional tuner because when you tune this antenna on desired frequency , you should get 1.1 SWR. But if you are only SWL so you don't need worry about SWR on your magloop antenna :) If you would like to use your magloop remotly on in your loft you should find solution how to tune this antenna remotly from your room, because this type of antennas is very very narrowband and requires tune very often ;) 73, Paul.
@@OM0ET Thanks for that Paul, the tuning bit completely slipped my mind altogether, so I will have to rack my brains for that one. I have a large enough air capacitor for the job. Very interesting, thanks again.
@@mikepeirson1150 you're welcome my friend! If you have some questions write me in our facebook group "QRP World" 😉👍
73 and good luck!
Very NICE Paul . More Information Lenght of Coupler Loop and Main Loop Best 73
Tha k youfor sharing your super neat work!!! I really like it.
2 things I'm not agree, in order to reduce the resistivity along radiator BOTH shield and center conductors MUST be connected. An electrical "short" is needed. The shield soldered to the center conductor.
2) when you are using a 2 gangs air variable capacitors in series the total capacitance is the inverse of each capacitor.
For example 1/340pF+ 1/380pF.
Es 1/c = 1/c1 + 1/c2
179.44 pf
Hi! Why didn't you connect the central wire and shield together? Perhaps, this could bring some interesting result. 73! UT8UU.
Сергей Усманов hi Sergey. I tryed both versions and this with only center connected is much more better SWR and not so sensitive to nearby objects. With connected shielding is very little stronger radiating of this antenna. So my choice was the first one without shield connected. 😉
Hehehe... Every dB of an emitting signal is a hundred kilometers far correspondent you can reach. I will try to use both the central wire and shield soldered together - this should affect the common conductivity and, therefore, the performance of the antenna. I guess so.
I measured the outer signal strenght by both versions and there was almost not recongnizable difference.
OK, I see, thank you! I too will use the inner wire only - this approach of attaching the connectors seems to be even much easier (for further disassembly).
Hi I'm new to the loop antenna when you talk about the outer shrild not being connected do you create a split in the outer sheild of the coax at the top of the outer loop or is the break created at the pl259 ends
Thanks in advance
Hi Sean. No the outer shield is not connected to anything. I use only inner line connected to capacitor. It's slightly different design like others 😉
@@OM0ET Oh I see thanks for responding
Dear friend, the sections of the variable capacitor connected in such a way are connected in series and do not have a capacity of 700 pF, only a maximum of 174 pF, but a higher breakdown voltage is obtained. What max power can be applied in your antenna so that there is no sparking on the capacitor? Regards, Marek SP2CG
Yes, you are correct, but I did mistake in the video
Hola me gustaria que hicietas el comentario de la antena loop enespsñol que no meentero de nada
SEBAGEY Very Good!!!
Dear Sir,how about the 7 mhz,diameter size for the main loop and small loop ??... thanks
Hello. You have to find my another video with ver.4 antenna 😉
Are they safe to use? Is rf dangerous
It's just a 5W, I think it's the same power like cellphones, but on much lower frequencies. I don't think so...actually I am not sure.
Nice work paul. For sale or also hit with copyrights 🙈🙈 i have to ask 😉 m6osd
LoL this is my design 😃 no copyrights hihi
@@OM0ET even better. Would be very interested in one if you ever felt like making another 😉 if you do give me a shout paul cheers scottdobinson@yahoo 👍
m6osd scott & OM0ET Agreed shame to waste all the Cap box lables 👍🏼
I believe LMR-400 coax is equivalent to the Nordix MWC 10/50.
Yes 100%
言語はわからないけど、回路図は世界共通なので理解できます。ありがとう
3:30 - the nut on the right connector is skewed. Good luck!
Oh yes, I found it after recording this video 😄👍 tnx!
Yep, cross-threaded.
Hi Paul, some time ago I built my own loop. It is 1.2m D / 23cm d excitation loop and double gang 300pf capacitor. I did not use it so much till now after I add a stepper motor to tune (manual). I'm using mcHF rig. On 20m it looks fine, but on 40m I noted some strange behaviour: some time it looks like no power is emitted even if it is tuned (2nd checked with VNA). Speaking on mike, the rig power meter show very low power and SWR is 0 then suddenly power increase as well SWR (correlate to my voice). I check modulation level with dummy load and seems good. Any suggestion ? (I'm a digital guys :) ). 73 iu2omt Paolo
Hi Paolo. I think you have shorted capacitor and in one position will apear spark between the plates. It's just my guess, I am not sure of course. Best 73! 😉
@@OM0ET thanks, capacitor is like the one you are using for your loop.
rig power is 8w. Is it at the near max limit? 73
It's not a max limit, but your capacitor may be broken. Try to use compressed air to blow dust away from the space between the capacitor plates. It may help
@@OM0ET thanks, will try it
Super sieht aus wie gekauft.Gut erklärt. Werde ich nachbauen.🖕
80м D-?
Какой кабель применяли
catalog.belden.com/techdata/EN/H1000C1_techdata.pdf
Schaut euch mal die Mutter oben rechts an.Das sieht aus als ob sie verkantet auf dem Gewinde aufgeschraubt ist.