HAM RADIO: 40M Spiral Magnetic Loop Antenna. Build a Loop antenna
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- Опубліковано 20 сер 2024
- HAM RADIO: 40M Spiral Magnetic Loop Antenna. Build a Loop antenna. I have already built a Spiral loop antenna for the 80M band that works brilliantly so I thought the time was right to try one for 40M, In this video I do just that build a spiral loop for the 40M band.
Franks Website:
www.nonstopsys...
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Cheers
Mike - M0MSN
P.S. do not take my word for it, give it a go for yourself.
![40M UltraLight QRP magnetic loop antenna + TEST [ XIEGU X5105 ]](/img/n.gif)
Well done, a nice tidy job. FWIW a colleague and I built a similar structure but varicap tuned for receive only, pretty spectacular performance. Solvent adhesive is wonderful stuff too,
Having recently moved into a flat, this could be just what I need to get onto 40M. Many thanks, G7MJV - Salisbury
Nice build Mike. I would of never thought of using a six pack of water bottles as a base. You Brits are so clever. Brilliant !! 73 Joe
Thank you! Cheers!
I hear that in England the water drains down the other side of the sink... BTW, I just noticed at the end, you bear a striking resemblance to Tony Iommi of Black Sabbath...
I made the 20M and 40M version but as I dont have a cap small enough I made a gimick cap but u NEED a choke at the feed point,theres also a spiral dipole which works even better
I've been waiting for your 40m loop. I'm going to build one.
Go for it, It is not as good as the 80M version but it works. :)
@@mike-M0MSN I already built a 20-10 loop but want one for 40 meters. Wondering how many watts you can run on your 40m loop?
That is a really awesome build! Thanks for sharing with us!
Amazing, I watched the video were callum was over and checking out that capacitor you made. Absolutely brilliant Mike some engineering went into that.
I am using a Paul koshaolin (Poland) cobweb antenna for 20-10. I have a really small garden in a communal area and am severely restricted so these compromise type of antennas I have to make do with.
One day I will build a loop for the loft I think.
Cheers again Mike thanks for sharing
Rab de MM7BVP
Very neat build. Thanks for sharing Mike.
Thanks for watching!
Everyone asking him self if this will work in 160 meter band (or efen 180 meter band) can do some thinking over himself. Btw. The 25pF trimmer replaced by a 220pF brings a 80 meter band version as low as 1380 khz. Also, if you look at what happens from 40 meter band measures to 80 meter band with the measures you notice 40 meter is 0,65 factor (the 57 cm goes to the new 89 cm length in the 80 meter version and 57:89 makes a 0,65 factor) The new length is 138 cm for 160 meter band (89:138=0.65), with turnable capacitor lets say 65 pF you should get the antenna efen as low as 180 meter band. I am making a 160 meter band version and hopes it will work, still in experimental stadium. Do as me and constantly look what changes from 20 to 40 to 80 metres and you find out how to make a 160 metres spiral loop. Correct me if am wrong
Nice neat build !
Nice going, Mike.
Nice build Mike, thanks!
Thanks 👍
Excellent video, an enjoyable watch Mike. Mark, 2E0MSR
Many thanks!
Great build Mike, I would have liked to see the connection to the antenna and capacitor .
Take a look at the 80 metre version
Very cool! Thanks for the video!
Glad you liked it!
Nice Mike, i might try this.
Please do!
Top Work Mike. 🙂
Thank you! Cheers!
Well done Mike, your workmanship is excellent and of course your video presentation is relaxing and easy to follow. Wonder if you cal have ever thought about a video comparing your loop to cals vertical !
I don't ever remember seeing a video like that before, just a idea. 73 zl3xdj
Great suggestion!
Brilliant video..would love to have a go at one of these...any details on your capacitor?
In the next video... about a weeks time
Nice video. I hope it gives you tons of DX and fun! 73
I hope so too!
Nice job, Mike. I quite like this antenna design. Hoping the TX results are as good as the 80 meter version.....don't see any reason why it wouldn't be. Are you printing the capacitor parts with PLA?
Enjoyed the video; good, high quality build. Especially the variable capacitor. Noticed at the end that you had your attenuator on on the Kenwood. You'll probably have better SNR with the preamp engaged and the attenuator off.
Rarely (never) is a pre-amp required on 40m, and pre-amps amplify the noise and the signal - they don’t improve SNR. Most people who work 40m a lot use attenuation on 40m and adjust the gain so signals are just a bit louder than the noise level. Pre-amps are typically only needed on 15, 10 and 6m- and only if there isn’t noise. There is a reason for attenuators, and he’s using it properly.
@@kd8opi all of what you said is entirely accurate, except for the fact that he’s using an unamplified magnetic loop-where using a preamp (and not an attenuator) makes perfect sense. You are losing dynamic range by driving a passive loop’s small signal beneath the noise floor of your rig. Remember that he’s about 20db down on receive (when properly tuned) from a dipole or loop. Adding an attenuator to that means that he’s about 30db down in total. In an ITU rural situation, that would imply a -140dbm noise floor. The TS-990 sensitivity is about -125dbm without the attenuator on, and about -115dbm with it on. Does that make sense?
@@philjensen5151 Um, no. For simple reasons. Look at his s-meter. He’s nowhere near a a -125 dbm noise floor, he’s at S3 noise WITH the attenuator on, probably S5 or worse with it off. That’s the problem with using ideal numbers in terms of receiving sensitivity. They essentially do not reflect reality, and represent theoretical lab generated data. I would might with you if his S-meter read 0-1, but it doesn’t. His noise floor is probably around -90 dbm, and he’s nowhere close to driving his rig beneath his noise floor.
@@kd8opi I'd have a hard time making the assumptions that you are making without putting the antenna on a spectrum analyzer, or one with a calibrated signal meter. I use an Icom R-8600 to make my measurements (or an RTSA). I wouldn't put money on the 990's S-meter being anywhere remotely linear below -100dbm, but that's just me. 73 de N4PAJ.
@@philjensen5151 The thing is Phil, if you look at the 990’s manual, they’re pretty insistent that their S9 level is -81dbm, and their S3 on 40 meters translates 100 dbm. As buggy as it is, its the only meter we have on his noise floor. Attenuation can be anywhere between 6 and 18 dbm. . He may be looking at a “true” noise floor of -94 dbm, with only 6 dbm (S5), or as high S9 with 18 dbm attenuation. Conversely, turning on his pre-amp gives you 6-18 dbm of amplification. I just done see how his S/N ratio can improve by pre-amping his background noise anywhere between s5 and s8. There just isn’t that much dynamic range left at that point. He just isn’t anywhere near the theoretical noise floor of his receiver. Almost nobody is on 40m, and it’s why pre-amps are almost universally discouraged on 40, 80, and 160 (even 20m is iffy). God forbid you have a thunderstorm w/in 300 miles, the crashes would be unbearable.
Good Job!
Thanks!
If you're doing this in your kitchen.... there's no way you're married!
Awesome design. I may even try this. Have you managed any Dx contacts?
Best regards
Andre (ZS6ALH)
Sunny South Africa
Lovely build. Have you thought of building 4 and changing the phase to make directional?
Hi Ian thank you , and nice idea...
Mike, remind us again where you’re getting the capacitor from. I want to say your building then yourself, but I don’t recall for certain.
This looks great. Is there a reason the spacing needs to be "precise" or can I just put the wire 6" apart and call it good?
Like all loops this is an inductor and the spacing helps calculate the loops inductance and so the needed capacitor, ;)
THE link does not work to get the details . any one have it ?
That looks great! But where do I get the parts to build a capacitor?
Is the capacitor a kit or did you build it?
Ok
Hi Mike, compared to a common magnetic loop (1 turn) of the same size, which do you think has better performance?
Will an antenna tuner work in lieu of the capacitor?
No Idea Pat, but I would say yes.
👍👍
How many Watts will your design handle?
Can this be made multi band??
yes ish
great video!! is this a receive only loop or will it work well on transmit as well?
Both I have to test it properly but if the 80m one is anything to go by......
What was the link to the site you are referencing?
0:55
www.nonstopsystems.com/radio/antennas_home.htm
Thank you!
Can we use it for the transmission ?
yes you can
@@mike-M0MSN Thanks dear..
How thick are the capacitor spacers ?
5mm spacers 1mm plates 2mm between each plate
Thanks Mike
will it work for tx 100 W? of only receive ?
De HZ1YA