I want to try this next because I built me a 49:1 for my EFHW Antenna but the only thing I dont like about it is I am more limited with this set up with it being a half wave set up. I say this way is best if I am trying to accomplish an end-fed antenna for one band maybe 2.....but the random wire setup via a 9:1 I think is more what I need so Imma get to wrapping and do exactly what you have shown in this video and see the results I get. AWESOME VIDEO BRO....AWESOME VIDEO!
Basically the circuit design would be the same. For low power operation, you can use a smaller coil (1.5"), smaller gauge wire (16ga), and variable air capacitors with a lower voltage rating (100 to 200 volts). For QRP applications, the air gap between the plates would be much smaller so the form factor of the variable capacitors are much smaller. See hyperlink (this is good for 100 watts): www.ebay.com/itm/Capacitor-365pF-Variable-Single-Section/132032487083?epid=1712229709&hash=item1ebdbfdeab:g:N2wAAOSwfSJdC88J
i built it like in the drawing 9:1 open core 2" former, 2.5 mm wire(copper) plastic coated 3 mm thickness total 12 turns, the what i find on antenna analyser is interesting , 50 to 100 ohm so.. basically 1:2 on a fiberglass former,, what? he he,,, yeah. so i added taps on the center wire for more ratios. will play more when i have time. the small junkbox toroids i have yields better results but albeit Micky mouse power :) so i must have a 144 ohm 2ndry, but alas closer to 100 to 120 ohm... remember mine is 12 turns not 9 for those interested
Great series of Videos, RF Man . Thank you. Am I correct in thinking that it's the triple wire turns (tri-filar winding ?) that gives the 9:1 ratio (ie 3-squared) NOT the actual 9-turns ? That's just coincidental ! So for 16:1 you'd use 4-cores but maybe still only 9 turns ? Could more turns be wound on a bigger toroid - or even on an air-spaced former - or less on a smaller, and still get the same ratio ? I appreciate that air spaced will have totally different permeability than ferrite based formers and give different results, but conceptually it's still a sound alternative ?
Good video. One question, could you explain how to build for different power requirments and which gage wire and which toriod is needed. Does a #6 material work as well as the 43?
I noted strange behavior with MFJ1984MP vs power level - 5watt low swr - 25w and higher, HI SWR at the same frequency. 40 M band. It is supposed to handle 300w PEP
Remember, power rating in any balun is into a matched load. In this case with your 9:1 would handle about 500 watts from a single core into a 450 ohm load. As you stray away from 450 ohms, the power rating goes down !
So if your antenna is 900 ohms, then why not make an unun with 1:4 turns. Giving you an z transfer of 16. 16x50 = 800. Swr capable of 900/800 = 1.13 ???
But the impedance of that "long wire" as you call it, isn't going to be 450 ohms on every band and or frequency! Impedances can change greatly as frequency changes!
I want to try this next because I built me a 49:1 for my EFHW Antenna but the only thing I dont like about it is I am more limited with this set up with it being a half wave set up. I say this way is best if I am trying to accomplish an end-fed antenna for one band maybe 2.....but the random wire setup via a 9:1 I think is more what I need so Imma get to wrapping and do exactly what you have shown in this video and see the results I get. AWESOME VIDEO BRO....AWESOME VIDEO!
Interesting. Would be nice to see a vidio on building them for different power requirements.
Basically the circuit design would be the same. For low power operation, you can use a smaller coil (1.5"), smaller gauge wire (16ga), and variable air capacitors with a lower voltage rating (100 to 200 volts). For QRP applications, the air gap between the plates would be much smaller so the form factor of the variable capacitors are much smaller. See hyperlink (this is good for 100 watts): www.ebay.com/itm/Capacitor-365pF-Variable-Single-Section/132032487083?epid=1712229709&hash=item1ebdbfdeab:g:N2wAAOSwfSJdC88J
Well explained, thank you.
Is there a way you can make your presentation slides downloadable?
i built it like in the drawing 9:1 open core 2" former, 2.5 mm wire(copper) plastic coated 3 mm thickness total 12 turns, the what i find on antenna analyser is interesting , 50 to 100 ohm so.. basically 1:2 on a fiberglass former,, what? he he,,, yeah. so i added taps on the center wire for more ratios. will play more when i have time.
the small junkbox toroids i have yields better results but albeit Micky mouse power :)
so i must have a 144 ohm 2ndry, but alas closer to 100 to 120 ohm...
remember mine is 12 turns not 9 for those interested
The unun with core material 2 appears to have 10 turns on the core, not 9.
Great series of Videos, RF Man . Thank you.
Am I correct in thinking that it's the triple wire turns (tri-filar winding ?) that gives the 9:1 ratio (ie 3-squared) NOT the actual 9-turns ? That's just coincidental ! So for 16:1 you'd use 4-cores but maybe still only 9 turns ? Could more turns be wound on a bigger toroid - or even on an air-spaced former - or less on a smaller, and still get the same ratio ? I appreciate that air spaced will have totally different permeability than ferrite based formers and give different results, but conceptually it's still a sound alternative ?
Good video. One question, could you explain how to build for different power requirments and which gage wire and which toriod is needed. Does a #6 material work as well as the 43?
Little disappointing on not seeing the 61 material scan.
I noted strange behavior with MFJ1984MP vs power level - 5watt low swr - 25w and higher, HI SWR at the same frequency. 40 M band. It is supposed to handle 300w PEP
Remember, power rating in any balun is into a matched load. In this case with your 9:1 would handle about 500 watts from a single core into a 450 ohm load. As you stray away from 450 ohms, the power rating goes down !
I'm already seasick after 2 minutes of watching this video, a camera tripod could be an option!
wouldn't a 36:1 or 25:1 UNUN be a better match?
How long is your long wire? Sounds like 16:1 would suit your situation better? 73
Please find a way to STABILIZE THE CAMERA.
Good video man thumbs up
So if your antenna is 900 ohms, then why not make an unun with 1:4 turns. Giving you an z transfer of 16. 16x50 = 800. Swr capable of 900/800 = 1.13 ???
But the impedance of that "long wire" as you call it, isn't going to be 450 ohms on every band and or frequency! Impedances can change greatly as frequency changes!
NOT answering the questions here is a BAD IDEA.
Your math is incorrect