In this video I show you the steps in which I made my weatherproof 9:1 unun. Toroid cores. www.amazon.com... Epoxy www.amazon.com... Silicone Molds www.amazon.com...
Iron powder toroid cores are not suitable for baluns and ununs! This is due to a low permeability. These toroidal cores are only suitable for resonance circuits and induction coils. For baluns and ununs use ferrite cores which have a higher permeability! The reactance XL (alternating current resistance) of the transformer must be at least 5 times greater than the impedance to be adjusted. This is necessary to minimize the influence of the transformer, so that a reasonable return is achieved. The reactance depends on the core material, the number of turns and the frequency at which it is operated. What you should definitely not do is pour the transformer in epoxy resin, a transformer gets hot, and this heat must be able to dissipate.
My major concern is the heat retention being so perfectly sealed in epoxy. This build also prevents you from accurately checking temps since you can’t touch it or put a thermocouple on it. I would seriously consider doing a build where the pl259 and wing nut connections are encased in epoxy and maybe the lower 10% of the core is also but 90% of the core is fully exposed to the air for optimum heat transfer.
Nice project and vid. I built one of the T130-2 9:1 unun’s too and got the same result on the lower bands. I’m going to try a type 43 toroidal and that should work better on all bands.
As I know resine is not compatible with HF. That would be nice to test before and after to check if the issue is the Balun + Antenna or the Resine + Balun + Antenna . 73
The resin 9:1 works just the same as the ones I've made of the same materials that are not in resin. The resin has no measurable affect as far as I can tell.
Nice… I was just going to ask how it did with dissipating heat but you answered at the very end… seems like a cool project even if you had to back down the power. I have partially filled 1 of my 9:1’s with a fluffy spray foam. Keep hamming and 83 de W3OY
Is that resin rated as an electrical insulator? Some epoxy resins are somewhat conductive and could be putting a resistance on the connections that shouldn't be connected.... Also your wiring doesn't look like John's M0UKD schematic. C2 and A2 looks correct, but correct me if I'm wrong, but it looks like on camera you've wired A2 with B2, and B1 with C1, when it should be A2 with B1 and B2 with C1. Even though the colors look correct, the high and low impedance sides of that transformer are mixed up.
Thanks! I've made enough of these out of the same parts that I don't really even test them anymore....they all test just about the same. I only showed this one so I didn't get complaints for not lol
Why do folks think a 9:1 unun is so great ? It is designed for use with antennas that produce 450 ohms impedance and a long wire, random ware, end fed half wave is most of the times going to anything except 450 ohms ! And they are most efficient when feeding 450 ohms, so when you stray away from that 450 ohms, the efficiency decreases. If you connect a wire to it and it shows a high swr and requires a tuner, then the wire you have connected is not 450 ohms. Also, a mix 2 powdered iron core is designed for use as inductors for things like tuned circuit, not for a 9:1 unun. The proper core for a 9:1 unun is the mix 61 ferrite ! Also, potting a unun or balun traps heat that can damage the core - it needs air circulation to help keep it cool !
I'm digging into this topic now. Plenty of smarter people than me saying mix 2, 43 and 61. Nobody gives a great explanation. Maybe throw some math in the comments so the new hams like me know why I should use what mix
Yes I was thinking the same. This is the worst design of UNUN I have ever seen - which is why no reputable commercial unit is made this way. SWR will rise rapidly above 65c.
I don't think heating with this size core and wire size would be a problem at 100/200 watts. I prefer 240 or larger cores and Teflon insulated #12 wire for higher power, even #10 for legal limit. If you can't get bigger cores you can stack 3/4 of them for more suds. 50 size cores work fine for 10w. If you do some antenna modeling b4 hand it might surprise you to see how low the screen can be.
The unun can be affected by core size, wire size, and a number of other variables. I've always gotten the best results with this type of wire and these cores with 9 turns. 8 or 10 turns would be feasible to use if using slightly different components.
@@mikehannah6054 I have had them mounted outdoors, not even in a box and the only thing sealed was the coax connection and the balun mounted on a piece of plexiglass for a strain relief. Rain and snow had no effect on it at all !
OOOOOH YES GOOD CONDITIONS THE SHITTY / MAGIC ANTENNAS GET NEW REDICULES LIFE I. Got 5 difrent designs of this garbage!! WHAT MAKES THIS THE ONE TO RULE THEM ALL!! BY MY COUNT THEY ALLLL ARE WASTE OF TIME
Iron powder toroid cores are not suitable for baluns and ununs! This is due to a low permeability. These toroidal cores are only suitable for resonance circuits and induction coils. For baluns and ununs use ferrite cores which have a higher permeability!
The reactance XL (alternating current resistance) of the transformer must be at least 5 times greater than the impedance to be adjusted. This is necessary to minimize the influence of the transformer, so that a reasonable return is achieved. The reactance depends on the core material, the number of turns and the frequency at which it is operated.
What you should definitely not do is pour the transformer in epoxy resin, a transformer gets hot, and this heat must be able to dissipate.
Sounds like you might want to make your own video.
My major concern is the heat retention being so perfectly sealed in epoxy. This build also prevents you from accurately checking temps since you can’t touch it or put a thermocouple on it. I would seriously consider doing a build where the pl259 and wing nut connections are encased in epoxy and maybe the lower 10% of the core is also but 90% of the core is fully exposed to the air for optimum heat transfer.
Thx for vid. Would make an epic teaching tool at a club. Thermal camera on this would be neat during transmission to see where electrons bunch up.
Enjoyable video on ununs. I like the potting material you used. 73 de W4FJF.
Nice unun build
Nice project and vid. I built one of the T130-2 9:1 unun’s too and got the same result on the lower bands. I’m going to try a type 43 toroidal and that should work better on all bands.
As I know resine is not compatible with HF. That would be nice to test before and after to check if the issue is the Balun + Antenna or the Resine + Balun + Antenna . 73
The resin 9:1 works just the same as the ones I've made of the same materials that are not in resin. The resin has no measurable affect as far as I can tell.
@@mikehannah6054 Thanks for the feedback.
Maybe imbed a loop of stiff wire in the resin or drill a hole for a loop of paracord to be used as a hanger.
Was thinking about trying an eye screw hanger on it. Not too sure how it would work with the resin though.
@@mikehannah6054 Drill & Tap.
I would jam wax into the connector and get the threads coated. It would make it easier to pick out any pouring mistakes.
also glad to see you post again. Its been 2 years lol. wow dude. been subscribed for a while and just noticed that. Glad youre still there.
Thanks for stopping by after so long, it's been a few lol
Great idea, get to actually see the guts. I want to do a 49-1 like that ⚡
Appreciate it!
Give some consideration to putting your camera in manual mode. Use a higher f-stop to improve your depth of field. Good video.
make multiples and run them in parallel to share power between them. Would look even cooler!
You can just stack ferrite cores and make the whole thing thicker with the same number of wires and turns. Or just use a bigger diameter core.
Dang nice job!
Nice… I was just going to ask how it did with dissipating heat but you answered at the very end… seems like a cool project even if you had to back down the power. I have partially filled 1 of my 9:1’s with a fluffy spray foam. Keep hamming and 83 de W3OY
I've never actually used more than 100W lol. Thanks for stopping by!!!
@@mikehannah6054 me neither but I run CW most of the time so I bet a 240 core would probably be enough.
Is that resin rated as an electrical insulator? Some epoxy resins are somewhat conductive and could be putting a resistance on the connections that shouldn't be connected.... Also your wiring doesn't look like John's M0UKD schematic. C2 and A2 looks correct, but correct me if I'm wrong, but it looks like on camera you've wired A2 with B2, and B1 with C1, when it should be A2 with B1 and B2 with C1. Even though the colors look correct, the high and low impedance sides of that transformer are mixed up.
That's an awesone idea. Thanks for sharing this. 73's...
Thanks! It's held up well with my 100w I use it with.
@@mikehannah6054 may I ask sir, since I'm new to this hobby, can I use this with any dipole to what ever frequency I will be using it?
Thank you for such a clear explanation. ;)
If it doesn't effect the ops it's a great idea.
that is a sweet build.
Thanks!
Nice. Very fancy. 😂
Wow this is slick (Thanks) for this cool Idea
Looks great.
Thanks cowboy
What’s the blue flame for???Moral support???
Awesome project, but wouldn't it be good to test it before you poured the epoxy?
Thanks! I've made enough of these out of the same parts that I don't really even test them anymore....they all test just about the same. I only showed this one so I didn't get complaints for not lol
Nice project
Thanks!
Why do folks think a 9:1 unun is so great ? It is designed for use with antennas that produce 450 ohms impedance and a long wire, random ware, end fed half wave is most of the times going to anything except 450 ohms ! And they are most efficient when feeding 450 ohms, so when you stray away from that 450 ohms, the efficiency decreases. If you connect a wire to it and it shows a high swr and requires a tuner, then the wire you have connected is not 450 ohms. Also, a mix 2 powdered iron core is designed for use as inductors for things like tuned circuit, not for a 9:1 unun. The proper core for a 9:1 unun is the mix 61 ferrite ! Also, potting a unun or balun traps heat that can damage the core - it needs air circulation to help keep it cool !
Thats funny. I`ve build plenty of 9:1 ununs both with 43 mix and 61 mix. 43 mix for me works better
I'm digging into this topic now. Plenty of smarter people than me saying mix 2, 43 and 61. Nobody gives a great explanation. Maybe throw some math in the comments so the new hams like me know why I should use what mix
Yes I was thinking the same. This is the worst design of UNUN I have ever seen - which is why no reputable commercial unit is made this way. SWR will rise rapidly above 65c.
I don't think heating with this size core and wire size would be a problem at 100/200 watts. I prefer 240 or larger cores and Teflon insulated #12 wire for higher power, even #10 for legal limit. If you can't get bigger cores you can stack 3/4 of them for more suds. 50 size cores work fine for 10w. If you do some antenna modeling b4 hand it might surprise you to see how low the screen can be.
Has it melted yet?
At the 100w or less I use, it doesn't even really get warm. Been using it since I made it with no issues.
Kool....😀😀😀
The diagram has eight wraps around the toroid. But there are 9 wraps around the actual toroid.
The unun can be affected by core size, wire size, and a number of other variables. I've always gotten the best results with this type of wire and these cores with 9 turns. 8 or 10 turns would be feasible to use if using slightly different components.
@@mikehannah6054 Be careful with that because the the impedance vs number of turns is a second order function.
Love it, but mine would incinerate doing that.
My little 100w does ok with it. You may need some larger parts...lol
9:1 balun
Not a good ferrite for baluns
FROM BANGLADESH..
SELL IT as a product!
Not cool ! Sealing it in plastic will trap heat and could cause failure !
I only use 100w and I haven't even seen it get warm. Might fail eventually, but the chances of moisture making the others fail are there as well.
@@mikehannah6054 I have had them mounted outdoors, not even in a box and the only thing sealed was the coax connection and the balun mounted on a piece of plexiglass for a strain relief. Rain and snow had no effect on it at all !
OOOOOH YES GOOD CONDITIONS
THE SHITTY / MAGIC ANTENNAS
GET NEW REDICULES LIFE
I. Got 5 difrent designs of this garbage!!
WHAT MAKES THIS THE ONE
TO RULE THEM ALL!!
BY MY COUNT THEY ALLLL
ARE WASTE OF TIME
This was a real cool project. I definitely want to give it a try . Enjoy your videos. 73 AE4OY William Peacock 🦚 EM-81UF Blackshear,GA 😎
Thanks William!