If you do a search on that internet thing for "9:1 unun" you'll find all kinds of diagrams, far better than what I could draw for you. I mostly wanted to share this because I was pleased with how I was able to make myself a "mini" 9:1 unun. I managed to squeeze the whole thing into a 3x2x1 project box. It won't handle high power, but for 100 watts or less here at home, or as another piece of ammo in the portable kit, I think it will be just the ticket!
I've been fiddling with a couple antenna things because I want to get some more permanent options in the air while I work on the home shack (you can get up to speed on that project by starting here and following the links at the end of each post.) and eventual tower project. As I was messing around, it dawned on me that the desk I am sitting right now, faces a window that looks over the top of our addition and into the back yard. The addition has a metal roof. Why not throw a random-wire end-fed into the trees across the back yard, and use the metal roof as a counterpoise? End-fed antenna's usually need an unun to transform the high impedance of the end of the wire into something that the radio or tuner will be happy with. This usually means that a 9:1 unun is just the ticket. With that thought, when I should have been going to bed, I was making this little number out of scraps of wire and hardware from my garage, along with a couple bits from the electronics stash: If you do a search on that internet thing for "9:1 unun" you'll find all kinds of diagrams, far better than what I could draw for you. I mostly wanted to share this because I was pleased with how I was able to make myself a "mini" 9:1 unun. I managed to squeeze the whole thing into a 3x2x1 project box. It won't handle high power, but for 100 watts or less here at home, or as another piece of ammo in the portable kit, I think it will be just the ticket! Once I had the thing built, I threw a 650k resistor across the terminals (because that's what I had handy), and then put the antenna analyzer on it just to make sure I had the winding correct and had it wired correctly. It read at something in the neighborhood of 1.5:1 across the entire HF spectrum, so I'm gonna take that as a good sign! All that will be left to do is to attach an appropriately random length of wire to it, connect the counterpoise terminal to the roof, and hook it up to the rig to see what happens when it actually has some power applied. Just for fun, here's a couple more pics of my handy-work as I threw it together: . .
5 Comments
Dean Norris
9/15/2017 00:41:32
Dammit! Now I wanna build one!yes
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Doug KC3HRB
9/25/2017 21:57:17
Ordered a couple T130-2 torrid and made one tonight...actually I made two. It's funny how one little twisted wire can make for such frustration. I used 22g enamel coated wire, which of course is all the same color so it was an honest mistake. Winding #2 was much better. Made a 59/59 with K4V in Ocala FL on 40m. Then to bed...why must sleep get in the way when I want to play radio?
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Vance - N3VEM
9/26/2017 07:06:07
How true! All too often I have little goofy things like that which set me back on a project far longer than they should! Glad it worked out!
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Vance - N3VEM
6/2/2018 23:05:49
Good luck! I got a bunch of cases when Radio Shack shut down, and we do have one private Radio Shack dealer left in our area - if it weren’t for that I’d probably have to order them online.
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- N3VEM - Welcome to my Ham Radio Blog! This blog was started primarily to share my two concurrent shack builds - my mobile station and my home station. Over time, this has grown to include sharing about my operations, and general radio-related thoughts that I have as a newer operator. Proving that hams do indeed still build stuff!
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