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On Sat, 17 Jan 2009 12:44:05 -0800 (PST), JIMMIE
wrote: I was considering using a TV type 4:1 balun on 2 meters. Does anyone know how much power these can handle? I remember a guy doing this when I was a teenager(long ago) but I think the baluns were built a little stouter back then than they are now. May I suggest using a coaxial cable 4:1 balun instead of ferrite core type. A 1/2 wave electrical length of coax cable, some soldering, and you're done. For just 2 meters, the bandwidth is just fine and the loss is no more than that of the coax cable. For low power, small diameter RG-174 type coax is fine. I use 4:1 coax baluns for matching 300 ohm folded dipole antennas: http://users.belgacom.net/hamradio/schemas/14balun.gif The common TV balun has two xfomers inside, which are sometimes combined on a single core. See schematics at: http://members.tripod.com/rclindia/trans.html http://www.electronics-tutorials.com/basics/baluns.htm However, if size is an issue, I guess the coax balun is a bit large. For just 2 meters, the ferrite core is not necessary. Just find a block of PTFE (Teflon) or plastic, and drill it to resemble the TV balun core, use 2 PTFE toroid cores (if you can find them), or simulate a torroid with a stack of nylon washers. Then wind the 2 pairs of 2 wires through the holes and bring out the connections. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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