I have frequently used the T1 with a balanced antenna (open wire feed line, etc.) simply by connecting one side to the feed line to the "hot" center pin and the other to the shield or ground terminal on the T1.
Yes, a slight amount of "unbalance" may be introduced, but usually much less than the natural unbalance in a doublet or loop due to surrounding objects near the antenna, even when the antenna is in a fixed location up in the clear. Such unbalance may shift the pattern slightly but IMX, has no detectable effect on the effectiveness of the antenna. Curious, I have measured the current in each side of the feed line in several setups and found no significant difference with or without a balun. What I have found that happens in rare occasions is that there is a voltage "loop" (high rf voltage) point at the feed point at the T1. That can raise the entire rig - T1 and the transmitter - well above ground causing tuning and RF "feedback" issues. I have only encountered that rarely. A balun may help in that case, but I've always cured it by changing either the length of the feed line or the antenna. My favorite "ad-hoc" field antenna for QRP work is two 45 foot lengths of insulated wire that terminate in a male BNC connector, one side to the center pin and one to the "shield". If I can, I toss both in trees so the angle between them is at least 90 degrees. Sometimes I use the tiny plastic "clothes pins" sold for office use to hold papers to hold the two wires near each other for ten feet or so, forming an open wire feed before the wires head off in roughly opposite directions. If it's inconvenient to get both wires up and in the clear, I just toss the one connected to the center pin into a tree or other somewhat lofty location and leave the other wire on the ground as a 'counterpoise'. 73, Ron AC7AC -----Original Message----- Hi Randall, You can connect a random wire antenna directly to the T1 (then toss it into a tree, etc.) without a feedline. But you'll need to add a ground counterpoise wire, too; use at least one wire cut to 1/4 wavelength on the lowest band in use. If you want to run a balanced feedline to the antenna, then a BL1 or BL2 would be required. The counterpoise or ground wire may then be optional, but is still recommended. 73, Wayne N6KR On Nov 6, 2011, at 5:59 PM, Randall wrote: > > I'm assuming when using the Elecraft T1 Miniature ATU with a wire > antenna, > dipole or long wire, the BL2, 1:1 & 4:1 (switched) Balun, is > required. > Is this correct ? > > thanks ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
