[TenTec] TUNING, MATCHING, TUNERS

[mgoins]

Sure hate to jump into this, but I've used a number of good tuners over the past 28 years (and a number of lousy ones) with 100% homebrew antennas. You "tune" a feedline, in a relatively traditional fashion, by shortening it or lengthening it. That is more-or-less what occurs within a tuner (transmatch, or whatever) as more or less coil (length) is added or subtracted and some "tuning" by length adjustment is taking place. 

So the antenna really is actually "tuned" (at least a little, for what that really matters). It is effectively lengthening or shortening the antenna somewhat by adding coil length in or out, in a manner similar to adding in a length of wire or coax (or a loading coil), thus effectively adjusting the antenna for length slightly (and at the same time, adjusting it for final impedence seen as the impedence changes with length). 

The balun effects an additional impedence change, and that also "tunes" the antenna (for want of a better way to state it) from an impedence matching standpoint. That's why sometimes a 1:1 balun works and sometimes a 4:1 balun is required (so that the final impedence seen can fall within the matching range of the particular tuner).

It's all in what someone wants to call "tuning" and, whatever or however you want to explain it, "tuners" (transmatches, or whatever) allow a load to match the impedence the rig wants to see so that power can be transfered to an antenna. 

They work, but that said, they are also not the answer to sloppy antenna design, and I think that is where a lot of the personl polarization regarding the effectiveness of them comes from. The end effectiveness of any antenna is going to be related to wire diameter, length, wire type, connections, height above ground, etc. - all the things that always affect any antenna's impedence or effectiveness. If what is there is outside the adjustable range of a tuner, no matter what tuner it being used, it simply won't work well. If it is within range (and the antenna is of some solid design and the tuner is reasonably efficient), it will. A tuner might match any length of coax (or whatever feeder) into a good dummy load, but that doesn't make it an antenna.

Some guys have had great results with "tuners" - some don't. I have had (and I've also designed antennas that could not be matched). Depends on so many factors that I feel this type of community polarization has taken place over the years simply as a result of how effective (or ineffective) the results have been for the end user. What you can it, to me, is inconsequential.

One opinion. Mine. Works for me.

Mike
k5wmg
one watt all the time

---------- Original Message ----------------------------------
From: "mgoins" <mgoins at mail.ev1.net>
Reply-To: <mgoins at mail.ev1.net>
Date: Mon,  5 Dec 2005 12:00:15 -0600

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