I am interested in Frank, W3LPL's, arguements in favor of the T-match
versus the Gamma Match. As I recall, the primary "advantages" Frank
listed were 1) needed no series capacitor and 2) was used with a
"bullet-proof" half-wave balun (to match the 200 ohms to 50 ohms).
It seems to me that those two points can also be used, with slight
modification with the Gamma Match. First, the Gamma match is one half
a T-match, and can also be used without a series capacitor by adjusting
the element lengths to introduce the proper amount of reactance. That is
what Frank is already doing with his T-match. Note that in the ARRL
antenna book the development of the T-match shows a pair of series capacitors.
It would seem to me that adjusting TWO sliding shorts on a T-match as well
as the element length is more touchy than ONE sliding short and the element
length with a Gamma match (sans capacitor). Having said this, I know from
experience that using the series capacitor makes tuning the Gamma MUCH
easier than finding the magic combination of Gamma rod length and element
length! But I believe the same thing could be said about the T-match.
Second, the Gamma match could use a "bullet-proof" choke balun which is
even easier to make and install that the half-wave balun. Also, whatever
bullet-proof construction secrets Frank has developed for his T-match should
also be equally applicable to the Gamma match, which is one half of a T-match.
Question: Is the T-match juggling of length parameters REALLY simpler than
the Gamma match juggling? And is there any good reason to change to the T-match
in HF antenna construction?
Terry Zivney, N4TZ/9
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Administrative requests: towertalk-REQUEST@contesting.com