On Jan 9, 2005, at 8:48 AM, Vic Rosenthal wrote:
R.Measures wrote:
Ironically, even though the balanced-L network Z matcher was invented
by Bell Labs in the 1930s, and E. F. Johnson Co. mfg all of the
components needed for a balanced L network antenna tuner in the
1950s, they definitely dropped the ball with their Matchbox®.
At the time the Matchbox was introduced, one of the biggest problems
facing amateurs was harmonic TVI.
A low-pass configuration, balanced-L Z-matching network attenuates
harmonics.
The link coupled design was very effective in preventing VHF harmonics
(at least those flowing inside the coax) from reaching the antenna,
especially when combined with a low-pass filter in the coax line.
So although the link-coupled circuit does have a limited range
compared to other designs, there were good reasons for using it.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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