TO N1RJ
Roger,
Thx for the suggestions to try 50 ohm feedlines vs. the 75 ohm feedlines I am
using now.....I thought it was a good question, and a point I missed in
earlier postings- so I'm posting this reply to TowerTalk.......
I spoke to several 4 sqr owners who used the comtek coupler prior to
construction......I thought 50 ohm looked pretty good too but those who tried
50 ohm feedlines, went back to go back 75 ohm..........looking on page
11-51 on ON4UN's 3rd edition, he states...
"It has been found in practice that with a hybred coupler, having a design
impedance of 50 ohms, it is better to use 75 ohm cable to feed the array
elements. The transformation is such that the impedenace presented at the
hybred coupler result in less power being dissapaited in the dummy load
resistor......"
To be honest, the more I research the subject, of why I can't get the array
to drop any less than 5% into the dummy load, is perhaps due to diameter of
the radiators (Q Factor)......
If I used 25Rohn tower sections and full size 1/4 wave elements....I think
then I'd see a difference- and maybe get below that "mythical" 3% range-
I've just about ruled everything else out without having access to more
technical measuring equipment... 73 Paul N0AH
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