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Long inverted V not working well, why?
Rick (W-A-one-R-K-T) wrote:
Seems very strange. Any ideas that might account for why the V doesn't work better? The key is the combination of feedpoint impedance and length of the ladder-line. Some lengths of ladder-line at some frequencies are close to worst case. For instance, if the feedpoint of the 160m dipole is 6000 ohms on 75m, you certainly don't want to feed it with 1/2WL of ladder-line on 75m. The free demo version of EZNEC available from eznec.com will probably tell you what is wrong with your installation. There's a DOS program on my web page that will tell you the optimum lengths for feedline. It can be downloaded from http://www.w5dxp.com/imax.exe For instance, with a 260 foot dipole used with 450 ohm ladder-line on 3.8 MHz, the optimum feedline lengths are ~55 feet and ~172 feet. If your feedline length is halfway between those two lengths, i.e. ~113 feet, it is a worst case impedance situation for 3.8 MHz. -- 73, Cecil http://www.w5dxp.com |
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