[Antennaware] new to list

Rick Dougherty NQ4I nq4i at contesting.com
Sun Dec 3 09:22:49 EST 2006

Hi all...I am new to this list, but I am hoping that some members might be 
able to assist in an antenna problem I think I have...first off I have 
recently installed a KLM 3 el 80m yagi....its at 175 ft and I spent most of 
the past summer re-building the antenna and installing hardware etc...the 
antenna was built exactly according to KLM spec's in the manual...lengths 
were measured and are within less than 1/8 in from spec.....here in lies the 
problem.....the antenna has a feed point impedance of 100 ohms...almost 
every 3 el design I can find in YO, AO, YW and any other yagi design program 
has antennas with 25 ohm impedances for 3 ele designs....The original KLM 
design used a pair of 75 ohm Teflon coax cables 1/4 wavelength in length in 
parallel to a 1:1 balun at the feed point to provide a nice match....well I 
had to make a single 75 ohm 1/4 to transform the 100 ohm to a 50m ohm 

I plan to make another trip to the top of the tower next week to plot x and 
y values from 3.2 mhz to 4.2 mhz to see if I have overlooked 
something....the antenna as it is now has a W shaped resonance curve...its 
1.2:1 at 3523 and goes slightly up to approx 2:1 and then dips back down to 
1.1:1 at 3799 mhz...so it has a very acceptable match....

The actual performance is far less than I would expect though....there are 
many times at sunset that the 4 square I have will beat this yagi into 
EU....there have only been a few times that the yagi has beaten the 4 square 
in EU or JA....but it sometimes does occur.....the yagi shows approx 20-25 
db f/b.....

Are 80m conditions so flaky that the yagi will at times not equal the 4 
square?? I am puzzled by the 100 ohm feedpoint impedance also??

Any comments either here or offline would be appreciated...thanks de Rick 

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