After I took down the offending yagi and replaced it with what was the
lower one of the stack. I took apart the bad one this morning starting
with the reflector. Cleaned and tightened everything. When I got done
doing the tips of the last director, I went to the center insulator to
check the hardware on it. Problem found: I had a hairline crack in the
jumper that joins the element halfs. When the yagi was tilted past a 45
degree angle, the weight of the element caused the shorting strap to make
contact again. Shorting strap replaced... antenna works again.
What is really depressing is that I checked all of the straps when I was up
on the tower except the last director. I figured there was no way the last
director on a 6 element yagi could cause such a dramatic change in resonant
frequency. Wow was I wrong. BTW, when I remove the shorting strap in the
AO model of this antenna, it does exactly what I observed.
Thanks for all the suggestions.
73
Bill - W4AN - K4AAA
Bill Fisher, W4AN (EX KM9P)
http://www.contesting.com
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