[TowerTalk] F12 Delta 240 performance observation

[john at kk9a.com]

20dB F/B would be incredible for a short 2el 40m beam AT the resonant
frequency.  You should have adjusted your beam for a higher frequency if
you mostly use the phone band.

John KK9A


[TowerTalk] F12 Delta 240 performance observation
from [SPWoo]	[Permanent Link][Original]
To:	 "towertalk at contesting.com" <towertalk at contesting.com>
Subject: [TowerTalk] F12 Delta 240 performance observation


I have a D240 and I haven't
used it much since I put it up this past spring.  Tonight I decided to
run some performance tests.  I found a DX station and I turned the
attenuator
on such that that my S-meter was reading S9 when the beam is pointed at
him.
When I turned the beam 90 degrees away I saw an S7 which is 12 db less
than the
maximum signal strength.  When the beam was turned 180 degrees away I
saw an S9
which is the same signal strength
as when the beam was pointed directly at him.  I'm a little confused
about
this.  This is
supposed to be a yagi and not a rotary dipole!  The listed spec. for F/B
ratio
is 20db at its peak.  I do know that F/B is not constant across the band
for a
yagi.  What kind of front to
back and side rejection ratios should I expect to see on this particular

antenna?  I haven't asked Mark at F12 about this.  I don't want to waste
his
time until I have more info.  Perhaps I'm missing something on the test
or that
I made an error in my antenna assembly.  Your help on this is greatly
appreciated.  73.


Jonathan Woo W6GX