[TowerTalk] XM240 SWR plots

[Jim Thomson]

Date: Sun, 25 Mar 2018 15:39:53 -0700
From: "Richard (Rick) Karlquist" <richard at karlquist.com>
To: jim at audiosystemsgroup.com, towertalk at contesting.com
Subject: Re: [TowerTalk] XM240 SWR plots

<  When I first got my MonstIR up, I took 
advantage of the fact that I could adjust the length of the three 
elements individually.  Just to prove a point, I tuned up the antenna 
the usual way for CW (all 3 elements optimized); then I QSYed the
radio to the phone band.  The SWR was not ridiculously high and a
radio with a tuner could drive it.  I retuned just the driven element to
get the best SWR I could, without changing the parasitic elements.
That improved the SWR somewhat.  However, as expected, the antenna 
suffered a substantial drop in gain and F/B ratio to where it wasn't
much better than a rotatable dipole.

Rick N6RK

##  IF  you had left all 3 els alone... and just say used a tuner, did the FB / FR /gain drop off  at upper end of band ?  
When I see typ plots of  3 el yagis, tuned for the lower part of the band, the gain actually increases a tiny bit towards
the top of the band.... meanwhile ..at top of band, the swr and FB / FS  go straight to hell..quick like. 

Jim  VE7RF