[TowerTalk] 5el-20m KLM monobander-High SWR

[Dale Green]

Very interesting Peter

The e mail that started this thread is from one of the ops
at my MS contest station.

We have two KLM's stacked at 60/120' on a 20" per side
rotating tower.The top one was installed across the face of the
tower at 120' with no other antennas on the tower and after
installation showed minimum SWR at approximately 14.350.
This was confirmed with a MFJ antenna analyzer.

The 2nd 5 el KLM was then installed across the face of the tower
at 60'. It also shows a minimum SWR at approximately 14.350.

We were using RG213 to feed each antenna thru homemade 4:1
coaxial baluns. These were replaced with KLM baluns but this made
no difference.

We then installed a WX0B phase box and as a phased pair the system
showed a minimum SWR at 14.350 but gain and F/B seemed OK
when compared to other reference antenna's.

We then removed the phase box and hard wired the stack using RG213
to the tee and then 3/4 wave stubs of 75 ohm RG11 to the antenna's.
Still no change in the minimum SWR point..

This system has been in use for several years here and I have just lived
with the high resonant frequency of the array but at the prompting of VA7NT
we have decided to try and lower the system resonant frequency. Hence
the question of a few days ago.

Your response does make me wonder about the effect of the tower.
At some point we may attempt to retune our antenna's so please continue
to post your findings to the reflector.

Very 73,
Dale VE7SV