Topband: 160M - sunt fed - broaden swr
tony.kaz at verizon.net
Sun Feb 5 17:27:27 EST 2006
I have been shunt feeding my 80' Rohn 45 tower. Shunt feed is attached at
38' because I have a tribander mounted at 42'. The shunt feed was a single
#12 wire spaced 2' from the tower.
SWR was 1.80 = 2.8, 1.85 (resonance) = 1.2, 1.90 = 2.4.
I made a new shunt feed using 3 #16 wires with the same 2' spacing from the
tower and the same length. The total spacing of the 3 wires is 18" and
parallel to the tower face.
SWR now is 1.80 = 1.8, 1.84 (resonance) = 1.1, 1.90 = 1.9.
Seems like the project was worthwhile to increase bandwidth.
Next project is to add a cap and relay at the feedpoint so I can cover more
of the band from the shack with just a flick of the switch. I plan on using
an RF1E vacuum relay and an "857" cap rated at 15KVDC. Any concerns with
this type of cap and relay?
I have several of the smaller "8548" type caps rated at 5KVDC. But not sure
if they are rated high enough?
Tnx for any feedback.
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