[TowerTalk] 2 Meter Balun Question
patrick_g at windstream.net
Thu Nov 21 08:19:34 EST 2013
I have used a mast head mounted shunt fed 1/2 wave marine band antenna
(Metz) on our sailboat interchangeably (1X2 coax switch) between my 2M and
marine band VHF rigs. At a height of 50 ft or so it worked quite well on
both bands. The coax ran inside the aluminum mast. No ferrites were used.
I had no observed problems so I can't say how anything would have been
improved with ferrites. Ferrites certainly would not hurt anything even if
they didn't help. My 25 watt marine rig worked the various coastal marine
telephone installations quite well at distances of 100 miles or more.
Likewise I worked mountain top repeaters at ranges up to nearly 200 miles.
No, I have no polar plots of radiation patterns, charts of field strength,
or VSWR charts but the setup worked reliably over a period of a couple
decades so that should validate its efficacy.
The only problem I had was on one occasion when I had to disconnect the coax
from the back of the marine VHF due to static discharge/sparking. The
antenna was a DC short to the aluminum mast and stainless steel standing
rigging. The boat was fiberglass so the chain plates were insulated. In
retrospect it is obvious to me that I should have bonded the mast to the
keel and the static electricity collected would have been drained to the
ocean. Hopefully I have gained some knowledge in the intervening 35 or so
Short version: Try it. Perhaps with and without ferrites if you are feeling
Sent: Wednesday, November 20, 2013 5:02 PM
To: TowerTalk at contesting.com
Subject: [TowerTalk] 2 Meter Balun Question
I'm "hoping" to use a Marine Band Base Antenna on the 2 Meter band and
was wondering IF there would be any advantage to putting a 1:1 balun at
the feed point of the antenna? Just thinking out loud about the SWR &
radiating from the feedline coax?
Hope I don't sound foolish!!!!!
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