When you select 1 or 4 antennas the Stackmaster uses the 50 ohms stubs to
match the impedance. When you select 2 antennas the Stackmaster uses two 75
ohm stubs for the match and when you select three antennas it uses a 50 ohm
and a 75 ohm stub. So, it appears that you only have problems when one or
both 75 ohms stubs are used. I would make sure that they are the correct
length and that they are made from 75 ohm cable such as RG-11. You should
also make sure that the correct stub relays are engaged when you select the
two and three antenna positions.
73,
John KK9A / P40A
----- Original Message -----
From: "Courtney Judd - K4WI" <k4wi@earthlink.net>
To: "TowerTalk" <towertalk@contesting.com>
Sent: Sunday, July 25, 2004 12:22
Subject: [TowerTalk] Antenna problems
Hello all; I thought I would throw this annoying little problem out to the
group and see if anyone has any suggestions. First a description of the
system: this is a 4 hi stack of M2 7 el 10 mtr yagis 7/7/7/7 @
140/105/70/35 fed with equal lengths (80 ft) of RG 213 to a WX0B
Stackmaster then LMR600 to the shack. Top rotates 360 deg and bottom 3
rotate 300 deg on swing arms. The problem is the same regardless of
direction any or all are pointed. The problem: swr on all individual
antennas is a perfect 1:1; swr is 1:1 on any combination of 3 antennas; but,
any combination of 2 antennas or all 4 results in a swr of 2.3:1. I have
swapped out all the StackMaster controls and added an extra 6 feet to each
feedline as possible fixes but had no effect. The tower is Rohn 25 guyed 3
ways 4 times. The antennas are mounted just above each guy point which gave
plenty of rotating room. Any ideas or solutions? Thanks and 73's Cort
Courtney Judd K4WI / NA4W
2300 County Road 61
Uniontown, Al. 36786
Check out my web site:
http://home.earthlink.net/~k4wi/k4wi/
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
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