On Wednesday, March 26, 1997 3:44 AM, Chris R.
>>>How about a thread about antenna switching at the big contest
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Here at KG5U, the antenna arrangement is pretty simple:
Two A3's (70' and 40'--hi/lo/both selectable), 40m inv vee,
My contest operations with two radios is pretty limited
yet and I usually operate QRP (read: s&p 70 or 80 percent of
the time). I figure the times 20m (15m?) will be open, the other
lower bands won't and I will be at 1 radio operation. The
following switch configuration has no capability for 2-radio
operations with my tribanders....yet...
My two-radio/antenna switch is a two pole, 12 position rotary
swich. One pole controls one radio/antenna relay set(3) and
the other pole controls the other radio/antenna relay set (3).
Every 6th position of the switch is daisychained to it's
corresponding position (e.g., pos1-->pos7, pos2-->pos8, etc)
to permit complete rotation of the switch. This way, I am
never more than a couple of switch positions away from any
The switching pattern is (radio1/radio2):
a3/40, a3/80, 40/a3, 40/80, 80/a3, 80/40
Each radio is represented by a three pair of relays; a pair for each
antenna. Only one of the two relays in a pair may be turned on at
any one time.
Two rows of LED's, three in each row, give the antenna connection
status for each radio.
Radio A3 40m 80m A3
1 O O O O H
2 O O O O L
A 12-position, 4 pole rotary switch controls the hi/lo/both
relays for the two A3's. A pair of LEDs separated by a half
inch from the other antenna/radio LEDs but in line with them
shows the hi/lo/both status. Again, the rotary switch positions
are daisy chained to permit continuous rotary switch selection
(no A3 antenna configuration is more than two positions away).
The switchbox also contains the switches for radio/headphone
switching, radio mic, ptt and keying.
The relay box is located at the antenna patch panel out in
One of these days, I am going to build a decent relay box to
house all the relays (they're in two bud boxes right now and
have 1-foot RG-58 cables (my only use of RG-58--only 100w and QRP
done at KG5U) with PL259s hanging out of them--I barrel
them to the antenna feedlines out to the tower and to the
radio's cable runs into the house.
Power for the relays is provided by the control cable (old rotor
control cable) from the switch box.
Dale Martin, KG5U
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Administrative requests: towertalk-REQUEST@contesting.com
Sponsored by: Akorn Access, Inc. & N4VJ / K4AAA