TopBand: 160/80 DXped Antenna
Joe Subich, W8IK
w8ik@ibm.net
Sun, 2 Aug 1998 11:03:39 -0400
>
> How about a dual band inverted L? A rope over a tree will hold up the
> wire. Anything from 40 ft vertical and up will work OK on 160.
>
<snip>
>
> You could also make a three bander with a 40 meter trap at 33 feet or
> so! We have made them. Jeff, K1ZM, has a nice design too, but a bit
> stout! He uses RG8 or RG213 to make the traps!
>
AA8U designed a multi-band (trap) antenna for his Cook Island trip some
time back. I believe is it is an inverted L but the "picture" looks like
a T. Here is the information from my "goodie file." The advantages of
the AA8U design over the K1ZM design (which is also in my file) are the
addition of 30 meters, and commercially available traps which provide
smaller size (packing) and lighter weight.
Assuming this is an inverted L design, if support height is a problem
it can actually be bent over at the 40 meter trap instead of the 80
meter trap simply by moving one insulator. The feed impedence will
decrease on 80 and 160 but a good feedline tuner will keep the rig
happy.
73,
... Joe Subich, W8IK/4 ex-AD8I
<W8IK@IBM.NET>
=====================================================================
#####################################################################
# The "Ugly-as-L" 160/80/40/30M DXpedition Inverted-L Antenna #
# Designed and tested by AA8U #
#####################################################################
# Tall Tall #
# Tree HI-Q Insulator HI-Q Insulator Tree #
# O----5/32" Dacron-----====......39'1".....====----5/32"Dacron---O #
# [=] KW-80CW #
# : #
# : #
# : #
# : 23' #
# : #
# : #
# : #
# [=] KW-40 #
# : #
# : 7' 8" #
# : #
# [=] KW-30 #
# : #
# : #
# : 21' 4" #
# : #
# : #
# X feed point (w/28:50 Un-Un on 160M) #
# : 1' 6" #
# _____________________radials________________________ #
# (on ground) #
#####################################################################
Dimensions To Trap Centers Fo SWR Feedpoint R
-----------------------------------------------------------------------
Feed point to KW-30 = 21' 4" 10.12 mHz. 1.10:1 50
KW-30 to KW-40 = 7' 8" 7.05 mHz. 1.15:1 44
KW-40 to KW-80CW = 23' 3.61 mHz. 1.20:1 36
KW-80 to end insulator = 39' 1" 1.83 mHz. 1.60:1 28
(1.0:1 w/28-50 unun)
MFJ-259 resistance calibration:
50 ohms = approx. 42 ohms actual @ 1.0:1 SWR.
Feed point 1' 6" above ground, mounted on short ground rod 2' in earth.
Radials: 5 @ 133'
5 @ 68'
10 @ 33'
Wire used for the radiator and radials is #14 MTW (600 V Insulation).
Using bare copper wire for the radiator will be require these dimensions
to be increased by about 2%.
=========================================================================
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