[TowerTalk] 80m Newbie...Help w/ Inverted V Please

[James C. Hall, MD]

Hi Robin:

For the inverted-V, I would simply lengthen or shorten the V elements
depending on your chosen frequency. What I have done more successfully is to
take it up higher and convert it to a delta loop. Feed it with ladder line
at one of the lower corners to a 4:1 balun and then coax to the rig. Works
great for me !!

73, Jamie
WB4YDL

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Robin Midgett
Sent: Wednesday, September 29, 2004 3:14 PM
To: towertalk at contesting.com
Subject: [TowerTalk] 80m Newbie...Help w/ Inverted V Please

Hi,
My attempts to make an inverted V resonate on 80m are not meeting with 
great success. I've put up inverted V antennas before (10m & 40m) and they 
worked very well...not so in this case; 2.8:1 (feed point fully up) is the 
best match I've seen yet. I'm hoping some of you more experienced will have 
some constructive input.
Here's the configuration:
130' of Rohn 45G, on fairly flat, level ground with a 24" (out from the 
tower) aluminum stand off bracket at the 60' level. A rope and pulley rig 
is used at the end of the stand off to haul the feed point of the V up to 
the 60' level.  Each leg of the V is ~62' long, and there is ~ 80-90 
degrees between them. The ends of the wire (14 ga. stranded) are formed 
into a loop, which is where a small piece of rope attaches and anchors to a 
stake in the ground. Pretty typical stuff, from all I've seen before.
The tower is guyed at 30' intervals to posts 85' from the tower base, so 
guy wire lengths (all 1/4" EHS) are 90', 104', 124' & 127', no insulators 
on any of them.
With the feed point pulled up all the way, ~3:1 is the best match I get. If 
I lower the feed point to ~50', and the ends of the wires are drooped onto 
the lawn, the match improves to ~1.8-2:1.
I'm using a MFJ-269 to make the measurements. I find really good matches 
(~1.5:1 or better) at 12 MHz, and odd multiples up the bands.
I've changed the coax, no help. Removed the coiled coax choke; no help. 
Checked continuity from shield to end of one wire, OK; from center pin to 
end of the other wire, OK; no shorts, either.
Is this possibly a case of guy wire coupling/interaction? Might raising the 
feed point to a higher level help the match? Should I extend the distance 
from the side of the tower to the feed point?
Thanks,
Lost in H.F....going back to VHF+....Robin KB4IDC

"Success is the ability to go from failure to failure with no loss of 
enthusiasm." -Winston Churchill

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