[TowerTalk] Flaky dipole

Drax Felton draxfelton at gmail.com
Mon Aug 1 10:11:33 EDT 2016


What you have is the magic highly reactive spot on a 135' dipole.  It will
create the conditions and difficulty tuning that you describe.
The feedline must be in  odd multiple lengths of 1/8-wavelength on the
lowest operating frequency to optimize the impedance presented to the balun
over the frequency range of the antenna

Look at the instructions from this DXE dipole.  It describes what you need
to do:
http://static.dxengineering.com/pdf/WA-Multi-Band%20DipolesRev2b.pdf

This is also good:
https://www.dxengineering.com/techarticles/balunsandfeedlinechokes/baluns-ch
oosing-the-correct-balun


-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
Timothy Holmes
Sent: Monday, August 1, 2016 8:34 AM
To: ham-antennas at yahoogroups.com; Tower Talk <towertalk at contesting.com>;
CQ-contest at contesting.com
Subject: [TowerTalk] Flaky dipole

Hi folks. Sending this to multiple groups to gain expertise.

My primary dipole is acting strange.  Its 135 feet of wire up 40 feet.  Fed
with ladderline. As I am transmitting I noticevthe swr going from low to
high suddenly for a few seconds and then back.  Initially I thought it was
my auto tuner showing damage, butvI put an MFJ manual tuner in place and I
can clearly see it happening on the meter.  I dont think it is wind moving
the wire, as it was calm when it was happening.  The feed goes from the rig,
through the antenna switch to the tuner, then out the window via a bulkhead
connector and to the 4:1 balun via a 2 foot coax, and then to the
ladderline.

Any ideas on where to look for issues, and or testing methods?

Thanks
TIM
W8TAH
-- 

Tim Holmes - W8TAH
Sent from my LG Stylo
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