[TowerTalk] XM-240 owners beware!

[James Sawyer]

I did the same thing with the older model, CD 240.

Jim

-----Original Message-----
From: owner-towertalk+AEA-contesting.com
+AFs-mailto:owner-towertalk+AEA-contesting.com+AF0-On Behalf Of Scott Detloff K8DX
Sent: Friday, October 22, 1999 7:55 AM
To: towertalk+AEA-contesting.com
Subject: +AFs-TowerTalk+AF0- XM-240 owners beware+ACE-



I bought my CushCraft XM-240 just over a year ago, and put it
at the top of 130' of R45 the first of November last year.  In June
the antenna started to have an intermittent and change the resonance
point to near 7.700Mhz+ACE-  Because I've been putting up antennas on
other towers, Tuesday was the first day I had to take it down.
  I had posted a message on TT a few months back about the problem,
and K1ZM had mentioned that the machine screws holding the coil
wire down sometimes +ACI-back out+ACI- , leaving the element electrically shorter.
  When I got the antenna down to the ground, continuity was checked
across the traps and all found to be good.  I also checked continuity across
each element section, and all was O.K.  Now I was really scratching my head+ACE-
  I decided to re-measure across the traps, but this time by shaking the
elements.
Sure enough, the continuity buzzer start to beep+ACE-  When the element was in
it's
normal resting  position, it was shorted.  But I had measured it with the
tip on
the ground, and thus taking the weight and sag off the element.
  I decided to cut back some off the heat shrink tubing of the trap.  Sure
enough,
the machine screw was only 3/4 of the way in, causing the wire attached to
it to
+ACI-float+ACI-.  The screw looks as though it did'nt +ACI-back out+ACI-, since the heat
shrink was
tightly molded to it, and most likely was not tightened at the factory.
  I wasn't about to let this happen again, so I removed all the machine
screws,
drilled through the elements and replaced them with SS bolts.  I'm a big
believer
in using pop-rivets for antenna elements, but CC uses them through the
element
and dielectric material that the coil is wound on.  I wasn't happy with this
mechanical connection either, so I drilled out the pop-rivets and replaced
them
with SS bolts through the elements, and weather-proofed over the top.
  If you still have one of these antennas on the ground, or are thinking
about buying
one, do yourself a favor and remove the machine screws and replace them with
SS
bolts.  Then you won't need to be putting it up twice like I did :-)

73...Scott K8DX


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