[TowerTalk] XM240 Experiences

[AA4NC@aol.com]

In a message dated 9/21/98 10:10:00 PM GMT Daylight Time, Fredrick_Sanborn-
WFS004@css.mot.com writes:

<< Tower talkonians please heed the warning - Check your element to boom
 mount and boom to mast mount alignment before installation!  I cannot
 fix the element to element alignment without removing the antenna back
 to ground level so I will live with that but I plan to fix most of the
 horizontal alignment by removing the 2 boom pinning bolts at the mast
 plate, loosening the 8 bolts at the plate and redrilling the pinning
 bolt holes into the boom. >>

I wonder if there is a way to "pin" the elements to the boom? I've done this
on my 402CD by using a small SS machine screw through the clamp into the boom.
It gives enough mechanical strength to keep the element aligned through the
tramming and mounting process, and (so far) has kept the elements from being
misaligned by the wind


<<In the shack the results were quite good.  Using the CC dimensions for
CW tuning (7025 according to CC) my SWR is 1.5 at 7.0, 1.2 (min.) at
7055, and 2.0 at 7.175 using 5/2wl of 70 Ohm hardline,  27' 50 Ohm
jumper at antenna, and 12'  50 Ohm jumper at shack end.>>

Compared to mine (and other) 402CDs, that sounds a bit narrow. Using an
interpolation of the 402CD dimensions (I think this is what K7LXC calls his
"secret" dimensions) I get 7.000 - 7.260 for  2:1 VSWR bandwidth. I assume
that a tad shorter dimensions will stretch the bandwidth on this antenna as
well, by raising the resonant frequency to about 7100 . (Chad, WZ - did you
try that?)

I have an XM240 still in the box that I plan to put together next weekend. I
plan to stack it with my 402CD. I appreciate all of the construction tips.
Keep 'em coming...

73,

Will

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