[TowerTalk] XM240 Experiences

[Sanborn Fredrick-WFS004]

  Over this past weekend I had the experience of installing CC's XM240
at my QTH up at 100' and I thought I would share some notes with others
here on the reflector.  I will not discuss my antenna assembly issues
here as that was covered previously by Chad WE9V and also Steve VE6WZ in
their postings.
  I want to second the opinion of Steve concerning CC's U bolt and V
block.  I thought I had taken care of the galling and mis-alignment
problem by drilling the V block holes slightly larger before
installation, however I didn't take into account that the mast would not
allow me to slightly flex the U bolt to fit into the V block.  I spent
20 minutes up the tower trying to get the V blocks on the U bolt.  Not
nice and the ground crew gets very impatient.   Once I had the mast to
boom plate bolts tightened, I looked to see just how beautiful my
antenna looks against the horizon, but much to my dismay the elements
were not perfectly horizontal and also out of alignment with each other.
 I previously had been commenting to other Ham friends including one of
the ground crew on such a great bit of hardware CC had with this antenna
- no alignment necessary, just bolt the thing together, no fuss- NOT.
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 also take issue with CC's balun box attachment to boom.  The nut and
bolt threads on the UHF connector side of the box comes so close to the
connector I was unable to do a good weather proofing job on the
connector feedline.  I removed the balun mounting bolt on the connector
side, loosened the other, and cocked the box at an angle to the boom in
order to apply the necessary materials.  The box needs longer L mounting
brackets to avoid this issue in my opinion.
  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.  I compared the
XM240 with a 40M Half-square at 37' pointed in the same NE direction on
RX with several US and a few Eu stations with the XM240 equal or winning
in all situations.  Much QRN last night and I was unable copy the weaker
<S5 stations.  I will need more time in the shack to evaluate this
antenna and also I could not verify the max 28dB F/B ratio (wink wink
-Hi Hi) as the beam is not able to be rotated since the install could
not be completed until the alignment issue is fixed - Thanks CC!
  Since this is my first submission to the reflector, I also want to
take this time to thank everyone on the reflector for their knowledge
base sharing.  I have learned much in the last 5 months as a subscriber
for my 100' tower install, etc.!!

73   Fred KG9X  wfs004@email.mot.com

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