Great ideas, thanks for all the responses.
I have been testing my D40 on a tv roof support and a tv mast on the ground
about 16 feet up. (which probably explains the problems tuning). I
misjudged how swampy my backyard had gotten in all the rain and came home to
find my D40 stuck to my kids playset. From what I can tell, it blew over,
landed directly on the end of element, stuck into the ground and pivoted on
the outermost tubing segment. Surprisingly, I could rebend the tubing,
straighten it out and the rest of the antenna completely unharmed.
I was impressed. So, just for FYI, cushcrafts support was outstanding, even
if their phone service isnt great, I got an e-mail response within hours.
The replacement was around $10 and also went ahead and bought the D4's truss
for $20 to add support for the sagging elements, only to reduce the D40 to
Steppir interractions...!!
Michael K3MH
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com]On Behalf Of N4KG@aol.com
Sent: Monday, April 14, 2003 5:54 AM
To: TowerTalk@contesting.com
Subject: [TowerTalk] CC D40
Cushcraft has done the tuning for you. Just use the supplied dimensions for
CW or SSB or mid-band. My CC 2L40 is tuned for CW and works like a champ!
My *guess* is that you need to get a dipole at least 1/4 WL above ground for
resonance to be reasonably independent. Note that IMPEDANCE will vary with
height.
To reduce SAG, insert the next smaller size tubing in the first section of
each element half. This will raise the wind rating from >70 mph to >90 mph.
My CC
2L40 survived a small tornado that took out two 75 year old hardwoods and
dozens of younger 80 ft trees (estimated winds 80 to 90 mph).
Tom N4KG
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Just got a Cushcraft D40 to go on top of my Steppir at around 75'. A few
novice questions.
First, trying to tune it prior to installation. A few feet above the
ground, it's resonance is 6.8mhz, about 8feet (on one tv antenna pole) it's
resonance is 7.00 mhz when it is set per instructions to the length
indicated for 7.140 (mid-point). How high do I need to get it to get a
realiztic read on it's resonance point?
Second question, the instructions say, no foam coax for the balun, why is
this? All I had handy in my shack was RG-8x, which I think is the foam
type...
Third question, can someone send me a photo of how they re-inforced the ends
of the elements to reduce sag?
Thanks, Michael K3MH
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
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