[TowerTalk] RE: 40M Yagi recommendations
n4kg@juno.com
n4kg@juno.com
Wed, 24 Nov 1999 06:07:14 -0600
I love my CC 402CD at 95 ft. It plays VERY well on CW and
has required NO maintenance in the 4 or 5 years it's been up.
On SSB it "feels" less competitive. Others have reported
better SSB performance using "intermediate" element settings.
My understanding of the differences between it and the XM-240
are that the reflector of the XM-240 is insulated from the boom
while the 402CD reflector is electrically connected to the boom.
This alledgedly improves the pattern and may account for the
differences in interaction when stacked with tribanders. One
solution might be to simply ground the reflector at the boom.
Another possibility is that the Driven Element is resonant at
some HF frequency due to the particular reactance from the
feedline. The feedline can be detuned by changinging it's
load at the antenna switch (open vs. closed) or changing
it's length.
The XM240 is rated for 100 MPH winds while my calculations
showed the elements of the 402CD would fold around 72? MPH
I believe this was achieved by double walling the inner sections
of the elements and going to a 2.5 inch boom vs. 2 inch for the
original antenna.
W6QHS wrote an article in QST on upgrading the mechanical
integrity of the 402CD to two different wind velocities, (100 and
125 MPH if memory serves me correctly). He also recommended
replacing the sheet metal screws in the loading coils with stainless
steel bolts, nuts, and lock washers.
I wrote an article for the NCJ (National Contest Journal) which
described a simplified upgrade where I double walled the first
section of tubing in each element and reinforced the boom ends
and center with 1-7/8 inch dowel. The antenna survived a mini-
tornado that took out dozens of trees in my woods including a
75 year old Oak and 75 year old Beech. Estimated winds were
80 to 90 MPH.
W9RE sells an upgrade kit for reinforcing the CC 402CD.
de Tom N4KG
........................
On Wed, 24 Nov 1999 10:55:25 +0100 Jan.E.Holm@telia.se writes:
>
>
> Think the W9 is W9RE / de SM2EKM
> -------------------------------------------------------------------
>
> > Look a little deeper into the issue. The "older
> > one" (40-2CD) is not
> > the same as the XM240. There have been reports here
> > on TT of the CC
> > XM240 not being a worthy successor.
> >
> > I have a 40-2CD and love it, but I would probably go
> > with a F12 if I
> > had to chose between it and a CC XM240.
>
> 40-2CD was electrically a good antenna but the
> mechanical part was lousy. The Upgrade available from
> a W9.... ( dont remember) is a must.
> 73 Rag
>
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