[TowerTalk] Opinions please--re: 40-2CD compared to XM-240

[K7LXC@aol.com]

In a message dated 4/17/01 1:22:35 PM Pacific Daylight Time, 
qcs0041@lexcominc.net writes:

> I have had a " stock " 40-2CD Cushcraft stored for several years
>  awaiting the installation  of another 100 ft. tower. The tower work is
>  in progress now, so I 'm getting ready to do something with the antenna,
>  but now I 'm wondering whether to perform the mods that everyone
>  recommends or to just purchase a new XM-240 so I won' t have to spend
>  several days re-working the 40-2CD.  After 45 years of making and / or
>  modifying antennas, I 'm ready to take the easy way out.

    What's your county windspeed zone? If you don't know, check the TIA-222 
ratings at  <A HREF="http://www.championradio.com">Champion Radio Products</A>
 under Tech Notes. Unless you have a windspeed over 80 MPH or so, I wouldn't 
worry about beefing up the 402CD mechanicals. 

    Unless you've got ice loading, you don't need the boom truss struts IMO. 
We don't have any ice loading out here in the Pacific NW and I don't even 
install them; no boom failures in 15 years with 6-8 installations. 
>  
>  Does the XM-240 really provide the advantages that are claimed by the
>  manufacturer ?
>  --with better mechanical design, etc. ?

    Yes, but that's it - there's no "etc.". While the electrical performance 
is claimed to be the same, TowerTalkians have found otherwise. The 402CD 
could be installed within 5-6 feet of a tribander while the XM240 needs to 
have 8-10 feet at least of separation. The only electrical difference seems 
to be the fact that the reflector on the XM is insulated and it's not on the 
CD. This seems to be the obvious difference/influence but no one has checked 
it out so it's just theory at this point. 

    My recommendation is that unless you have a real compelling reason, put 
up the CD. If you're worried about the mechanical bits or have a *high* 
windspeed rating, beef up the CD. If both are true and you don't want to mess 
with the mods, then get the XM. 

Cheers,      Steve    K7LXC
Tower Tech 

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