[TowerTalk] more questions

[K7LXC]

In a message dated 98-04-26 11:28:38 EDT, k1my@nlis.net writes:

> I'm thinking of:
>  
>  90 foot Rohn 45 tower
>  40 meter beam
>  KT34XA
>  wire on 80 & 160
>  
>  
>  1. For the 40 meters, I have a choice. Would you go with 3 element KLM or
>  Cushcraft 2 element 402CD? If the 3 element KLM, some (KJ6Y & W7ZRC)are
>  saying that the KT34XA tribander likes to be on top with parallel booms;
>  that would be ~ 90+ feet with the 40 meters about 10 feet below it at about
>  80 feet. I don't know. Is the extra db worth it?  Do you have any comment
>  on what should go on top? 

     Over the years I've had 3-4 KLM 40M yagis from 2L to the 4L 'big one'. I
got rid of all of them, installed the 402CD and I've never regretted it. The
4L KLM never played like you'd think an antenna that size would - it never
really acted like a monobander - and the Cushcraft works great for it's size. 

     But my decison was based more on mechanical considerations than
performance. The KLM's are fragile and the bigger they are, the more they
break. I prefer the CC because it's simpler and more reliable - I don't have
to take it down every summer and repair it. 

     I prefer having the bigger antennas on the bottom. Since they'll require
more maintenance, it's just easier to get them down for repair if they're on
the bottom. There may be something to be said for a bigger antenna 'shading'
antennas below it but I don't have anything scientific to back that up. 
>  
>  2. Or should I just stick with the beefed up Cushcraft? If 402CD & KT34XA,
>  who is on top? KLM says spacing is OK at 8 feet or more.
>  The one on top will be on a mast rotated with a T2X. The lower one will be
>  on a ring rotor. 402CD on top?

      CC is FB with me. Beefed-up is good. From a windload standpoint since
the CC has less square footage, that may be the one to put on top.

     The XA and 402CD is a classic little gun set-up. They both work well and
are very competitive. 

      Here's a thought. If you want to REALLY go nuts on 40M, put up a 2-stack
of 402CD's. You can turn the bottom one with a Ham IV and you get the same
approximate gain of a full-sized 3L plus a big fat low angle lobe although
your 90 foot tower might not be tall enough. It would be worth modeling. You
could space them like it was a big quad loop - that might work. Anyway, worth
considering.

Cheers,  Steve  K7LXC

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