I disagree with K7LXC's comment re: 40M element. I have used an A-4 with 40
M element since 1985. It's at 55 ft and it plays like gangbusters compared
to a 40M dipole.
The key is the rotatability and the null off the ends of it, not the gain.
Of course it doesn't have the gain of a dipole, but these other two
attributes more than make up for that. It's not gain that you need, it's
the ability to point the antenna at the station you're talking to (or trying
to talk to) and provide some rejection in the other directions. A single
fixed dipole just don't do that (except in two directions). Especially if
you don't have the supports for multiple horizontal dipoles and a switching
arrangement for them!
If you have an A-3 or A-4 you already have the rotating base for the 40M
element. If you then have the space to rotate it, it works FB! (My
experience only).
By the way, the Cushcraft catalog specifies the sq ft wind load of the 40M
kit. I don't remember what it is right now.
73!
Bill, N3RR
PS: I have NO affilliation or other relationship with Cushcraft or any other
antenna manufacturer. These comments are my own opinion based upon my
experiences.
Bill
At 03:02 PM 2/8/96 -0500, K7LXC@aol.com wrote:
>In a message dated 96-02-08 13:45:52 EST, you write:
>
>> How do you determine the sq. ft. wind load of an
>>antenna? I have a Cushcraft A3, and I'm thinking of adding a 40m kit to it
>>when it goes up (probably this summer). I can't find anything in the
>>specifications that defines the wind load.
>>
>>Is there some simple calculation for this? This this the aerodynamic flat
>>plate equivalent?
>>
>>Thanks.
>>
>>Bill Coleman, AA4LR
>
>Hiya, Bill --
>
> There's a long answer and a short answer. The long answer is to get Dr.
>Dave Leeson's (W6QHS) book on yagi design and crank through cylindrical
>multisection modulus, moment and other various calculations. The short
>answer is to get the manufacturer's catalog -- it'll be listed in the specs.
> If you want one publication that has all of the antennas, rotators plus
>various other products complete specs, pick up a copy of the CQ Antenna
>Buyer's Guide; it's a good reference for lots of specs. Contact your local
>dealer or call CQ direct for the latest copy.
>
> Regarding the Cushcraft 40M add-on kit, it's got negative gain compared to
>a dipole; put up the dipole instead if possible.
>
>
>73, Steve K7LXC
>
> "Up The Tower" now appears in CQ Contest magazine
>
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