At 08:28 PM 10/19/2005, N4BAA - Jose Castillo wrote:
>Cort...
>
>Hello...well...well...as I am a purist....and LOVE the old KLM
>BIG STICKERS...I have several here at N4BAA QTH.....I have spoken
>with Mike Staal at M2 who designed them and YES...you can
>optimize them a LITTLE...but only to increase the gain by about
>.31 dbd ..NOT FOR ME...
>
>Jose Castillo - N4BAA
Actually I think optimizing them with modern NEC-based tools is worth
the effort, especially if you really want to achieve the promise of the
dual-driven elements. While you won't get a lot more gain, what you
can get is more bandwidth, especially for the VSWR and the F/B specs.
When I did the optimization a number of years ago I kept the DE spacing
the same so I could use the original phasing line and also forced the feed
impedance to 200 ohms so that a 4-1 balun would work. In my case I am
a big believer in coax-based 4-1 baluns.
Upon optimization the big gap in directors was reduced to something that
LOOKED better. Performance seemed better, especially F/B at the
ends of the band. And, something that is important to all Alpha owners,
the VSWR bandwidth was greatly improved. So ALL things got better and
some things got much better.
Now for the problem. I have no idea where the data is at the moment with
so much stuff packed away. But I will start looking for some info on the
new dimensions at least and then anyone can play. I am sure that someone
can do somewhat better if the DE spacing is allowed to change, but I didn't
want to have to "dink" with new phasing lines.
73 -- John W0UN
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