I did some work on this conversion in 1990 for the late Jim Rafferty, N6JR.
I don't know if Jim ever did finished building it before he died.
I modeled the 3 element on a 33 foot boom using the same hardware as the
rest of the beam. As I recall, the gain was not very much greater (perhaps
1 dB) than the 2 element 40-2CD but the pattern improved quite a bit (as do
most Yagis on a 1/4 WL boom). Also, the VSWR degraded. One big problem with
this design is that the Q of the coils is so-so at best so adding another
element with the same coils also sees additional loss. I think they will
still sell them as replacement parts through customer service.
At 09:50 PM 2/16/2003 -0500, W0YR@aol.com wrote:
>Does anyone have experience with converting a 2 element Cushcraft 40 Meter
>yagi to a 3 el antenna. Did you buy/build the coils? Spacing that worked
>for u? Results?
>F/B Gain results? Bandwidth?
>Antennaware mailing list