Jim Brown wrote:
> As I proceed with building a 15M yagi, K6RM pointed me to G0KSC's OWA
> design, and K5RC noted that he likes the design. As I study G0KSC's
> website, I like it too, and note that he suggests the use of 15mm
> plexiglass as an insulator for 50 MHz and 70 MHz Yagis. One slick
> thing about the OWA design is that element lengths and spacings are
> tweaked so that it matches directly to 50 ohms. YW says 1.25 VSWR
> worst case over the band, 8.1 dBi gain over the band, >21dB F/R.
>
> My elements (from a neighboring Silent Key's boneyard) will probably
> all be 0.875-inch at the center (tapering to 5/8-inch), except that
> the driven element might be 1-inch tapering to 3/4-inch. What do you
> think? Would Plexiglass or Lexan be sufficiently robust? I'm thinking
> of drilling holes in it just like one would do with an Aluminum plate
> for two pairs of u-bolts, one to hold the element and the other to
> hold the plate to the 2-inch boom. Any other suggestions?
>
I'd not use plain U-bolts, but rather saddle clamps which give a much
more solid mount.
Lexan is very robust and I use it for a number of things including
center insulators, but at 1/4" and thicker it is very expensive and I
don't think I'd trust it for element to boom, or boom to mast clamps
except on VHF and UHF antennas.
73
Roger (K8RI)
> 73,
>
> Jim K9YC
>
>
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