[TowerTalk] Fwd: [PVRC] SY-3 3 Element yagi dimensions?

[Haring family]

Tom,

Ok, those lengths are just the cut-lengths for the tips ONLY. So... it
might not be too bad. Here's what I did using a NEC 2 engine and AutoEZ:

For each side:
16mm: 1200mm exposed (well, that includes the boom radius for each side)
12mm: 1200mm exposed

height: 3500mm... pretty low...
aluminum
Real/Hi Acc gnd/Avg (.005,13)
AGT Factor = .999>>should be a good model

In the absence of impedance design targets and to ensure the model didn't
go crazy, I aimed for about 25+jY feed.

With the small dimensions, I did not make any corrections for the clamp at
the boom.

[azimuth plot removed because of size]

I ended up with:

417mm reflector tip length,
349mm de tip length, and
103mm director tip length.

The lengths they gave in the manual were just for the tip lengths, and I
don't see nearly the difference between reflector and DE as they had. But
they assuredly had different optimization ideas... I aimed for r~25, Gain
and F/B.

I didn't do anything on the gamma match.

It's tempting to see if you can find some feedback on the internet, and
hear how well it feeds and performs.

regards,

Dave N3AC