[CQ-Contest] Patching YT.EXE

Straw, Dean, N6BV rdstraw at arrl.org
Mon Sep 8 15:42:00 EDT 1997

Patching YT.EXE
Sep 08, 1997

This patch removes a very subtle bug in YT.EXE Version 1.0, and
creates a Version 1.1. Thanks to K4AB for pointing the problem
out. The bug shows up only in certain complex terrains, where
diffraction points may not be visible from different Yagis in a
stack and where the antenna heights are specified by the operator
in an "upside down" fashion.

For example, if your stack has Yagis at 90 and 50 feet, it's
possible that the 50-foot-high Yagi can't "see" certain
diffraction points because they are shadowed by your particular
terrain, while the higher Yagi at 90 feet can see the diffraction
point directly. If you specify the heights as #1 = 90 and #2 = 50
feet (that is, the "normal" method, meaning that's the way I do
it!), everything is OK. But if you specify them as #1 = 50 and #2
= 90 feet, the bug may show up. You can overlay the two scenarios
together to see if the two computations line up exactly, as they

If you find that your terrain exhibits the bug in YT, then e-mail
n6bv at arrl.org for a copy of the zipped patch file.


Dean Straw, N6BV
Senior Assistant Technical Editor, ARRL
n6bv at arrl.org

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