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Positioning a Helix feed



Hello all,

I'm trying to position a new helical feed (with the coffee
"cup"), and tried using a diode noise generator attached to
my HT.  It worked, but there was no repeatability to the
positioning.  Very small movements of the HT (held by my
daughter), dish, etc. caused very big changes in my S-meter.

How should I position the Helix?  My thoughts:

1) go with the best, but imprecise, position using the
noise generator.  Use a vice if needed to keep things
steady.

2) Position by measurement.  I saw a reference on this
BB that the typical MMDS dipole feed was at 12" from
the grill.  If correct, position the end of the first
turn at 12" (assuming the Phase Focus discussion
concluded that correctly).  Note that this isn't where
the first process put it (a few inches different)

3) Cover the dish temporarily with tin foil, and shine
a light on it (or use the sun).  Position helix at
maximum brightness.  Can I assume the focus for light
and 2.4 ghz will be in the same place?

What do you think?

Thanks,

Greg  KO6TH

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