Stryped wrote:
"I am making a J-pole out of 1/2 inch conduit."

There ia a 144 MHz Super-J in the "ARRL Antenna Book". It`s on page
16-24 of my 19th edition. Individual piece drawings and measurements
are presented for novice builders.

The "Antenna Book" Maritime Antenna is "Super" because it is a collinear
using (2) 1/2-wave sections, in phase, and end to end. For a simple
J-pole, eliminate one 1/2-wave section and the 1/4-wave phase-inverting
stub.

Stainless steel is used fotr the "Super J-pole", but rustable steel can
be used if deesired.

Best regards, Richard Harrison, KB5WZI