On Thu, 17 Jun 2004 22:22:22 -0000, (Dave Platt)
wrote:

Hi Jason,

Not that at all, otherwise all of the elements would be driven, and
simple observation negates that. I've reported a similar design to
this group years ago that uses the SO-239 bulkhead connector wired up
in similar fashion: One wire extending directly from the center pin
solder tail, and another wire, parallel, soldered to any of the four
holes normally used for mounting. No need whatever for the usual
JPole tuning cap.

There's an analysis of a similar design on Cebik's web site - his
"non-standard J-pole" is a bottom-fed, non-shorted design with a
shorter-than-usual radiating section and a longer-than-usual matching
leg.

http://www.cebik.com/jp1.html


Hi Jason, Dave,

A repeat of a subset of data offered here 5 and 7 years ago from data
measured at the bench 12 years ago:

.... built up from 0.085" diameter bronze tubing. In each case, the
center connection is brought out 13 inches.... with one vertical
element that paralleled the main element with a constant separation of
0.5 inch.

The variation of the second rod is called "Match Length" in the chart

Radiator Match Fo SWR
Length Length MHz 50 Ohm

13.0 6.0 485 2.8
13.0 5.75 548 2.3
13.0 5.5 556 1.8
13.0 5.25 576 1.8 (545-630 3:1)
13.0 5.0 624.5 1.48 (575-640 2:1)
13.0 4.75 638 1.08 (640-660 2:1)

73's
Richard Clark, KB7QHC