COPPER Colinear Design Comments:

   Date: Mon, 23 Aug 1999 22:58:55 -0500
   From: richard.tindall@email.riverwood.com

In reference to your 2 meter collinear J-Pole,  one question.   What is the
distance between the 19" and 57" and between the two 18" pieces when the
antenna is complete.

KD5GVK
 

  Date: Tue, 24 Aug 1999 11:55:06 -0400
  To:  richard.tindall@email.riverwood.com

Richard,
After you assemble everything, try to make the two 18" pieces parallel.  Butt
the ends of the elbow and tee pieces right up against each other before you
solder them together.  The distance is not as important as the 18" elements are
at a 90-degree angle to the other larger elements and run parallel to each
other.  The same thing goes for the 19" element.  I know this sounds like a lot
of double talk.  I did not make an exact measurement.  What matters most is
that the spacing distance should be equal and even from one end to the other.
Hope this answers your question.
Steve  KB1DIG


   Date: Sun, 20 Jun 1999 00:40:04 -0500
   From: "Mickey O. Haynes" <bigmac77@mtco.com>

hi i spent the day building the stacked jpole--the half wave version--i
was wondering if you have any thoughts on the performance of the 5/8
wave version vs. the 1/2 wave version.  Is it worth trying the latter?
Any thoughts ? Also I'm looking for ways to stack multiple waves on top
of each other but i haven't figured out how many times an antenna can be
stacked without cancelling out the gain.
 

    Date:  Sun, 20 Jun 1999 08:57:07 -0400
    To: "Mickey O. Haynes" <bigmac77@mtco.com>

Mickey,

Did you do the "Copper" or the "PVC" verson?

 "performance of the 5/8 wave version vs. the 1/2 wave version."  The 5/8x2
one I did out performed the "Copper" 1/2x2 wave.  This was very noticeable
when I asked for comparisons from distant stations.  Say, approximately 20
miles away, using simplex.

"how many times an antenna can be stacked without canceling out the gain."
As far as what I've read in the ARRL Antenna Book you can do up to 4 stacked
1/2 wave elements.  Theoretically you could do more, but more then 4
elements are rarely used because of the size and how to support it
(impractical).  Small secondary lobes appear in the pattern when more then 2
elements are used, but the amplitudes of these lobes are low enough so that
they are not important.  From my own experience, if you try stack more then
2 of the 1/2 wave elements, the antenna may become more narrow banded,
unless everything is exact and in phase.  I did read somewhere about
stacking several 1/4 wave elements, but I don't recall the method.  This
1/4x wave system is supposed to work really good...

Good Luck!

Steve  KB1DIG
 

   Date: Mon, 21 Jun 1999 00:30:34 -0500
   From: "Mickey Haynes" <bigmac77@mtco.com>

I built the half wave version of the jpole and stacked it twice my receive
signal jumped about 3 s meter units with each stack but I'm having swr
problems.  I followed the directions on the dimensions but the antenna
seemed to resonate on about 140 megahertz. The swr didn't drop below 2 to 1
anywhere. When I adjusted it, I had it away from any metal and about 10 feet
in the air. Do you know of any other ways to set the swr--like changing the
dimensions perhaps?  Where would I start? I was hoping to master the stacked
halfwave before attempting the 5/8 wave version. Oh yeah-the swr was high
before adding the stacking element, and the stacking element didn't make the
swr higher--it just made it slightly more narrow banded with each of the
stacks. Also I was thinking of the possibility of using phasing coils on a
stacked vertical but I can't seem to find any info on the construction of
such devices or how to use them. I need a vertical with about 10db of gain.
Thanks .
 

   Date: Mon, 21 Jun 1999 18:43:22 -0400
   To: Mickey Haynes <bigmac77@mtco.com>

 Mickey,

I am still unclear as to what type of antenna you are building.  Are you making
it from "copper tubing" or "wire inside of PVC"?

What is the transmit power level you are using?

I don't know if you will ever reach the 10db gain level in this manner.

Also, something to consider; what is the best way to connect your feed line to a
multiple element antenna greater then 2 elements?  From what I've read the best
way would be from the center and with a 4:1 balun.

Steve  KB1DIG
 

   Date: Mon, 21 Jun 1999 20:50:27 -0500
   From: "Mickey Haynes" <bigmac77@mtco.com>

Hi, what I am doing right now is building the copper jpole 1/2 wave stacked.
I've stacked it 2 times and it seems to work good. However, I am having
slight swr problems. The swr was 2 to 1 across 2 meters.
I'm not exactly sure what to do about this--except change dimensions of it.
I am not really sure what dimension to change first though. Any ideas? I am
also looking for plans on any other sort of vertical with a high amount of
gain. Do you have any ideas on anything to build that might have up to 10db?
 

  Date: Tue, 22 Jun 1999 18:12:01 -0400
  To: Mickey Haynes <bigmac77@mtco.com>

Mickey

Did you build this copper j-pole using the design I made?

Did you try changing the feed point up and down between the 1/4 wave matching
section?

If you have a center frequency of 140.000Mhz the best place to start is to
shorten the upper 1/2 wave element.  Try a around 1/4 inch at a time.

Steve  KB1DIG
 

   Date: Tue, 22 Jun 1999 19:39:47 -0500
   From: "Mickey Haynes" <bigmac77@mtco.com>

I built the antenna using that exact model. I changed the feedpoint to
adjust the swr.  So now I will go ahead and shorten the halfwave element to
increase its resonant frequency.