Alternate material j pole and questions about dimensions
 

I am experimenting making a j pole out of 1/2 inch conduit. What I am
thinking of doing is making it like a "u" in that each piece, the
radiator, stub and shorting bar are cut at 45 degree angles and welded
togther. I have the dimensions using the 1/2 inch copper. How do i
measure each pieces "length"? I mean in the copper plan they use t
fittings and measure the radiator length starting incide the t fitting
where it is lower than the shorting bar.

My ides was to just measure the end of the angled piece where I cut it
to the top, but not sure if this is right. What do you think?

Also, since an antenna constructed this way will not have an "extended
leg" to mount to a mast, would it be acceptable to mount the shorted
horizontal section to the mast? Will this cause problems?
Any help is appreciated. I hope to work on this tomorrow.

On 21 Jan 2005 05:37:58 -0800, wrote:

I am experimenting making a j pole out of 1/2 inch conduit. What I am
thinking of doing is making it like a "u" in that each piece, the
radiator, stub and shorting bar are cut at 45 degree angles and welded
togther. I have the dimensions using the 1/2 inch copper. How do i
measure each pieces "length"? I mean in the copper plan they use t
fittings and measure the radiator length starting incide the t fitting
where it is lower than the shorting bar.

My ides was to just measure the end of the angled piece where I cut it
to the top, but not sure if this is right. What do you think?

Also, since an antenna constructed this way will not have an "extended
leg" to mount to a mast, would it be acceptable to mount the shorted
horizontal section to the mast? Will this cause problems?
Any help is appreciated. I hope to work on this tomorrow.

Best method is to cut the length slightly over, then test on an SWR
meter, and trim a little at a time to optimize.

Different materials, different wall thickness, and different diameter
will all affect the apparent electrical length.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom