Running dipole feed line through copper tubing j-pole.

[K5JMN]

Hello all:
I haven't seen this scenario posted: I am considering using a twin-band J-pole constructed out of 3/4 copper tubing as a center support for a HF multi-band inverted V dipole. My question is - is there any issue with running the dipole coax through the J-pole? It seems like it would not affect the J-pole since the j-pole RF is via skin effect on the outside of the tubing. Likewise, it seems the dipole would be unaffected because the shielded/grounded coax would just be traveling though Metal conduit.

 

[Ubbe]

The tip of a J-pole are high impedance and are extremely sensitive to any metal objects, or even wood, so keep the antenna away from any other objects.

/Ubbe

 

[bharvey2]

Common mode current on the coaxial feedline attached to a J-Pole is very prevalent. In effect, that make the feedline part of the antenna. In short, it radiates RF energy. As Ubbe stated, the J-Pole antenna system is very sensitive to adjacent objects. You'll more than likely encounter problems running the coax through the antenna's copper or any other conduit for that matter.

 

[K5JMN]

Well - s**t. I thought I was on to something.

 

[bharvey2]

Well - s**t. I thought I was on to something.

Yeah that's kind of how it goes. The rare whiz kid may come up with something new once in a while but for the rest of us, we're just trying to reinvent the wheel.

 

[AK9R]

The rare whiz kid may come up with something new once in a while but for the rest of us, we're just trying to reinvent the wheel.

But, if you don't know that the guy in the next cave already invented the wheel, it doesn't hurt to ask.

 

[bharvey2]

But, if you don't know that the guy in the next cave already invented the wheel, it doesn't hurt to ask.

Very true. My comment wasn't meant to be a sleight to the O.P. I can't tell you how many times I've seen my cave dwelling neighbors with shiny new wheels!

 

[K5JMN]

Very true!
I've tested and got my Extra but have a LOT of catching up to do. Got my tech (novice?) Back in 87 but other shiny things captured my interest and never did anything with it. Never even got a simple radio for CW - could be had for about 50 bucks around then. Let it expire in 2007.
Fast forward 12 years and my brother is encouraging me to get back in plus I gain a son-in-law who has his Extra. Ok! Finally decided to go for it about 3 months ago. Studied for 2 or 3 weeks and got my General. Studied till the next session (4 weeks) and got my Extra.
Still don't have my first radio. (Got a Boafeng but don't really count that) Learning all I can in prep for my first rig around November. Trying to figure out how to work HF on my 83 x 85 lot while keeping the wife happy. 🤨
Yes sir - a LOT of catching up to do.

 

[RadioDXfun]

I never felt to reinvent the wheel personally, I go with simple as that seems to suit me. Others like to experiment and that is commendable, more so if you actually home brew the antennas, not just model them. However, I always tried to implement the wheels already made as well as I possibly can. And I feel I have really benefited from that. 1/4, 1/2, 5/8 all work very well (surprisingly well in some cases) when you have made and tested the variants and tried different mounting heights. Where practical anyway. There are pros and cons with the above 3 simple verticals and you work out what one works best for your QTH.

In short what I found is for 1/4 and 1/2 the ground is your enemy (so get it high !), for the 5/8 it is your friend.

When set up and built well all 3 of these work as advertised. Even putting in surprisingly good performances at times, in weak conditions.

The thing with a mono band vertical is you have the vertical DX gold standard performance for that band. That counts for a lot, much more than some realize. Weak conditions let you know what a really good antenna is and is not. A good antenna makes contacts in weak conditions, a poor antenna makes you turn your radio off and go to do some other jobs.

 

[K5JMN]

If I were to use something like a DX Commander and raise the base up to roof height, is there a solution to implementing the radials?

 

[RadioDXfun]

It is interesting you mention that as he had a video about installing a Hex beam that I stumbled on recently. You should check it out.

As far as DX Commander it might be best to drop him a line as I have never used one I am sure he knows the most about his product. As far as I see most have them on the ground. As they are a kind of multi-band 1/4 wave, elevating the radials may mean they need to be resonant (and possibly best at 45 degrees sloping down like a traditional mono band 1/4 wave) as they part company with earth below, not sure how that would work for a multiband antenna. That would move away from just a set of long-ish 30-60 random length ones that capacitively couple to the ground surface or buried under the ground as in typical ground mount install.

It is likely that elevating it may introduce some difficult to quantify tuning effects, band by band.

 

[tomhobbs]

Good luck with your purchase of a radio. I was out of a radio for about a year and found the Yaesu FT-991A to be what I preferred. There is the Icom 7300, Yaesu FT450D. and many others. The best rig for you is one that has the bells and whistles you want. That being said, spend GOOD money on your antenna. Try making one. Grab the S-I-L and the 2 of you make and test one. If it works to what you like make another. As for the DX Commander, do drop him a line. He is real good on getting back to fellow hams. Hope to see you on the radio soon.