Antenna Ladder Line

[W3SLK]

I have a boat load of the 450Ω ladder line and would like to use it for a diaper pole I'm planning on putting up this week. My question is that I have a two inch hole with a piece of 2" stainless schedule 10 pipe going out from my basement to the outer world. I'm curious as to the effects of running the ladder line through the pipe. I may even suspend it in the center with some 'Great Stuff' foam. Youins with the modeling programs maybe able to tell me a little more details. The pipe is only about 4" long and not ground to anything. All responses are greatly appreciated.

[Vortex Joe - N3IBX]

Mike(y),
          I don't have any antenna modeling programmes, but would like to take a shot at answering your query. I have my ladderline suspended from a 6' steel rod that was a birdfeeder in my backyard. I did this to prevent it from touching the ground. I tied the ladderline off with a piece of rope about 4 to 6 inches away from the steel rod. I've never had any arcing problems or anything that disturbed the VSWR, etc.

I don't clame to be the oracle of feedline knowledge, but I'd venture to say as long as you had it insulated, as previously mentioned; you won't run into any difficulty.

BTW, September is almost here. That means it's just right around the corner to have some good 160M QSO's. The band has been surprisingly good lately, in spite of the time of year it is. Let us all know how you made out with the antenna at the new "W3SLK Studios", and what configuration you were able to hang it in.

I'm looking forward to talking to you on the radio, and need a "Mike(y) fix" something terrible!
Mod-U-Later,
                 Joe Cro N3IBX

[K1JJ]

That's a tough question, Mike.

It's a matter of degree. Yes, there will be SOME effect, but how much, and will it be noticable?

It will depend upon whether the metal pipe is near a currrent point or voltage point on each band. A high voltage point is higher impedance and more susceptible to causing an imbalance on  the line.

I think the line is about 2" spacing and will be in a 2" metal pipe for a 4" span ? So the normal  2 diameter spacing is out. And the metal pipe will be real close for a few inches.

My gut feeling is that you would never notice the difference on the air, but you still want to be sure what's really happening. The only real way to tell is put a pair of current meters in line with the open line at the rig ... OR use a pair of little 6V flashlight bulbs across EACH individual leg and look for an inbalance.

To test it right you would first need to run the line clear of the metal pipe, like out the window and insulated from any metal. Then put it through the pipe and look for differences in balance readings. Do this on various bands to get a mix of high and low impedance points thru the pipe. That will tell ya.

But again, I think the effect will be minimal on the lower bands, and maybe measureable on the higher bands... but that's just a guess being so many variables involved. Measure it to be sure, OM.

Better yet, just replace the metal pipe with PVC, as it should be, and be done with it...

BTW, I couldn't remember if it is spelled "inbalance" or "imbalance". A quick search of "inbalance" on Google returned:   "inbalance, Thumbnail. inbalance. noun, the opposite of balance preferred by people
who can't spell."  HA!

73,
T

[WA1GFZ]

Early JN days I ran feeders out the window and found the storm windows would effect things if closer than a couple inches. I remember using a hunk of wood stuffed between the window and sill.