Another Aerial Question

[W3SLK]

I guess there seems to be a run on antenna questions so I'll keep the string going. I'm contemplating using balanced feed line to my aerial as opposed to the coax (RG-213 mil-spec) stuff I'm using now. Since I'm too lazy and have gobs of it around, I'm going to use the 450 Ù ladder line. My problem is going out the shack to the aerial. I'm currently using a piece of 2" stainless steel pipe, (very similar to what we use at work) as a conduit to the outside with a gob of electrical stuffer to keep the critters out. My question is would I be ok using a piece of 1½" PVC inside the 2" and using the same stuffer without too much of an impedance bump at HF frequencies? I'm not sure what the RF characteristics of the stuffer is but its the typical crap you would find at Home De-Pot or (How) Lowes (can you goes?). Thanks for the help.

[KF1Z]

Some people use a double run of coax to get out of the house with....

use the 2 centers for the feed, and tie the shields together...

[Steve - WB3HUZ]

You want to maintain approximately spacing of no less than 2x the ladder conductor spacing to any other metal objects. An impedance bump won't be your problem most likely, since the tuner will take care of it, but rather any loss or arcing that might occur.

[WD8BIL]

What Steve said plus.... if the pipe is 8 to 12 feet long resonance will be a problem at 10/12 meters.

[W3SLK]

The pipe is only about ~8" long. I was/am going to run the ladder line through the PVC pipe to avoid contact with the S.S. pipe. (ie PVC pipe inside the S.S. pipe). My greatest issue is with the stuffer and how conductive it is at RF potential. I would still like to keep the critters out. The thing with two pieces of coax is doable and might be a nice alternative to all the issues.

[Steve - WB3HUZ]

What's the possibility of just using a PVC pipe and no metal pipe?

The pipe is only about ~8" long. I was/am going to run the ladder line through the PVC pipe to avoid contact with the S.S. pipe. (ie PVC pipe inside the S.S. pipe). My greatest issue is with the stuffer and how conductive it is at RF potential. I would still like to keep the critters out. The thing with two pieces of coax is doable and might be a nice alternative to all the issues.

[WA1GFZ]

you want to stay away from metal with open wire line.
I used 3 thick layers of teflon tubing on 1/4 20 threaded rod to go to the wall when the shack was in my son's room. now I use a basement window with plexiglass pane.

[W3SLK]

Steve asked:

What's the possibility of just using a PVC pipe and no metal pipe?

The metal pipe was permantly installed when the house was built. I could remove it but it would make that side of the house look like crap.

[WU2D]

SLK,

I would stick with a good brand of double shielded RG-8 sized coax like RG-213 and feed it through the pipe with a control cable and put a remotey controlled tuner outside.

This would give you the best of both worlds, unbalanced where that makes sense from a safety, TVI and loss standpoint, and balanced where it does the most good.

If this is a manual tuner, this is a pain ... Hi.

Mike WU2D