unbalancing open wire feeders

[N3DRB The Derb]

heres the deal: I have 2 pvc pipes going from inside to outside the house. One has a cable tv (RG-6) line going through it, length maybe 3~4 inches long, the other has the ground system wires going through it. maybe #000 at that point.  They break out to stranded #6 with soldered split nut connections on both inside and out.

?: if I feed one wire of the 600 ohm W7FG feeders through he 3~4 inches next to the ground will it unbalance the line to be noticeable enough on the air or make the stealth edition matchbox break a sweat trying to tune the thing?  I could drill 2 more holes in the house but I'm trying not to. if I have to do it I will.

might be one of those ?s that cant be answered until you try it? Thought I would ask anyway.

[Pete, WA2CWA]

The balanced lines should not be next to anything metallic, coax cables, etc. You would be defeating the purpose of a balanced line.

[Ralph W3GL]

Tim,

Yeah, what he said!

[N3DRB The Derb]

yeah, but just 3 to 4 inches worth?  Thats really enough to unbalance the line?

alternative: I could feed 450 ohm line out one of the holes without anything in it ( I'd pull the cable for the cable tv out) and join it up to the other W7FG 600 ohm line outside. I presume that would be better. There would be a small bump in the line of course but I'm presuming the tuner would handle that OK. The ladder line is much easier to handle inside the house.

To feed the W7FG antenna in the house requires drilling 2  1 1/2" more holes in the house. I can do it ok, but it's a hassle.

[Mike/W8BAC]

Tim,

I installed a W7FG 80 meter doublet here 6 years ago. I use bee hived feed threw assemblies here and I haven't had a single problem. Rain, snow, wind, winter or summer the performance is predictably the same.

My feed line runs very close to aluminum siding for some 20 feet with no ill effects wet or dry. You can expect similar results.

Going threw that PVC might be a problem BUT like you said

might be one of those ?s that cant be answered until you try it?

it might not. If the spacing is close to the 600 ohm standard just give it a try.

Be aware the failure event could be heat and smoke, or worse. I would advise a bee hived all thread feed threw.

[Ralph W3GL]

Timmy,

A short run of that 450 ohm crappy brown stuff will be fine...

The posability of fire and smoke is there if the close (3 to 4 inch)
association is near a voltage max on the line.  Don't take a chance...

The big flash box should be very happy working into the 450 stuff
and you will still be balanced.

[N3DRB The Derb]

10-4. I got to go through that big assed switch MOP gave me, that will make a nice changeover point from 450 to 600.

[Tim WA1HnyLR]

Hi Derb,
 Having a short run 6-8"of one side of the open wire feed system should not materially effect anything when it comes to imbalancing the line.If you are concerned in any way simply take two equal lengths of coass .Run each length through the PVC pipe . Tie the braids together at each end. If the Junkston flashbox is located close to the area of exit tie the braids to the ground stud on the flashbox . Tie your ground wire to the braids on the outside . SLather on the Goop to seal up the somebitch.
De Tim WA1HnyLR

[Ralph W3GL]

Yeah, as Tim says, Coax works too ifen you want to mess with it but if the 450 line will pass through the unobstructed tube, go for it!

[W3RSW]

yeah, then if you want to keep it centered and sealed too, try a can of foam insulation stuff you spray into elect. boxes for wind proofing, like whipped cream that rises. -  test it out for conductivity first though. don't want a short. ho,ho.