OPEN WIRE LINE
 

After many years of experimenting with coax fed wire antennas I am
taking my first plunge at open wire line.

To get into shack, I need to go through exterior steel siding,
exterior wood siding & plywood, a layer of insulation, then interior
sheetrock and wood paneling. Assume I need about 4-6" of safe
feedthrough so that standoffs can be mounted on the walls oustide
and inside the shack.

I generally run 100 to 1500W output...at full legal limit probably
3KV on the feedline...am not crazy about the idea of setting my house
on fire due to HV arc over.

Am looking for the old style porcelain feedthrough isnulators, but so
far have not found same.

Local Home Depot has thin PVC tubing (as in sink/toilet stems), vinyl
tubing, welding rod tubes, etc. What are the dielectric properties of
these, and the high voltage breakdown voltage...???

Seems like glass, porcelain, or ceramic tubing would be best
feedthrough insulator, but where to find?

Are any modern day materials found in Lowes or Home Depot safe from
arcing and also efficient for RF?

Thanks in davance & 73,

Dan (K0DAN)

On Tue, 15 Feb 2005 21:44:34 -0600, me wrote:

After many years of experimenting with coax fed wire antennas I am
taking my first plunge at open wire line.

To get into shack, I need to go through exterior steel siding,
exterior wood siding & plywood, a layer of insulation, then interior
sheetrock and wood paneling. Assume I need about 4-6" of safe
feedthrough so that standoffs can be mounted on the walls oustide
and inside the shack.

I generally run 100 to 1500W output...at full legal limit probably
3KV on the feedline...am not crazy about the idea of setting my house
on fire due to HV arc over.

Am looking for the old style porcelain feedthrough isnulators, but so
far have not found same.

Local Home Depot has thin PVC tubing (as in sink/toilet stems), vinyl
tubing, welding rod tubes, etc. What are the dielectric properties of
these, and the high voltage breakdown voltage...???

Seems like glass, porcelain, or ceramic tubing would be best
feedthrough insulator, but where to find?

Are any modern day materials found in Lowes or Home Depot safe from
arcing and also efficient for RF?

Dear Dan,

It seems that many take the approach of using a pair of coax lines
hooked up as a balanced coax pair as the answer to that problem. If
you are worried about the impedance discontinuity, it's a short
section and will not be a problem. If you are worried about whether or
not the coax can handle it, RG-8 is good enough and RG-17 is better.
If you want to combine a little bit of protection against near strikes
while you're at it, run through the wall low to the ground and close
to the biggest, best earthing system you can put together, and then
connect the shields of the coax to a short hunk of heavy wire to that
earthing system.

Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html

There must be NO metal and NO low-grade insulating material BETWEEN the pair
of wires as they come into the shack.

Bring the wires close together for a short distance through a relatively
small hole in the wall. At HF, the small lumped increase in capacitance
between the wires will have a neglible effect on system operation.
Equivalent to an unoticeable minor shift in tuner settings. No additional
line loss will be incurred.

Insulate the pair of wires from each other by using the inner conductors of
coax cable plus the polyethylene. Discard the outer conductor braid. To
minimise size of hole through the wall allow the polyethylene coverings to
touch each other if you like.

The main problem will be rain and weather-proofing.

For a short, indoors, distance to the transmitter or tuner, the twin
polyethylene insulated wires can be retained and allowed to separate if
convenient.
---
Reg, G4FGQ

====================================

"me" wrote -
After many years of experimenting with coax fed wire antennas I am
taking my first plunge at open wire line.

To get into shack, I need to go through exterior steel siding,
exterior wood siding & plywood, a layer of insulation, then interior
sheetrock and wood paneling. Assume I need about 4-6" of safe
feedthrough so that standoffs can be mounted on the walls oustide
and inside the shack.

I generally run 100 to 1500W output...at full legal limit probably
3KV on the feedline...am not crazy about the idea of setting my house
on fire due to HV arc over.

Am looking for the old style porcelain feedthrough isnulators, but so
far have not found same.

Local Home Depot has thin PVC tubing (as in sink/toilet stems), vinyl
tubing, welding rod tubes, etc. What are the dielectric properties of
these, and the high voltage breakdown voltage...???

Seems like glass, porcelain, or ceramic tubing would be best
feedthrough insulator, but where to find?

Are any modern day materials found in Lowes or Home Depot safe from
arcing and also efficient for RF?

Thanks in davance & 73,

Dan (K0DAN)

me wrote:
Are any modern day materials found in Lowes or Home Depot safe from
arcing and also efficient for RF?

For that 6" run, just use two pieces of parallel
coax. The inside conductors are your balanced
conductors and the braids are grounded. Be sure
not to exceed the voltage rating of whatever coax
you choose to install.
--
73, Cecil http://www.qsl.net/w5dxp


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"me" wrote in message
...
After many years of experimenting with coax fed wire antennas I am
taking my first plunge at open wire line.

To get into shack, I need to go through exterior steel siding,
exterior wood siding & plywood, a layer of insulation, then interior
sheetrock and wood paneling. Assume I need about 4-6" of safe
feedthrough so that standoffs can be mounted on the walls oustide
and inside the shack.

I generally run 100 to 1500W output...at full legal limit probably
3KV on the feedline...am not crazy about the idea of setting my house
on fire due to HV arc over.

Am looking for the old style porcelain feedthrough isnulators, but so
far have not found same.

Local Home Depot has thin PVC tubing (as in sink/toilet stems), vinyl
tubing, welding rod tubes, etc. What are the dielectric properties of
these, and the high voltage breakdown voltage...???

Seems like glass, porcelain, or ceramic tubing would be best
feedthrough insulator, but where to find?

Are any modern day materials found in Lowes or Home Depot safe from
arcing and also efficient for RF?

Thanks in davance & 73,

Dan (K0DAN)

You don't by any chance have a window close at hand that you could run the
feeders through?
This really simplifies the situation. That is the way I get my feeder in and
out of the house.
Ed, N5EI




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On Tue, 15 Feb 2005 21:44:34 -0600, me wrote:

After many years of experimenting with coax fed wire antennas I am
taking my first plunge at open wire line.

To get into shack, I need to go through exterior steel siding,
exterior wood siding & plywood, a layer of insulation, then interior
sheetrock and wood paneling. Assume I need about 4-6" of safe
feedthrough so that standoffs can be mounted on the walls oustide
and inside the shack.

I generally run 100 to 1500W output...at full legal limit probably
3KV on the feedline...am not crazy about the idea of setting my house
on fire due to HV arc over.

Am looking for the old style porcelain feedthrough isnulators, but so
far have not found same.

Local Home Depot has thin PVC tubing (as in sink/toilet stems), vinyl
tubing, welding rod tubes, etc. What are the dielectric properties of
these, and the high voltage breakdown voltage...???

Seems like glass, porcelain, or ceramic tubing would be best
feedthrough insulator, but where to find?

I use ceramic feedthrough insulators on a piece of board in the bottom
of my window to bring 450-ohm line indoors. I got the insulators from
Surplus Sales of Nebraska -- you can check their web site for info;
they have a pretty good selection of NOS in all sizes, tho' they ain't
cheap.

You may do just as well rigging something else, as per some of the
other suggestions here...

bob
k5qwg


Are any modern day materials found in Lowes or Home Depot safe from
arcing and also efficient for RF?

Thanks in davance & 73,

Dan (K0DAN)

Excellent idea...I can envision a couple N or UHF connectors on either
side of the wall, and the entry point is indeed near the ground system
so that too is feasible. Thanks for the tip...there are others coming
in but this sounds very feasible and relatively easy!
73
Dan
K0DAN

On Wed, 16 Feb 2005 04:31:15 GMT, (Robert
Lay) wrote:

On Tue, 15 Feb 2005 21:44:34 -0600, me wrote:

After many years of experimenting with coax fed wire antennas I am
taking my first plunge at open wire line.

To get into shack, I need to go through exterior steel siding,
exterior wood siding & plywood, a layer of insulation, then interior
sheetrock and wood paneling. Assume I need about 4-6" of safe
feedthrough so that standoffs can be mounted on the walls oustide
and inside the shack.

I generally run 100 to 1500W output...at full legal limit probably
3KV on the feedline...am not crazy about the idea of setting my house
on fire due to HV arc over.

Am looking for the old style porcelain feedthrough isnulators, but so
far have not found same.

Local Home Depot has thin PVC tubing (as in sink/toilet stems), vinyl
tubing, welding rod tubes, etc. What are the dielectric properties of
these, and the high voltage breakdown voltage...???

Seems like glass, porcelain, or ceramic tubing would be best
feedthrough insulator, but where to find?

Are any modern day materials found in Lowes or Home Depot safe from
arcing and also efficient for RF?

Dear Dan,

It seems that many take the approach of using a pair of coax lines
hooked up as a balanced coax pair as the answer to that problem. If
you are worried about the impedance discontinuity, it's a short
section and will not be a problem. If you are worried about whether or
not the coax can handle it, RG-8 is good enough and RG-17 is better.
If you want to combine a little bit of protection against near strikes
while you're at it, run through the wall low to the ground and close
to the biggest, best earthing system you can put together, and then
connect the shields of the coax to a short hunk of heavy wire to that
earthing system.

Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html

Thanks for the tip Reg...yours is vote #2 for some sort of coax
transition, and I like this approach as it sounds feasible and easy
(and inexpensive). Am looking forward to a a couple more days of good
WX to complete the antenna project! Many thanks and 73
Dan (K0DAN)

On Wed, 16 Feb 2005 05:06:29 +0000 (UTC), "Reg Edwards"
wrote:

There must be NO metal and NO low-grade insulating material BETWEEN the pair
of wires as they come into the shack.

Bring the wires close together for a short distance through a relatively
small hole in the wall. At HF, the small lumped increase in capacitance
between the wires will have a neglible effect on system operation.
Equivalent to an unoticeable minor shift in tuner settings. No additional
line loss will be incurred.

Insulate the pair of wires from each other by using the inner conductors of
coax cable plus the polyethylene. Discard the outer conductor braid. To
minimise size of hole through the wall allow the polyethylene coverings to
touch each other if you like.

The main problem will be rain and weather-proofing.

For a short, indoors, distance to the transmitter or tuner, the twin
polyethylene insulated wires can be retained and allowed to separate if
convenient.
---
Reg, G4FGQ

====================================

"me" wrote -
After many years of experimenting with coax fed wire antennas I am
taking my first plunge at open wire line.

To get into shack, I need to go through exterior steel siding,
exterior wood siding & plywood, a layer of insulation, then interior
sheetrock and wood paneling. Assume I need about 4-6" of safe
feedthrough so that standoffs can be mounted on the walls oustide
and inside the shack.

I generally run 100 to 1500W output...at full legal limit probably
3KV on the feedline...am not crazy about the idea of setting my house
on fire due to HV arc over.

Am looking for the old style porcelain feedthrough isnulators, but so
far have not found same.

Local Home Depot has thin PVC tubing (as in sink/toilet stems), vinyl
tubing, welding rod tubes, etc. What are the dielectric properties of
these, and the high voltage breakdown voltage...???

Seems like glass, porcelain, or ceramic tubing would be best
feedthrough insulator, but where to find?

Are any modern day materials found in Lowes or Home Depot safe from
arcing and also efficient for RF?

Thanks in davance & 73,

Dan (K0DAN)

Hi Cecil...

Vote #3 for the coax feedthrough...sounds like this trick is well
known and escaped all my reading.

Thanks and 73
Dan (K0DAN)

On Wed, 16 Feb 2005 00:01:08 -0600, Cecil Moore
wrote:

me wrote:
Are any modern day materials found in Lowes or Home Depot safe from
arcing and also efficient for RF?

For that 6" run, just use two pieces of parallel
coax. The inside conductors are your balanced
conductors and the braids are grounded. Be sure
not to exceed the voltage rating of whatever coax
you choose to install.

Ed...

Nope, the window is not feasible. There is an awning type window with
metal frame but its location and installation make it unfeasible.
Penetrating the wall nearby, however, is feasible, and the recent tips
to use coax as the feedthrough medium sound really good.
Thanks for your reply, this antenna should be operational soon!
73
Dan
K0DAN


On Wed, 16 Feb 2005 06:55:11 -0500, "Edward A. Feustel"
wrote:


"me" wrote in message
.. .
After many years of experimenting with coax fed wire antennas I am
taking my first plunge at open wire line.

To get into shack, I need to go through exterior steel siding,
exterior wood siding & plywood, a layer of insulation, then interior
sheetrock and wood paneling. Assume I need about 4-6" of safe
feedthrough so that standoffs can be mounted on the walls oustide
and inside the shack.

I generally run 100 to 1500W output...at full legal limit probably
3KV on the feedline...am not crazy about the idea of setting my house
on fire due to HV arc over.

Am looking for the old style porcelain feedthrough isnulators, but so
far have not found same.

Local Home Depot has thin PVC tubing (as in sink/toilet stems), vinyl
tubing, welding rod tubes, etc. What are the dielectric properties of
these, and the high voltage breakdown voltage...???

Seems like glass, porcelain, or ceramic tubing would be best
feedthrough insulator, but where to find?

Are any modern day materials found in Lowes or Home Depot safe from
arcing and also efficient for RF?

Thanks in davance & 73,

Dan (K0DAN)

You don't by any chance have a window close at hand that you could run the
feeders through?
This really simplifies the situation. That is the way I get my feeder in and
out of the house.
Ed, N5EI




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