Thinking about getting through walls with ladder line:

1. Would it be better to have the wires proceed continuously
to the tuner, without having to make connections at feed
through insulators? My understanding, generally, is that the
fewer connections the better. This means feeding the ladder
line, without break, through the wall(s), something which I
can do easily here, but I want to anticipate any arcing etc.
and the inevitable moisture in the air during rainy season
etc.

2. How should I be conceptualizing the type of RF energy in
these lines? I assume that these wires will carry something
more like "high voltage" than the usual type of electrical
energy in domestic AC lines. How far away should these ladder
line wires actually be away from everything as they go
through the wall?

3. Fishing through a bucket of old ceramic tube insulators
out in the barn I notice most are 3" long, but there are
also ones 4", 6", and even 8" long. Seems like using a long
one would keep the bare wire of the ladder line insulated
pretty well away from the walls which are just wood in this
case. Might look odd, having an 8" tube going through a 4"
wall, but it would keep the wire of the feed line many more
inches away from the wood.

4. Is the issue RF in the ladder line wire arcing to nearby
conductivity (eg. moisture on wood)? other than that there
is no conductive (metal) material in the vacinity, just wood.
I am trying to understand how to be thinking of this RF and
how best to insulate going through the wall. Mostly I will
run barefoot but might eventually have a 1 KW with a 30L-1.

Bill K6TAJ

I just noticed that these old ceramic tubes fit nicely into 1/2"
UV/PVC electrical conduit. I can make this PVC any length I want
through the wall and then also fix a ceramic tube into it at
both ends for double insulation. That ought to do it.


Bill K6TAJ

zeno wrote:

Thinking about getting through walls with ladder line:

1. Would it be better to have the wires proceed continuously
to the tuner, without having to make connections at feed
through insulators? My understanding, generally, is that the
fewer connections the better. This means feeding the ladder
line, without break, through the wall(s), something which I
can do easily here, but I want to anticipate any arcing etc.
and the inevitable moisture in the air during rainy season
etc.

2. How should I be conceptualizing the type of RF energy in
these lines? I assume that these wires will carry something
more like "high voltage" than the usual type of electrical
energy in domestic AC lines. How far away should these ladder
line wires actually be away from everything as they go
through the wall?

3. Fishing through a bucket of old ceramic tube insulators
out in the barn I notice most are 3" long, but there are
also ones 4", 6", and even 8" long. Seems like using a long
one would keep the bare wire of the ladder line insulated
pretty well away from the walls which are just wood in this
case. Might look odd, having an 8" tube going through a 4"
wall, but it would keep the wire of the feed line many more
inches away from the wood.

4. Is the issue RF in the ladder line wire arcing to nearby
conductivity (eg. moisture on wood)? other than that there
is no conductive (metal) material in the vacinity, just wood.
I am trying to understand how to be thinking of this RF and
how best to insulate going through the wall. Mostly I will
run barefoot but might eventually have a 1 KW with a 30L-1.

Bill K6TAJ

On Tue, 27 Apr 2004 19:25:49 GMT, zeno wrote:

Thinking about getting through walls with ladder line:

Hi Bill,

This is bordering on too much thinking. ;-)

1. Would it be better to have the wires proceed continuously
to the tuner, without having to make connections at feed
through insulators?

As a generalization, sure. As an instance, it will probably never
matter. The real question is how can you goof to make it matter?

Obviously by making poor connections [You don't plan to do that do
you? You aren't typically shoddy are you? Let's put that nightmare
to one side.] There will no doubt be fifteen postings pointing out
how lightning "may" melt the connections (and this, of course,
presumes many improbabilities equal in likelihood to lightning
striking).

but I want to anticipate any arcing etc.
and the inevitable moisture in the air during rainy season
etc.
which introduces:

2. How should I be conceptualizing the type of RF energy in
these lines? I assume that these wires will carry something
more like "high voltage" than the usual type of electrical
energy in domestic AC lines. How far away should these ladder
line wires actually be away from everything as they go
through the wall?

Far enough. Flash-over, arcing, and such all derive from the geometry
of the gap, barometric pressure, humidity, and such. However, just
dredge up a common circumstance of the ordinary Spark Plug and observe
the several KV it takes to leap maybe an inch?

You have to work very hard to make it happen - why would it be easier
through chance?

However, this doesn't answer the question so much as offer
perspective. Keep the ladder line as far away from anything (fill in
the blank) as it is wide. If you want, double that value for a safety
factor of two. If it won't arc across the lines, it sure won't jump
to the wall out of caprice.

SWR is a manifestation of literal Standing Waves that in turn exhibit
voltage peaks and current peaks distributed along the line between the
line leads. If you are so lucky as to have a balanced load (which
thus offers a minimum of common mode potentials), it stands to reason
you've confined your risk. Bringing nearby conductive elements into
the scheme introduces both an unbalance with a corresponding rise of
common modality. Would you hold a nail between the conductors?
Recent suggestions that little matters over the short haul mock your
sensibility to this question. Sparks occur at site dislocalities and
drawing down wide spaced, paired lines to fit through a small hole are
classic spark generators (anyone every see a jacob's ladder?). Same
thing goes for the impedance bump of a dielectric (your wall)
introduced between them coming through separate holes. In short,
jeopardy either way.

Which scenario offers more path resistance? There is no better
determiner of success. Your ceramics were made to answer that.
Basically, (and on the basis of what you have written thus far) trust
your instincts and then test.

The question is simply: how much potential resides between the two
leads at any site dislocality? Change the frequency and you have to
answer that question again. Are those holes bridging (AKA shorting) a
voltage maxima, or voltage minima of the Standing Wave? If you know
that answer, then apply that knowledge to every half wave interval
along the line all the way to (and including) the antenna and ask: is
there something nearby each or any of those points that will catch a
spark and render a flame?

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Tue, 27 Apr 2004 19:25:49 GMT, zeno wrote:

....

2. How should I be conceptualizing the type of RF energy in
these lines? I assume that these wires will carry something
more like "high voltage" than the usual type of electrical
energy in domestic AC lines. How far away should these ladder
line wires actually be away from everything as they go
through the wall?

Far enough. Flash-over, arcing, and such all derive from the geometry
of the gap, barometric pressure, humidity, and such. However, just
dredge up a common circumstance of the ordinary Spark Plug and observe
the several KV it takes to leap maybe an inch?

Ouch, Richard, that's a pretty wild shot from the hip. Spark plugs
use gaps on the order of hundredths of an inch and voltages
on the order of dozens of KV.

And for Zeno, just bring the tube out to the surface of
the wall, don't extend it... you don't want those things
breaking off!
__
Steve
KI5YG
..

Bill, K6TAJ wrote:
"Thinking about getting through walls with ladder line."

I`ve brought open wire lines through walls by Pyrex bowl insulators
mounted on a sheet of plywood framed into the wall as if it were a
window. The plywood between the conductors seemed not to hurt. Glass or
Plexiglas would be better and might obviate the bowl insulators.

You also could cut the plywood, Plexiglas, or glass sheet to fit under a
window sash. Then, just lower the sash on the sheet.

You want innocuous materials between the wires and surrounding the line
by at least several times the spacing between the wires.

Best regards, Richard Harrison, KB5WZI

Tnx to all for your thoughts. I think I am ready to go. My intuition and
gathered knowledge from this process here seems to have inspired, finally,
some confident action. I will let you know what the results are. Now with
the good weather it is time for the work.

73 Bill K6TAJ

Stephen Cowell wrote:

"Richard Clark" wrote in message
...
On Tue, 27 Apr 2004 19:25:49 GMT, zeno wrote:

...

2. How should I be conceptualizing the type of RF energy in
these lines? I assume that these wires will carry something
more like "high voltage" than the usual type of electrical
energy in domestic AC lines. How far away should these ladder
line wires actually be away from everything as they go
through the wall?

Far enough. Flash-over, arcing, and such all derive from the geometry
of the gap, barometric pressure, humidity, and such. However, just
dredge up a common circumstance of the ordinary Spark Plug and observe
the several KV it takes to leap maybe an inch?

Ouch, Richard, that's a pretty wild shot from the hip. Spark plugs
use gaps on the order of hundredths of an inch and voltages
on the order of dozens of KV.

And for Zeno, just bring the tube out to the surface of
the wall, don't extend it... you don't want those things
breaking off!
__
Steve
KI5YG
.

On Wed, 28 Apr 2004 00:52:42 GMT, " Stephen Cowell"
wrote:
dredge up a common circumstance of the ordinary Spark Plug and observe
the several KV it takes to leap maybe an inch?

Ouch, Richard, that's a pretty wild shot from the hip. Spark plugs
use gaps on the order of hundredths of an inch and voltages
on the order of dozens of KV.

Sorry you got bit there, Stephen,

It's called understatement. Besides, RF potentials have the capacity
to excite conduction above and beyond ignition spark conditions.
However, all things considered, the general breakdown tabulations
illustrate it remains fairly difficult to accomplish.

73's
Richard Clark, KB7QHC

Bill,
If you have the insulators and want to use them, why
not? Even if you have the insulators and you don't want
to use them, no problem there either. The 'dislocality',
'discontinuity', impedance 'speed bump' where the ladder
line goes through the wall just isn't going to make a lot
of difference. It would just make sense to use some kind
of nonconductive material imediately around the feed line,
but going way out of your way to do so seems a bit
excessive (all things considered). I've seen ladder line
fed through an under-eave vent, routed through an attic,
laying on 'stuff', and then through a sheet rock ceiling
via a 'slit' cut with a knife. No problems with matching
or high voltage arcing even at legal limit power levels.
As for 'connections'. Make them even 'close' to right
and there should be no problems with arcing. If you're
really worried about it, stagger the connections. I've
seen some really 'fubar' installations, but never any
arcing of the ladder line, yet... Metal backed insulation
would be my biggest 'worry, but even that wouldn't cause
any loss of sleep...
'Doc

I have used open wire feedlines in six houses so far. I drill two 3/4 inch
holes in any wall that is most convenient to bring the line inside and over
to the tuner. I ram two pieces of plastic pipe in the holes letting about an
inch or so protrude from the wall surfaces inside and outside.

When I move, I yank out the pipe, jamb stucco, wood filler and/or drywall
goo in the holes, dad paint on the repair and VOILA! Walls as good as new.

The whole thing is so easy. Why make it hard on yourselves?

73, AL

When your wire goes through the 3/4 plastic pipe, do you fill the pipe hole
with something?

I was thinking you could wrap that part of the wire with electricians tape to
make it snug and to keep bugs and water out.

Bill


Alfred Lorona wrote:

I have used open wire feedlines in six houses so far. I drill two 3/4 inch
holes in any wall that is most convenient to bring the line inside and over
to the tuner. I ram two pieces of plastic pipe in the holes letting about an
inch or so protrude from the wall surfaces inside and outside.

When I move, I yank out the pipe, jamb stucco, wood filler and/or drywall
goo in the holes, dad paint on the repair and VOILA! Walls as good as new.

The whole thing is so easy. Why make it hard on yourselves?

73, AL