From Newsgroup: sci.electronics.design

I've got a length of RG213u that wants to exit the house and then turn upwards to a roofmounted antenna.

For practical reasons, I suspect it should, instead, turn downwards (driploop) before heading up. Regardless, I can't exit the wall parallel to the soil
and then "suddenly" take a sharp bend (up, down or sideways) -- minimum bend radius is ~4.5".

So, the bend has to start *inside* the wall.

What are best practices, in this regard? Run a PVC elbow through the wall
and then snake the cable through that? Let the drip loop sit against the
outer surface of the wall and turn upwards in that same plane? Mount the lightning arrester *there*, above the loop?

And, is it best to route the cable "exposed" vs. hiding it in interior walls? --- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On Thu, 14 Aug 2025 12:51:08 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

I've got a length of RG213u that wants to exit the house and then turn upwards >to a roofmounted antenna.

For practical reasons, I suspect it should, instead, turn downwards (driploop) >before heading up. Regardless, I can't exit the wall parallel to the soil >and then "suddenly" take a sharp bend (up, down or sideways) -- minimum bend >radius is ~4.5".

So, the bend has to start *inside* the wall.

What are best practices, in this regard? Run a PVC elbow through the wall >and then snake the cable through that? Let the drip loop sit against the >outer surface of the wall and turn upwards in that same plane? Mount the >lightning arrester *there*, above the loop?

And, is it best to route the cable "exposed" vs. hiding it in interior walls?

Start with how to handle a lightning strike.

Joe
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From Newsgroup: sci.electronics.design

On 8/14/2025 2:23 PM, Joe Gwinn wrote:

On Thu, 14 Aug 2025 12:51:08 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

I've got a length of RG213u that wants to exit the house and then turn upwards
to a roofmounted antenna.

For practical reasons, I suspect it should, instead, turn downwards (driploop)
before heading up. Regardless, I can't exit the wall parallel to the soil >> and then "suddenly" take a sharp bend (up, down or sideways) -- minimum bend >> radius is ~4.5".

So, the bend has to start *inside* the wall.

What are best practices, in this regard? Run a PVC elbow through the wall >> and then snake the cable through that? Let the drip loop sit against the
outer surface of the wall and turn upwards in that same plane? Mount the
lightning arrester *there*, above the loop?

And, is it best to route the cable "exposed" vs. hiding it in interior walls?

Start with how to handle a lightning strike.

The Code addresses that. But, doesn't address cosmetic and other
"practical" issues.

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From Newsgroup: sci.electronics.design

On 14/08/2025 20:51, Don Y wrote:

I've got a length of RG213u that wants to exit the house and then turn upwards
to a roofmounted antenna.

For practical reasons, I suspect it should, instead, turn downwards (driploop)
before heading up.-a Regardless, I can't exit the wall parallel to the soil and then "suddenly" take a sharp bend (up, down or sideways) -- minimum
bend
radius is ~4.5".

So, the bend has to start *inside* the wall.

Why so?

It should be acceptable to make most of the curve exterior to the wall
and just have it stick out a bit.

BTW Do you really need a drip loop in a desert?
A rain shield might be easier.

Where I live it is mandatory because it rains so much, but penetrating
damp doesn't sound very plausible as a serious problem in Arizona.

I prefer to stay at least 2x minimum bend radius for coax YMMV.

What are best practices, in this regard?-a Run a PVC elbow through the wall and then snake the cable through that?-a Let the drip loop sit against the outer surface of the wall and turn upwards in that same plane?-a Mount the lightning arrester *there*, above the loop?

My experience of lightning arresters - even high end ones on chunky
copper busbars that are *supposed* to protect mainframes is that against
a direct building hit they are useless.

The magnetic induced currents in local wiring loops are so unpredictable
and the protection devices save themselves by letting the most expensive terminal concentrator IO boards to fry to a crisp. All of it needed
replacing. I was sorely tempted *not* to replace the "protectors".

And, is it best to route the cable "exposed" vs. hiding it in interior walls?

Take it to the outside at 45 degrees with a downward slope if you must
and then curl it back up the wall. Depending on your skill with a cold
chisel you can alter the exit angle if you really want to do that.
--
Martin Brown

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From Newsgroup: sci.electronics.design

On 8/19/2025 1:10 PM, Martin Brown wrote:

On 14/08/2025 20:51, Don Y wrote:

I've got a length of RG213u that wants to exit the house and then turn upwards
to a roofmounted antenna.

For practical reasons, I suspect it should, instead, turn downwards (driploop)
before heading up.-a Regardless, I can't exit the wall parallel to the soil >> and then "suddenly" take a sharp bend (up, down or sideways) -- minimum bend >> radius is ~4.5".

So, the bend has to start *inside* the wall.

Why so?

Relatively large bend radius. Can't force a tighter bend. And, having something sticking out ~5 inches is kind of low class.

It should be acceptable to make most of the curve exterior to the wall and just
have it stick out a bit.

BTW Do you really need a drip loop in a desert?

During Monsoon, we have really intense rains with high winds. For example,
I have "lowered" the center of the back yard by a full foot to provide a
place for the rainwater to accumulate *as* it settles into the soil. This fills in relatively short order and then we start wondering if additional accumulation will backup onto the porch and against the house.

A rain shield might be easier.

Where I live it is mandatory because it rains so much, but penetrating damp doesn't sound very plausible as a serious problem in Arizona.

I prefer to stay at least 2x minimum bend radius for coax YMMV.

That would bring the 4.5" to 9".

Walls are typically "concrete block" (not flimsy "cement block") so reasonably hard to drill. (I use an oversized SDS hammer drill for such tasks as encountering bits of gravel in the concrete makes "household" masonary bits useless)

What are best practices, in this regard?-a Run a PVC elbow through the wall >> and then snake the cable through that?-a Let the drip loop sit against the >> outer surface of the wall and turn upwards in that same plane?-a Mount the >> lightning arrester *there*, above the loop?

My experience of lightning arresters - even high end ones on chunky copper busbars that are *supposed* to protect mainframes is that against a direct building hit they are useless.

The ground typically does most of its protective work eliminating static
build up. Direct strikes are a lost cause -- except to towers (where the
tower itself can shunt most of the strike directly to ground.

But, I have to anticipate deployments in the types of occupancies that
the code *requires* lightning protection (not required for residences).

The magnetic induced currents in local wiring loops are so unpredictable and the protection devices save themselves by letting the most expensive terminal
concentrator IO boards to fry to a crisp. All of it needed replacing. I was sorely tempted *not* to replace the "protectors".

When I lived in Denver, we had a nearby (?) strike that managed to fry the protection network in the electronic telephone we had. And, left the TV's color field distorted for dozens of degaussing cycles! I never went looking for signs of where the strike may have been.

As a kid, I recall a strike within 20 ft of our rooftop antenna (a large
walnut tree) as evidenced by the missing bark down the side of the tree!
But, aside from the loudness of the strike -- and the simultaneous
flash and bang -- there was no other damage to the house's contents
(there, power and phone were routed through the air; here, all are below grade)

And, is it best to route the cable "exposed" vs. hiding it in interior walls?

Take it to the outside at 45 degrees with a downward slope if you must and then
curl it back up the wall. Depending on your skill with a cold chisel you can alter the exit angle if you really want to do that.

Getting that "downward angle" is part of the challenge as the cable will likely run *in* an interior wall until it reaches the exterior block wall. (No attics nor basements, here -- such fun!) Unless there is a compelling reason (?) to leaving it "exposed", I prefer hiding it.

[I've gone to great lengths to hide everything in and on the house as doing otherwise really looks tacky. E.g., seeing CATV feeds come up a wall,
across the roof and down another wall where they bore through the exterior
wall to locate the jack immediately inside. Even painted, it is an
obvious afterthought!]

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