Here's what I'm doing and I'd like some feedback.

Antenna will be an 88ft doublet 30-40ft high supported at the center by
a ladderlock and fed by 450ohm windowline. The windowline will drop
down to within 8ft of the ground (above kiddie reach) where it will be
connected to a W2DU style choke balun based on RG213 and Palomar BA-8
ferrites. This will be enclosed in a ~12" length of electical conduit
which will be supported to relieve the windowline of further strain.

The coax will connect at the bottom of the choke enclosure via
PL259/SO239 to a ~10ft length of RG213 down to earth level driploop and
up into a small lockable mushroom enclosure containing a ICE300
supported on a 5/8"x8ft copper ground rod. Also contained in the
enclosure will be an LDG RT-11 tuner which will be mounted on the
backside of the ground rod from the ICE300. A small RG213 jumper will
connect the ICE and RT. The shell of the shielded DB-9 control line
will have a small braid to bond it to the ground mounting point as
well.

The coax and shielded DB-9 control lines from the RT will drop out of
the enclosure via PVC conduit to an undergound PVC junction box which
has it's bottom side perforated to drain any condensate. The run to the
house from this JB is ~50ft with a 1ft rise which should ensure a flow
of any condensate to the JB drain. The RG213 will be direct burial
grade but I've not been able to find any shielded DB-9 direct burial
cable hence the electrical PVC conduit.

At the house end the PVC will sweep up to another small enclosure atop
another 5/8"x8ft ground rod holding a grounding point for the shells of
the coax and control lines and also will terminate the line from the
station bond from inside the shack. The lines will then enter the house
through a driploop and travel ~5ft to the shack.

At the shack a ground bus will be provided where each of the pieces of
equipment will be bonded individually. This ground bus will be
connected via a 3" copper strap 5ft back out to the ground rod at the
entrance to the house.

The station ground outside the house is 40ft away from the service
entrance and its ground. I'm thinking of running "something" from the
station ground rod to the service entrance. I can easily periodically
"terminate" this with some intermediate ground rods if necessary along
its length.

What should the "something" running between the station and service
ground rods be?

How often should any periodic termination rods be added?

Any help on direct burial shielded DB-9 cable?

tnx
jtm

wrote:

Here's what I'm doing and I'd like some feedback.

Antenna will be an 88ft doublet 30-40ft high supported at the center by
a ladderlock and fed by 450ohm windowline. The windowline will drop
down to within 8ft of the ground (above kiddie reach) where it will be
connected to a W2DU style choke balun based on RG213 and Palomar BA-8
ferrites. This will be enclosed in a ~12" length of electical conduit
which will be supported to relieve the windowline of further strain.

The coax will connect at the bottom of the choke enclosure via
PL259/SO239 to a ~10ft length of RG213 down to earth level driploop and
up into a small lockable mushroom enclosure containing a ICE300
supported on a 5/8"x8ft copper ground rod. Also contained in the
enclosure will be an LDG RT-11 tuner which will be mounted on the
backside of the ground rod from the ICE300. A small RG213 jumper will
connect the ICE and RT. The shell of the shielded DB-9 control line
will have a small braid to bond it to the ground mounting point as
well.

Assuming you are going to use this system on 20m, EZNEC says
the 10' piece coax will see 166-j960 ohms for an SWR in excess
of 100:1. Depending upon where the voltage antinodes are located
and how much power you are running, that may be enough to cause
arcing at the coax connectors.

Why not run the ladder-line all the way to the tuner? Hint: SGC
says not to tie transmission line to the outputs of their SG-230.
--
73, Cecil http://www.qsl.net/w5dxp


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

Hi Cecil

Output power for my use will never exceed 100W, more typically 5W or
less. The RT-11 is only rated to 125W. But your caution on impedance is
just the sort of feedback I was looking for. I was considering running
the windowline all the way to the ground but was concerned about the
neighbors' kids getting their hands on it. My alternative was to run a
bit of conduit upwards to shelter the windowline until it was out of
reach, ~8ft. I was concerned however about how large such a PVC conduit
would need to be to avoid problems with the windowline. Would 2" be big
enough since its non-conducting?

tnx
jtm

wrote
Here's what I'm doing and I'd like some feedback.

Antenna will be an 88ft doublet 30-40ft high supported at the center by
a ladderlock and fed by 450ohm windowline. The windowline will drop
down to within 8ft of the ground (above kiddie reach) where it will be
connected to a W2DU style choke balun based on RG213 and Palomar BA-8
ferrites. This will be enclosed in a ~12" length of electical conduit
which will be supported to relieve the windowline of further strain.

The coax will connect at the bottom of the choke enclosure via
PL259/SO239 to a ~10ft length of RG213 down to earth level driploop and
up into a small lockable mushroom enclosure containing a ICE300
supported on a 5/8"x8ft copper ground rod. Also contained in the
enclosure will be an LDG RT-11 tuner which will be mounted on the
backside of the ground rod from the ICE300. A small RG213 jumper will
connect the ICE and RT. The shell of the shielded DB-9 control line
will have a small braid to bond it to the ground mounting point as
well.

The coax and shielded DB-9 control lines from the RT will drop out of
the enclosure via PVC conduit to an undergound PVC junction box which
has it's bottom side perforated to drain any condensate. The run to the
house from this JB is ~50ft with a 1ft rise which should ensure a flow
of any condensate to the JB drain. The RG213 will be direct burial
grade but I've not been able to find any shielded DB-9 direct burial
cable hence the electrical PVC conduit.

At the house end the PVC will sweep up to another small enclosure atop
another 5/8"x8ft ground rod holding a grounding point for the shells of
the coax and control lines and also will terminate the line from the
station bond from inside the shack. The lines will then enter the house
through a driploop and travel ~5ft to the shack.

At the shack a ground bus will be provided where each of the pieces of
equipment will be bonded individually. This ground bus will be
connected via a 3" copper strap 5ft back out to the ground rod at the
entrance to the house.

The station ground outside the house is 40ft away from the service
entrance and its ground. I'm thinking of running "something" from the
station ground rod to the service entrance. I can easily periodically
"terminate" this with some intermediate ground rods if necessary along
its length.

What should the "something" running between the station and service
ground rods be?

How often should any periodic termination rods be added?

Any help on direct burial shielded DB-9 cable?

tnx
jtm


Jim, if you use twin-lead from choke-to-tuner as Cecil suggested, the coax
arrestor model at the tuner can be changed to ICE-304U per
http://www.arraysolutions.com/Produc...mpulse1.html#2

40' is at least 2x too long for a bonding jumper, according to a PE's
interpretation of NEC-70/NFPA-780. That leaves up to you what to do to
mitigate this problem. Practically speaking, you can not provide a low
impedance connection that far no matter what conductor was used. But
compared to the home's AC ground wiring which is outrageously high
impedance, you can provide reasonable equipotential with the service ground.
A minimum of one 8' copper clad ground rod, driven 10' into the ground every
2x rod depth feet is the code requirement for grounding electrodes. Applying
that electrode-length requirement to a distance too long for a bonding
jumper is not defined in the code, hence the professional opinion that was
required in my case, which I share with you. In that similar situation, I
used 4' copper ground rods every 8' along the bonding-path to the service
entrance. The risk involved with such a long jumper is Ground Potential
Rise. This could draw current from the station ground up into the bonded
equipment cases, overpowering the withstand design of the equipment, and
exiting the equipment via the AC connections and coax feedlines. As long as
you provide a bond that is significantly lower impedance than the AC wiring
to the service ground, you have minimized GPR-risk. Not eliminated it. The
better the bonding and voltage-division your ground system provides
(radials, improved service entrance ground, ground rings, ufer-grounds, etc)
the more protection from GPR you provide. Your bonding must be capable of
balancing the GPR across the entire system. Since the withstand of most
equipment is approximately 2,000v, you should not have a problem maintaining
a much lower potential than that.

The only other thing I would add, is an ICE-300 on the equipment ground
bus-bar, after first shield-grounding the coax feedline at the station
single point ground.

73,
Jack Painter
Virginia Beach, Virginia

Hi Jack

I missed something in the above: you said an 8ft rod driven 10ft into
the ground? Does that mean the top of the rod is buried 2ft?

Then driving such a rod every 2x rod depth feet would mean one every
20ft vs every 16ft?

What would be the recommended connecting conductor between all the
points? Big honking cable or copper strapping?

I haven't purchased the ICE unit yet until I had gotten some feedback
so making that change is no problem.

So you would suggest two ICE units? One at the antenna base and another
at the station ground?

BTW, I'm wondering if any installation has ever met the codes you cited
other than a dedicated broadcast transmitting facility. Certainly would
be the exceptional (1%) residence in my experience.

thanks for your help!

jtm

"Jim Miller" wrote
Hi Jack

I missed something in the above: you said an 8ft rod driven 10ft into
the ground? Does that mean the top of the rod is buried 2ft?

Then driving such a rod every 2x rod depth feet would mean one every
20ft vs every 16ft?

What would be the recommended connecting conductor between all the
points? Big honking cable or copper strapping?

I haven't purchased the ICE unit yet until I had gotten some feedback
so making that change is no problem.

So you would suggest two ICE units? One at the antenna base and another
at the station ground?

BTW, I'm wondering if any installation has ever met the codes you cited
other than a dedicated broadcast transmitting facility. Certainly would
be the exceptional (1%) residence in my experience.

thanks for your help!

jtm


Hi Jim, I was quoting from the fire and electrical codes regarding grounding
electrodes, and yes they mean buried 2' beneath ground surface to reach a
total depth of 10'. Use the length of the rod in the ground, not rod depth
when determining spacing. That confusing aspect came about when 10' rods
were going to be maintained as the minimum length allowed, and contractors
screamed they could not obtain them (cheaply). So the 8' rod buried to a
depth of 10' was born.

Use 16' as the spacing between buried 8' rods.

Recommend minimum #4 copper or heavier for the service entrance to station
bonding connector. It does not have to be continuous if intermittent-spaced
ground rods are used. If you figure out some way to efficiently trench for
6" deep 26ga copper strap, please let me know - that would be ideal. Strap
is also difficult to bond to ground rods, and generally too thin for
exothermal (cadweld) connections.

As for using two coax lightning arrestors, that might rarely if ever be
specified. Normally the shield-grounding along the tower and at station
entrance is sufficient that one arrestor either on the master ground bus or
right outside at the 1st ground rod would suffice. But you are trying to
protect your external tuner (let us know how that works out ) and might
permit some voltages the receiver front-end doesn't like, should they be
induced or shorted from shield-to-conductor along the feedline path.

As far as meeting electrical codes and fire standards for grounding systems,
there is no way around that in my opinion. If your home is going to be
protected from loss by insurance, then you either need to meet all codes and
standards, or else somehow demonstrate that you isolate all systems safely
before the risk of loss occurs. Personally I don't know how most amateur
operators ever collect for lightning damage, since examination by forensic
(fire) investigators could show failure to meet code and/or best industry
practices in most cases. Yes, you are a "broadcast station" wrt lightning,
and in an area subject to it, should take appropriate measures to either
always be isolated before the risk occurs, or withstand the risk by plan and
design. Proper isolation is not just tossing the feedline out the window as
so many unfortunately believe. Considering the risk involved if proper
isolation is not followed, protecting the whole property seems like a better
plan to me.

73,
Jack

Hi Jack

Just got back from HomeDepot where they had 5/8"x8' copper rod and
bronze clamps as well as #2 copper wire. I'll use two bronze clamps on
each so I can daisy chain the #2. I can put one on the corner of the
house and two more along the way to the service ground. That will make
four including the station ground around the house and one out at the
antenna tuner.

Thanks for your help

jtm (risk averse...)

On Wed, 2 Mar 2005 13:23:25 -0500, "Jack Painter"
wrote:





Hi Jim, I was quoting from the fire and electrical codes regarding grounding
electrodes, and yes they mean buried 2' beneath ground surface to reach a
total depth of 10'. Use the length of the rod in the ground, not rod depth
when determining spacing. That confusing aspect came about when 10' rods
were going to be maintained as the minimum length allowed, and contractors
screamed they could not obtain them (cheaply). So the 8' rod buried to a
depth of 10' was born.

Jack, isn't this getting a little over-the-top? I have to dig a 2
foot hole, get an 8 foot rod totally buried in that hole -- and then
what, to bond different rods together, dig a 2 foot trench from rod to
rod to bond them together with strapping?

And what about all the corrosion on the buried rods and strapping?

Who does this sort of stuff !! ??

I understand you're quoting from codes, but does anyone "residential"
really do this stuff?

bob
kj5qwg

"Bob Miller" wrote
On Wed, 2 Mar 2005 13:23:25 -0500, "Jack Painter"
wrote:


Hi Jim, I was quoting from the fire and electrical codes regarding
grounding
electrodes, and yes they mean buried 2' beneath ground surface to reach a
total depth of 10'. Use the length of the rod in the ground, not rod
depth
when determining spacing. That confusing aspect came about when 10' rods
were going to be maintained as the minimum length allowed, and
contractors
screamed they could not obtain them (cheaply). So the 8' rod buried to a
depth of 10' was born.

Jack, isn't this getting a little over-the-top? I have to dig a 2
foot hole, get an 8 foot rod totally buried in that hole -- and then
what, to bond different rods together, dig a 2 foot trench from rod to
rod to bond them together with strapping?

And what about all the corrosion on the buried rods and strapping?

Who does this sort of stuff !! ??

I understand you're quoting from codes, but does anyone "residential"
really do this stuff?

bob
kj5qwg

Hi Bob, you're right few people follow NEC code to any degree unless an
inspector is going to follow. And I hope I pointed out a couple examples
where code was changed or written because of convenience, not science (the
2' below grade level and non-continuous requirement). So in some cases
following code is not the best practice (it needs to be exceeded) and in
other cases is just not practical or possible. You be your own judge there.
Anyone who follows the topic knows why the rules are there, and that in the
case of a casualty, an investigation may assign blame whether code was
followed or not, but certainly if it was not.

The knowledge gained and effort made to protect property is certainly more
important than splitting hairs about code that is a moot point for most.

73,

Jack Painter
Virginia Beach, Virginia

Jim Miller wrote:
Hi Cecil

Output power for my use will never exceed 100W, more typically 5W or
less. The RT-11 is only rated to 125W. But your caution on impedance is
just the sort of feedback I was looking for. I was considering running
the windowline all the way to the ground but was concerned about the
neighbors' kids getting their hands on it.

Look at the bright side - you could teach them something about
the physics of RF. :-)

My alternative was to run a
bit of conduit upwards to shelter the windowline until it was out of
reach, ~8ft. I was concerned however about how large such a PVC conduit
would need to be to avoid problems with the windowline. Would 2" be big
enough since its non-conducting?

If the PVC is kept away from conductors, 2" should be just fine.
--
73, Cecil http://www.qsl.net/w5dxp

----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----