"JB" wrote in message
...

"Gary Pewitt" wrote in message
...
Here's a simple question. I want to connect my transceiver to several
antennas using 450 ohm ladder line and a balanced tuner. I found a
couple of small double pole double throw knife switches for the ladder
line. There are only two ways to hook these up. I can hook the tuner
output to the center with the ground on the bottom and the antenna on
the top connectors. This will allow me to connect the transceiver to
the antenna or to ground. The second way is to connect the
transceiver to the top contacts, the antenna to the center, and ground
to the bottom contacts. This will let me connect the antenna to the
radio or to ground. Is it better to ground the radio and let the
antenna float? Or to ground the antenna and let the radio float?
Of course if I leave the switch handle sticking straight up nothing is
connected to anything.
I am inclined to think grounding the antenna is better but I have been
wrong before.

Thanks and 73 Gary N9ZSV

If you have a real problem with lightning in your area, do some reading on
the situation. You might drastically redesign your grounding situation.
The
grounding should be tied together at the service entrance, so the antenna
entrance should be near there and all tied together with low resistance to
ground. This means the tuner should be there too or at the antenna The
radio should be grounded to the entrance also. It is important that all
grounding should be done outside the building rather than through the
floor.
That would bring the major current of a strike through your house. There
are ARRL tis documents on the subject and a bunch of others.


You will also want to dispense with the switches and use lightning arresters
so you won't be hanging onto several thousand volts built up on the switch.

I guess I wasn't too clear. I wanted to use one switch each for two
ladder line lead ins. Since no one I can find makes arrestors for
ladder line I am building my own from spark plugs threaded into a big
copper plate which is grounded with copper strap to 5 ground rods in a
fairly small circle outside the shack window. It's about 70 ft to the
200 amp service box from the bedroom I am using for my shack.
I just won a bid on ech bay for a double throw make before break knife
switch which I'll be using also. I'm going to buy one of those MFJ
window lead through plates with multiple ladder line connectors or
maybe make my own version.
I am wondering, instead of using just two spark plugs, if it might be
more effective to use 3 pairs in line with the first pair having
really wide gaps, the second having a medium gap, and the third having
a small gap around .035"? I am going to enclose them to keep them dry
and they will be grounded to the same rods as everything else.
I'll also have a Drake R-8 receiver in my bedroom hooked to an
Evesdropper trap dipole with a Zap Trap arrestor on the co-ax. It's
too far to run a ground to the other end of the house so I plan to
ground it outside of my window. I know that's not the best way but I
don't want to run an 80 foot ground cable to the shack ground.
Thanks for all the good advice. 73 Gary N9ZSV




On Sat, 11 Oct 2008 22:12:20 -0500, Gary Pewitt
wrote:

Here's a simple question. I want to connect my transceiver to several
antennas using 450 ohm ladder line and a balanced tuner. I found a
couple of small double pole double throw knife switches for the ladder
line. There are only two ways to hook these up. I can hook the tuner
output to the center with the ground on the bottom and the antenna on
the top connectors. This will allow me to connect the transceiver to
the antenna or to ground. The second way is to connect the
transceiver to the top contacts, the antenna to the center, and ground
to the bottom contacts. This will let me connect the antenna to the
radio or to ground. Is it better to ground the radio and let the
antenna float? Or to ground the antenna and let the radio float?
Of course if I leave the switch handle sticking straight up nothing is
connected to anything.
I am inclined to think grounding the antenna is better but I have been
wrong before.

Thanks and 73 Gary N9ZSV

Gary,
The 'spark gap' type arrestor is about the most worthless you could
possibly use. More than one reason for that, the simplest being that
by the time it ever bridges that 'gap', it's already gotten to the
radio (path of least resistance). Diverting 'some' of that lightning
strike is probably better than none though, maybe. Good luck.
- 'Doc

Doc, what else can you use for ladder line? Everything I've found is
for co-ax only. Parallel two co-ax arrestors?
I definetly want to run open line as I am going to have a long run to
the antennas. I live on a 29 acre heavily wooded 100 foot hill top in
western Arkansas so I have lots of room for -big- antennas but can
only afford homemade wire designs.
Thanks and 73 Gary N9ZSV




On Tue, 21 Oct 2008 17:03:33 -0700 (PDT), wrote:

Gary,
The 'spark gap' type arrestor is about the most worthless you could
possibly use. More than one reason for that, the simplest being that
by the time it ever bridges that 'gap', it's already gotten to the
radio (path of least resistance). Diverting 'some' of that lightning
strike is probably better than none though, maybe. Good luck.
- 'Doc

On Tue, 21 Oct 2008 17:03:33 -0700 (PDT), wrote:

Gary,
The 'spark gap' type arrestor is about the most worthless you could
possibly use. More than one reason for that, the simplest being that
by the time it ever bridges that 'gap', it's already gotten to the
radio (path of least resistance). Diverting 'some' of that lightning
strike is probably better than none though, maybe. Good luck.
- 'Doc


It is also dependant on what kind of equipment is connected as well.
If it is just a Rx, a Telco type would be appropriate. If a high
power Tx perhaps an electric service entrance type would be more
appropriate.

I know that's not the best way but I
don't want to run an 80 foot ground cable to the shack ground.
Thanks for all the good advice. 73 Gary N9ZSV


I see why you want to ground close to the shack for your single point
ground. This is good. But you will then have two grounds. One being the
ground outside your window and the other being the service entrance ground
with all the "green wire" grounds connected to it (the 3rd conductor in all
your ac line cords). When there is a strike there WILL be a potential
difference between these two grounds. That means for those few microseconds
they will NOT act as one ground and therefore there will be currents flowing
between these two points. You don't want this happening. The NEC code
requires you to bond your external grounds together, meaning you should run
a conductor outside your house from the shack ground to the service entrance
ground. It is a good idea to install ground rods every 16 feet along this
run. And the same conductor should be connected to any tower ground you
have as well.
There's tons of information on this subect. The antenna email reflector
archives is a good one, as well as the QST series about 4-5 years ago.
I know you don't want to do it, but the purpose of that 80 feet of wire is
important. Without it, all of your other work could be for naught.

Rick K2XT

Rick wrote:
I know that's not the best way but I
don't want to run an 80 foot ground cable to the shack ground.
Thanks for all the good advice. 73 Gary N9ZSV


I see why you want to ground close to the shack for your single point
ground. This is good. But you will then have two grounds. One being the
ground outside your window and the other being the service entrance ground
with all the "green wire" grounds connected to it (the 3rd conductor in all
your ac line cords). When there is a strike there WILL be a potential
difference between these two grounds. That means for those few microseconds
they will NOT act as one ground and therefore there will be currents flowing
between these two points. You don't want this happening. The NEC code
requires you to bond your external grounds together, meaning you should run
a conductor outside your house from the shack ground to the service entrance
ground. It is a good idea to install ground rods every 16 feet along this
run.

It's not clear why you'd need ground rods along your NEC bonding jumper.
If you're trying to make it do double duty as part of a grounding
ring, maybe? But then, it's the "grounding electrode", and can't serve
as the jumper.

Depending on the distance, too, the bonding wire's not going to help
with the microseconds of transient (as the transient propagates down
that bonding wire)...

Electrical safety ground (green wire) is one thing, Lightning
dissipation is another, and common reference potential is yet another.
The first two have to be connected because of NEC. The first and third
are usually connected because of coax connectors with the shield
connected to the chassis.

But in terms of minimizing transient damage to your equipment, whether
or not it happens to be grounded isn't as important as whether all the
equipment goes up and down together. You could put it all in a metal
cage and suspend it from an insulator and let lightning hit it, without
problems. (people do this for HV measurements on tesla coils and EMP
testing)




And the same conductor should be connected to any tower ground you
have as well.



There's tons of information on this subect. The antenna email reflector
archives is a good one, as well as the QST series about 4-5 years ago.
I know you don't want to do it, but the purpose of that 80 feet of wire is
important. Without it, all of your other work could be for naught.

Rick K2XT

On Tue, 21 Oct 2008 18:45:59 -0500, Gary Pewitt
wrote:


I guess I wasn't too clear. I wanted to use one switch each for two
ladder line lead ins. Since no one I can find makes arrestors for
ladder line I am building my own from spark plugs threaded into a big
copper plate which is grounded with copper strap to 5 ground rods in a
fairly small circle outside the shack window. It's about 70 ft to the
200 amp service box from the bedroom I am using for my shack.
I just won a bid on ech bay for a double throw make before break knife
switch which I'll be using also. I'm going to buy one of those MFJ
window lead through plates with multiple ladder line connectors or
maybe make my own version.
I am wondering, instead of using just two spark plugs, if it might be
more effective to use 3 pairs in line with the first pair having
really wide gaps, the second having a medium gap, and the third having
a small gap around .035"? I am going to enclose them to keep them dry
and they will be grounded to the same rods as everything else.
I'll also have a Drake R-8 receiver in my bedroom hooked to an
Evesdropper trap dipole with a Zap Trap arrestor on the co-ax. It's
too far to run a ground to the other end of the house so I plan to
ground it outside of my window. I know that's not the best way but I
don't want to run an 80 foot ground cable to the shack ground.
Thanks for all the good advice. 73 Gary N9ZSV




On Sat, 11 Oct 2008 22:12:20 -0500, Gary Pewitt
wrote:

Here's a simple question. I want to connect my transceiver to several
antennas using 450 ohm ladder line and a balanced tuner. I found a
couple of small double pole double throw knife switches for the ladder
line. There are only two ways to hook these up. I can hook the tuner
output to the center with the ground on the bottom and the antenna on
the top connectors. This will allow me to connect the transceiver to
the antenna or to ground. The second way is to connect the
transceiver to the top contacts, the antenna to the center, and ground
to the bottom contacts. This will let me connect the antenna to the
radio or to ground. Is it better to ground the radio and let the
antenna float? Or to ground the antenna and let the radio float?
Of course if I leave the switch handle sticking straight up nothing is
connected to anything.
I am inclined to think grounding the antenna is better but I have been
wrong before.

Thanks and 73 Gary N9ZSV

There is an alternative. Run a #2/0 (67.4 mm^2) bare copper buried 1
foot (300 mm) below grade between them. Bit of a pain, but bonds the
two grounds right proper.

Gary Pewitt wrote:
I guess I wasn't too clear. I wanted to use one switch each for two
ladder line lead ins. Since no one I can find makes arrestors for
ladder line I am building my own from spark plugs threaded into a big
copper plate which is grounded with copper strap to 5 ground rods in a
fairly small circle outside the shack window. It's about 70 ft to the
200 amp service box from the bedroom I am using for my shack.
I just won a bid on ech bay for a double throw make before break knife
switch which I'll be using also. I'm going to buy one of those MFJ
window lead through plates with multiple ladder line connectors or
maybe make my own version.
I am wondering, instead of using just two spark plugs, if it might be
more effective to use 3 pairs in line with the first pair having
really wide gaps, the second having a medium gap, and the third having
a small gap around .035"? I am going to enclose them to keep them dry
and they will be grounded to the same rods as everything else.
I'll also have a Drake R-8 receiver in my bedroom hooked to an
Evesdropper trap dipole with a Zap Trap arrestor on the co-ax. It's
too far to run a ground to the other end of the house so I plan to
ground it outside of my window. I know that's not the best way but I
don't want to run an 80 foot ground cable to the shack ground.
Thanks for all the good advice. 73 Gary N9ZSV




On Sat, 11 Oct 2008 22:12:20 -0500, Gary Pewitt
wrote:

Here's a simple question. I want to connect my transceiver to several
antennas using 450 ohm ladder line and a balanced tuner. I found a
couple of small double pole double throw knife switches for the ladder
line. There are only two ways to hook these up. I can hook the tuner
output to the center with the ground on the bottom and the antenna on
the top connectors. This will allow me to connect the transceiver to
the antenna or to ground. The second way is to connect the
transceiver to the top contacts, the antenna to the center, and ground
to the bottom contacts. This will let me connect the antenna to the
radio or to ground. Is it better to ground the radio and let the
antenna float? Or to ground the antenna and let the radio float?
Of course if I leave the switch handle sticking straight up nothing is
connected to anything.
I am inclined to think grounding the antenna is better but I have been
wrong before.

Thanks and 73 Gary N9ZSV

I'd just use 2 coaxial gas tube suppressors, keeping the parallel
spacing the same as your ladder line. The coaxial suppressors just have
the center conductors going straight through, the little gas pellet
barely making contact inside.

Better to run fat Copperweld AROUND the house and clamp to several ground
rods then rather than having lightning going THROUGH the house from one
ground point to the other. Everything you do should make Primary, secondary
strikes and surges want to drain outside and away from the house/shack/site.

A large coil or high value resistor is a good thing for bleeding off static
charges on a line so that when you throw the switch, nothing goes through
you to ground. It is common for antennas that don't have some DC grounding
feature to build static charges if open. Your antenna tuner or the input
transformer of your receiver has to drain that. Polyphaser makes good
coaxial type surge protectors, but I'm not sure about Ladder line. The gap
type arrestor does have limitations because you have to keep the gap wide
enough to avoid problems with the transmitter. Multiple series gaps only
raises the firing voltage, but the breakdown voltage will be set by the
largest gap in the series. A gap at .035 will fire at about 2-10kv
depending on humidity. You only want it wide enough so that it won't arc
when keying the transmitter. If there is a direct hit they will probably
explode or at least blow the electrodes away.

I would seriously read up on the situation in addition to asking questions
on a newsgroup. Polyphaser may still have a free publication you can order
that explains things in depth.


"Gary Pewitt" wrote in message
...

I guess I wasn't too clear. I wanted to use one switch each for two
ladder line lead ins. Since no one I can find makes arrestors for
ladder line I am building my own from spark plugs threaded into a big
copper plate which is grounded with copper strap to 5 ground rods in a
fairly small circle outside the shack window. It's about 70 ft to the
200 amp service box from the bedroom I am using for my shack.
I just won a bid on ech bay for a double throw make before break knife
switch which I'll be using also. I'm going to buy one of those MFJ
window lead through plates with multiple ladder line connectors or
maybe make my own version.
I am wondering, instead of using just two spark plugs, if it might be
more effective to use 3 pairs in line with the first pair having
really wide gaps, the second having a medium gap, and the third having
a small gap around .035"? I am going to enclose them to keep them dry
and they will be grounded to the same rods as everything else.
I'll also have a Drake R-8 receiver in my bedroom hooked to an
Evesdropper trap dipole with a Zap Trap arrestor on the co-ax. It's
too far to run a ground to the other end of the house so I plan to
ground it outside of my window. I know that's not the best way but I
don't want to run an 80 foot ground cable to the shack ground.
Thanks for all the good advice. 73 Gary N9ZSV




On Sat, 11 Oct 2008 22:12:20 -0500, Gary Pewitt
wrote:

Here's a simple question. I want to connect my transceiver to several
antennas using 450 ohm ladder line and a balanced tuner. I found a
couple of small double pole double throw knife switches for the ladder
line. There are only two ways to hook these up. I can hook the tuner
output to the center with the ground on the bottom and the antenna on
the top connectors. This will allow me to connect the transceiver to
the antenna or to ground. The second way is to connect the
transceiver to the top contacts, the antenna to the center, and ground
to the bottom contacts. This will let me connect the antenna to the
radio or to ground. Is it better to ground the radio and let the
antenna float? Or to ground the antenna and let the radio float?
Of course if I leave the switch handle sticking straight up nothing is
connected to anything.
I am inclined to think grounding the antenna is better but I have been
wrong before.

Thanks and 73 Gary N9ZSV