grounding question
 

I have a discone antenna on my roof and the mast is grounded to the
earth with #8 solid wire with a ground rod.
I want to use lmr-400 wire for app 50 ft to the scanner. Is it
necessary to install the cable with an in-line arrestor ? I hate to
have to add more connectors if it isnt necessary...I always unplug the
scanner from my cable, rg-58, when Im not using it.....Any
thoughts.....Thanks Mike

grounding question
 

up to you really
but i'd be very carful about following the old wives tale about
disconnecting your coax during a storm.
this will then charge your coax with static that will discharge through your
equip when you reconnect it.
a shorted connector to a ground line would be much safer, if you wish to
disconnect

mike

"Mike" wrote in message
...
I have a discone antenna on my roof and the mast is grounded to the
earth with #8 solid wire with a ground rod.
I want to use lmr-400 wire for app 50 ft to the scanner. Is it
necessary to install the cable with an in-line arrestor ? I hate to
have to add more connectors if it isnt necessary...I always unplug the
scanner from my cable, rg-58, when Im not using it.....Any
thoughts.....Thanks Mike

grounding question
 

When I disconnect my antenna, I attach a 50-Ohm terminator to the free end
of the cable for the purpose of continuously discharging the
naturally-ocurring electrostatic charge.

- Doug


"mikeFNB" wrote in message
...
up to you really
but i'd be very carful about following the old wives tale about
disconnecting your coax during a storm.
this will then charge your coax with static that will discharge through
your equip when you reconnect it.
a shorted connector to a ground line would be much safer, if you wish to
disconnect

mike

"Mike" wrote in message
...
I have a discone antenna on my roof and the mast is grounded to the
earth with #8 solid wire with a ground rod.
I want to use lmr-400 wire for app 50 ft to the scanner. Is it
necessary to install the cable with an in-line arrestor ? I hate to
have to add more connectors if it isnt necessary...I always unplug the
scanner from my cable, rg-58, when Im not using it.....Any
thoughts.....Thanks Mike

grounding question
 

"DougSlug" wrote in message
...
When I disconnect my antenna, I attach a 50-Ohm terminator to the free end
of the cable for the purpose of continuously discharging the
naturally-ocurring electrostatic charge.

- Doug

Why not just leave a 10K or so resistor connected full time to the antenna?

Dale W4OP

grounding question
 

"Dale Parfitt" wrote in message
news:_2oyg.16225$6G3.10077@trnddc05...

"DougSlug" wrote in message
...
When I disconnect my antenna, I attach a 50-Ohm terminator to the free
end of the cable for the purpose of continuously discharging the
naturally-ocurring electrostatic charge.

- Doug

Why not just leave a 10K or so resistor connected full time to the
antenna?

Dale W4OP

What would be the reason for this? The receiver already has an impedance to
ground (2.2K in my AR8600 MkII), so it wouldn't be needed when connected,
and when disconnected, an inexpensive 50-Ohm terminator with the proper
connector is super easy to connect. Connecting an external resistor as you
suggest would require custom wiring (easy, yes, but why do it if not
necessary?).
- Doug

grounding question
 

Install a connection inline with coaxial cable that connects to ground. RS
may carry device. Has male/female ends with attaching point for ground
lead.

grounding question
 

"DougSlug" wrote in message
...

"Dale Parfitt" wrote in message
news:_2oyg.16225$6G3.10077@trnddc05...

"DougSlug" wrote in message
...
When I disconnect my antenna, I attach a 50-Ohm terminator to the free
end of the cable for the purpose of continuously discharging the
naturally-ocurring electrostatic charge.

- Doug

Why not just leave a 10K or so resistor connected full time to the
antenna?

Dale W4OP

What would be the reason for this? The receiver already has an impedance
to ground (2.2K in my AR8600 MkII), so it wouldn't be needed when
connected, and when disconnected, an inexpensive 50-Ohm terminator with
the proper connector is super easy to connect. Connecting an external
resistor as you suggest would require custom wiring (easy, yes, but why do
it if not necessary?).
- Doug
Is a 50 Ohm termination a special value for static discharge? Is it better
than a short or a 10K resistor? The permanently connected 10K would make it
unnecessary for you to screw on your 50 Ohm termination.

Dale W4OP

grounding question
 

Is a 50 Ohm termination a special value for static discharge? Is it better
than a short or a 10K resistor? The permanently connected 10K would make
it unnecessary for you to screw on your 50 Ohm termination.

Dale W4OP

I would think that the lower the impedance, the better, since a dead short
on the antenna would be the ideal situation when disconnected. The reason
it's 50 Ohms is because that's a readily available terminator. I'm using
BNC connectors, so the effort is minimal. The down side of leaving it
connected all the time is that, without a lightning arrestor, a strike would
probably damage the receiver, so I'm going to disconnect it in any case. I
don't think the 10K would protect against that.

- Doug

grounding question
 

On Sun, 30 Jul 2006 07:51:41 -0400, "DougSlug"
wrote:

I would think that the lower the impedance, the better, since a dead short
on the antenna would be the ideal situation when disconnected. The reason
it's 50 Ohms is because that's a readily available terminator. I'm using
BNC connectors, so the effort is minimal. The down side of leaving it
connected all the time is that, without a lightning arrestor, a strike would
probably damage the receiver, so I'm going to disconnect it in any case. I
don't think the 10K would protect against that.

Nothing, not even a dead short with #4 wire to ground, will protect
against a direct lightning strike - you're talking millions of amps.
And a 10k will protect against static buildup.

A 50 ohm termination is used to terminate unused outputs on a
splitter, because the only way the splitter will work properly is to
have a 50 ohm termination on each output - either cable to a receiver
or a non-inductive resistor.

grounding question
 

"Al Klein" wrote in message
...
On Sun, 30 Jul 2006 07:51:41 -0400, "DougSlug"
wrote:

I would think that the lower the impedance, the better, since a dead short
on the antenna would be the ideal situation when disconnected. The reason
it's 50 Ohms is because that's a readily available terminator. I'm using
BNC connectors, so the effort is minimal. The down side of leaving it
connected all the time is that, without a lightning arrestor, a strike
would
probably damage the receiver, so I'm going to disconnect it in any case.
I
don't think the 10K would protect against that.

Nothing, not even a dead short with #4 wire to ground, will protect
against a direct lightning strike - you're talking millions of amps.
And a 10k will protect against static buildup.

A 50 ohm termination is used to terminate unused outputs on a
splitter, because the only way the splitter will work properly is to
have a 50 ohm termination on each output - either cable to a receiver
or a non-inductive resistor.

All true, but my point is that the receiver already has a 2.2K resistor to
ground at the antenna input, so adding a 10K in parallel is completely
unnecessary. And using a 50 Ohm terminator on a disconnected antenna
downlead is no worse than using a 10K resistor. In either case, no
additonal wiring is needed, and the protection from static build-up is
there, which was the topic of the OP's question, I believe.

It still isn't clear why I should go to the trouble of wiring up a 10K
resistor on the antenna, and why using a 50-Ohm terminator on a disconnected
downlead isn't just as good (possibly better).

We do agree that, without a lightning arrestor, it's better to disconnect
the downlead during a nearby thunderstorm than to leave it connected with
just a 10K resistor, don't we? The method for draining static build-up may
vary, but both methods are valid.

- Doug

grounding question
 

On Wed, 2 Aug 2006 19:25:32 -0400, "DougSlug"
wrote:

We do agree that, without a lightning arrestor, it's better to disconnect
the downlead during a nearby thunderstorm than to leave it connected with
just a 10K resistor, don't we?

Well ...

If it's just hanging there and a few tens of thousands of volts come
down the cable, you may lose a few things - radios, furniture, the
house ...

I disconnect my antennas during thunderstorms and connect them to a
grounded block mounted directly on a good ground rod (right outside
the shack window). I've seen what a direct strike can do more than
once. It's not something you can protect against, but I'd rather lose
my antennas and cables than my house.