Lightning Protection Questions Fosr New Recv'r. ?

[BOBRR]

Hello,

Took the plunge, and purchased a WinRadio Excalibur SDR receiver.
I would like to protect it as best I can.

I do receiving only (<30 MHz), and have an end-fed antenna from PAR outside.
We get a fair amount of lightning in the area, but have never had any direct hits.

I have the typical ICE lighning arrester at the junction (outside) where the antenna joins the coax leading to my radio in a room upstairs.
The arrester is connected to a ground rod that I banged into the soil.

What concerns me most I think is the voltage being induced, possibly, by nearby strikes.
If anything actually hits the arrester, I doubt that it, or anything, would survive.
Probably more of a "feel-good" kinda thing than anything.

So, let me ask please.

a. Can "nearby" strikes, say 1/8 or 1/4 mile away actually induce meaningful voltages in the antenna (about 10 feet above the ground, running horizontally) ? How large ?

b. I try, but I am not always home, or remember always to do so frankly, to disconnect the antenna when done using the radio. "Old-Age" problem, apparently.

What kind of "protector" can I put right at the radio to try to protect against any
voltage surges (not direct hits) ?

c. What about voltage surges coming in via the AC line ?

d. What about static (buildup) charge ?
Are most modern radio front-ends, like hopefully on the Excalibur, reasonably protected against static buildup and "low" voltages ?

e. I've read about the Polyphaser line of gadgets. Is one of these what I possibly want for directly at the radio input in the house ? They sure are pricey.

It, or anything used here, would only have as a ground a wire strapped to a forced hot water heating pipe (which is also electrically connected to the house water supply)

I've also read about using neons back to back, and 10 meg ohn resistors, etc.
Seems to be a lost of cons to this approach, as well as possible benefits. Thoughts on ?

Any thoughts on all of this would be most appreciated.

Thanks,
Bob

 

[davidgcet]

you need to connect that ground rod to your main electrical ground system so that both ground are are equal potential. otherwise a strike can jump from one system to the other and destroy a lot of stuff.

and yes nearby strikes will cause damage, though not as much as a direct hit.

forget 10 meg resistors and neons, a hit will blow them apart and continue to jump right across them. they may work fine for a small nearby strike, but won't stop a strong close one. polyphaser is not as expensive as you may think, 70-100.00 for a protector that could save a radio worth several times that. they also make units for the AC side and i recommend using one.


just keep in mind that you should do as much as you can reasonably do to protect against lightning, other than the above suggestions you certainly don't have to bring it up to the specs of a cell site though. the object is to bring everything as close to the same ground potential as possible so that the path to ground is as short as possible and does not require the strike to travel thru equipment but around it. there is little you can do to protect against a direct strike without spending major bucks.

 

[jim202]

Hello,


I have the typical ICE lighning arrester at the junction (outside) where the antenna joins the coax leading to my radio in a room upstairs.
The arrester is connected to a ground rod that I banged into the soil.

What concerns me most I think is the voltage being induced, possibly, by nearby strikes.
If anything actually hits the arrester, I doubt that it, or anything, would survive.
Probably more of a "feel-good" kinda thing than anything.

So, let me ask please.

a. Can "nearby" strikes, say 1/8 or 1/4 mile away actually induce meaningful voltages in the antenna (about 10 feet above the ground, running horizontally) ? How large ?

d. What about static (buildup) charge ?
Are most modern radio front-ends, like hopefully on the Excalibur, reasonably protected against static buildup and "low" voltages ?

e. I've read about the Polyphaser line of gadgets. Is one of these what I possibly want for directly at the radio input in the house ? They sure are pricey.

I've also read about using neons back to back, and 10 meg ohn resistors, etc.
Seems to be a lost of cons to this approach, as well as possible benefits. Thoughts on ?

Any thoughts on all of this would be most appreciated.

Thanks,
Bob

Let me give you an example of static buildup on an antenna system. When I was building cell sites
in the New Orleans area, I would have to be at some of the sites either at night or very early in the
morning. The weather in that region is very prone to thunder storms and the associated lightning.
One of the sites we have been at is a cluster of very tall TV (1100 feet) and AM radio towers. If
there is a storm even in the far distance, the insulating isolators on the tower guy wires will start
to crackle and gradually build up until you see a lightning bolt in the distance. They stop crackling
and sparkling at that point then it starts all over. So yes, you can have a static build up even though
the storm cloud may be 10 or more miles away.

The ground for your Poly Phaser grounding protectors needs to be of a good size wire, Generally
in the industry, you will find a number 2 or larger used for grounding. The ground RODS are inter
connected with at least a number 2 solid, tinned wire. Almost all of the connections are done via
an exothermic weld process. Again this cuts down on corrosion and provides the lowest resistance
possible. The ground rods are spaced at least twice their length for maximum benefit. It takes
multiple ground rods to obtain a low resistance ground system.

Hope this provides some info on your quest for grounding and surge protection.

 

[towerclimber37]

heheheh "exothermic weld process"
Jim, you're going to have to ease up on the fella. tell him cad weld or you'll pop his head.

Ground everything Bob. Cell sites use a "ground ring" of #2 tin that's cadwelded together, and it's put at a MINIMUM of 3 feet in the ground.

If static electricity is a problem, ground not only your tower, but run a ground to a copper or ground plate and use that to ground all your radio gear.

Jim knows what he's talking about, heed his advice.
Believe me, no one wants to avoid a lightning strike more than a company that has half a million dollars of equipment on a tower site. They call in guys like Jim to keep that from happening...then they call in guys like ME to make it happen.

 

[BOBRR]

From OP:

Hello,

Much thanks for all the good info.
Appreciate it.

Bob

 

[wyomingmedic]

glad you are asking and taking lightning protection so seriously. It is an extremely important fact that gets overlooked by many.

What needs to happen is a single point ground system be made. ALL wiring in your house (electric service, cable, phone, coax, ETC) goes through 1 ground point. It makes it so the voltage potential stays the same throughout the system.

Here is my grounding setup. A properly designed system should be able to take a direct lightning strike. I use Poly Phaser setups with gas discharge tubes. They are SUPPOSED to pop fast enough to protect even mosfet finals. They will also protect against errant static and nearby strikes.

My poly phasers are mounted to a 1/4 inch thick brass plate which is tied to a series of ground rods. All of the electrical wires going into the house are grounded through this plate.

I should say, I have a 60 foot tall tower with lots of aluminum in the air. I am on a tall hill here in the rocky mountains, so I stand a FAR greater chance of a direct strike compared to a low wire. So you may not need to go to the level I do.

WM