"Spark gap" in a grounding block ??

[bhelms]

If this is in the wrong forum, please feel free to move it...

What's in the common F-connector grounding block? Is it simply a solid bonding connection for the shield or is there any protection provided for the inner conductor as well?

Seems to me some years ago when I was selling CB equipment, there was a spark-gap lightning protector for the RG-8 (or 58 as well) antenna cable that provided an actual spark gap in the device to protect the signal lead. It was adjustable with an external screw/locknut. (Too many folks thought that was an attachment point for the ground wire and torqued it down, shorting-out the device.)

Did I dream that or did it actually exist? Is there something comparable for the 75-ohm systems?

TIA and BRgds...

 

[Van]

Just the shielding on the coax, otherwise its nothing more than two barrel connections jammed into a ground lug.

 

[Pepper]

Must be, there's no way LNB voltage could make it thru a spark gap.

 

[bhawley]

Spark gap:
http://www.mylife4christ.com/ProductInfo.aspx?id=1611131

Sat. protection (solid state):
http://www.panamax.com/Literature/PDF/SAT_BROCHURE.pdf

 

[bhelms]

bhawley - Tks for the links - that first one is almost exactly what I remembered!

Pepper - actually the spark gap has virtually no impact on the signals themselves including the power. It's just a pair of points spaced such that any pulse in the "hot" line (center conductor) greater than a determined threshold voltage (500 volts in the case of the linked unit) will jump that gap in what then becomes a very low-impedance path to ground (the arc) and thus avoid traveling the length of the coax, which has a higher impedance, to damage the equipment at the far end. Unfortunately the linked unit is a low-frequency PL-259/SO-239 combination that is not suitable for TV/sat. applications. I was hoping there was something suitable for ~2.2GHz, or at least the UHF band.

In all probablility a spark gap won't do any good in a sat. connection - the components in the nearby LNB would be wiped out long before the pulse could build to a level high enough to jump the gap. But one would still be useful in an OTA downlead in a system that did not have any antenna or mast-mounted amp.

And that's exactly what I had in mind. I'm refurbishing my OTA system in an area that gets a lot of lightning activity...

 

[bnaivar]

The only problem with spark gap protectors is that by the time they fire, 499 volts have already passed through your equipment.

 

[bhelms]

That's not necessarily true! The spark gap should be located at the antenna and properly connected with a low impedance path to ground. A pulse from a lightning bolt or similar is almost instantaneous. Due to inherent propagation delay in the signal transmission path and its inductance, the voltage spike along that path does not also build as quickly or to the same level. The spark gap can "fire" quickly and the rest of the system won't see that same full spike. Your statement would be true if the voltage builds slowly, and in that case the spark gap would be completely ineffective...

 

[Van]

Panamax makes the best surge protectors that I have ever seen, never seen a bad one nor have I seen one fail.

 

[bhelms]

Panamax makes the best surge protectors that I have ever seen, never seen a bad one nor have I seen one fail.

I have bookmarked that link for when I need to replace my current ones. I usually do that about annually since I know the MOVs in these units weaken over multiple hits such that they don't give their best protection after a while.

Tks guys...

 

[Grampaw]

Lightning Arrestors work !

I had a transmit antenna at the top of a 300 foot tower wiped out by a lightning strike. Also blew the arrestor. Transmitter was OK. Much better for the bottom line to replace a $600 antenna than a $30k transmitter.
As long as you use arrestors with the the correct frequency rating you should be fine.

Walt

 

[Van]

Panamax garauntee's for the life time of the surge if I remember correctly, I used to sell 1 - 6 a day when dish carried them on the vans and we got commisions on upsells.

8 outlettes with one side that has an on off switch, an indicator light that it is getting power and another light telling you wether or not it is connected to a grounded outlette, found quite a few homes with faulty grounds that way.

 

[SimpleSimon]

As long as you use arrestors with the the correct frequency rating you should be fine.

Yup!

Note that gas discharge arrestors are nice, but will NOT pass power.

 

[bhelms]

Lightning Arrestors work !

I had a transmit antenna at the top of a 300 foot tower wiped out by a lightning strike. Also blew the arrestor. Transmitter was OK. Much better for the bottom line to replace a $600 antenna than a $30k transmitter.
As long as you use arrestors with the the correct frequency rating you should be fine.

Walt

I agree re: the frequency rating, but we're not finding anything rated above about 300MHz.

The in-house surge protectors are a great alternative especially with the "guarantee". Actually the mfgrs know full well that their products won't protect against a near or full strike. They're rolling the dice that the amount of pay-outs for replacement equipment is less than the added sales due to the guarantee. I have all my valuable electronic equipment protected by these kinds of devices - I even tape copies of the warranties, receipts, etc. right to the units so I can easily document a legitimate claim if I ever have to.

But I'd still rather stop that surge close to its origin, like Grampaw reported, than take my chances with the "arrestors" at the equipment...!

 

[Van]

panamax makes a whole house surge supressor that bolts in right next to the fuse box, only seen one but it was nice and knowing the company and its product Im sure that it does its job well.

 

[bhelms]

I have "incoming" suppressors on both my electical panel and my phone line. No comments +/- about them - they're just "there". I once lost a phone in a near strike and we used to get momentary rings on multiple phones when there was atmospheric electical activity in the area, which prompted me to make these additions. Since then, no additional noticeable surges in the phone system, not sure about the power (we do have some flaky things happening out here occasionally in the boonies). But I can't really be sure they're actually "working", whatever that means...

Tks all for the feedback...

 

[SimpleSimon]

Call me paranoid, but I use multiple levels of surge protector.

One to the wall, and then either another one, or a UPS depending on application.