Surge from Surge Suppressor

• Feb 8, 2005

• #2

bearing01

Electrical

Oct 4, 2004

14

US

I don't quite understand your question. Are you referring to a lightning arrestor - that you mount in series with your coax as it enters the building from the antenna? Lightning arrestors ground the instantaneous voltages that may occur if lightning hits the antennal

 

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• Feb 14, 2005

• #3

SolderingGunslinger

Electrical

Feb 11, 2005

126

US

If you are referring to a lightning arrestor in an antenna circuit, the shortest path to a good RF ground is needed. Lightning is a series of really high amplitude square waves and all of the harmonics thereof. in Lightning transients, there is Appreciable power containd in transients extending into the gigahertz.

A 4-0 conductor looks reactive (Usually Inductive) at frequencies above 400 MHz. This is why wide copper strip is used in broadcast facilities. Replace or augment the 4-0 with a 4" wide copper strip and make the run to the ground as short as possible.

Check out Harger for grounding (

http://www.harger.com)

for lightning protection equipment and supplies.

Good Luck

I rfemain,

The Old Soldering Gunslinger

 

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• Feb 14, 2005

• #4

IRstuff

Aerospace

Jun 3, 2002

44,892

US

OSG,

You can modify your profile to include your signature

TTFN

 

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• Feb 15, 2005

• #5

VEBill

Military

Apr 25, 2002

7,090

CA

"...in lightning transients, there is appreciable power... ...extending into the gigahertz."

You sure about that?

Although noise from lightning can interfere with LF/MF/HF over huge distances, once one reaches VHF and above, lightning is rarely (if ever) mentioned as a source of interference.

 

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• Feb 15, 2005

• #6

SolderingGunslinger

Electrical

Feb 11, 2005

126

US

I agree, lightning isn't a source of interference at a distance from the strike in the upper VHF and UHF range, however we are talking about protection from induced currents in a nearby strike. I have seen the front end of KU band LNBs cleaned out by induced RF from a nearby strike.

One thing I forgot to mention is that little can mitigate damage from a direct strike. I was a bit tired when I posted last night. I had to drive a tower crew to the site just before sign-off, and back after the Nitrogen leak in the 6" line was identified. The Thiokol Spryte wasn't all thet Spry last night, and I don't sleep all that well in the transmitter building.

--SGS

 

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• Feb 15, 2005

• #7

VEBill

Military

Apr 25, 2002

7,090

CA

Just because the device that was damaged is a Ku-band device (even the 'front end'), it doesn't follow that the energy that damaged it had to be in the Ku-band.

If lightning contained significant energy at Ku-band, then these same satellite TV systems would drop sync for several seconds with each lightning bolt - and they don't.

 

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