[time-nuts] GPS Antenna Grounding/Lightning protection.

Scott McGrath scmcgrath at gmail.com
Mon Jun 18 22:21:13 EDT 2018


You might want to look at your grounding system.   Your tower ground is probably not connected to your building ground.   So when a nearby strike occurred there was a potential difference between your grounds and a current flowed as a result.

My house/shack/tower is within a ‘halo’ ground with rods every 20’ or so this means in the event of a nearby strike all grounds are at SAME potential.    And yes during intense storms i do see ‘St Elmo’s Fire’ up on the tower which tells me system is working as intended by preventing potential buildup.

Content by Scott
Typos by Siri

On Jun 18, 2018, at 2:38 PM, Chris Smith <chris.smith at alum.mit.edu> wrote:

I have purchased and deployed Huber+Suhner lightning protectors
<https://www.hubersuhner.com/en/products/radio-frequency/lightning-emp-protectors/gas-discharge-tube-gdt-protectors>
in the past but have thankfully never suffered an actual strike, so I can't
say how well they work under duress.

I've heard it said that basically nothing can protect you from a direct
hit, but again, I haven't had the opportunity to test that theory that you
so recently suffered.

On Mon, Jun 18, 2018 at 2:29 PM, Dan Kemppainen <dan at irtelemetrics.com>
wrote:

> Hi,
> 
> I have (or had, I guess) a GPS antenna on a tower that took a lightning
> hit yesterday.
> 
> You can tell it's going to be a bad day when you walk into your shop, and
> smell burnt electronics. Still have to troubleshoot exactly what got hit,
> but the GPSDO was flashing no GPS signal, the 5V supply for the antenna to
> the GPS splitter was dead, the data logging computer had rebooted and the
> data logging computer monitor was dead. Other network hardware was dead
> also.
> 
> This is a bit surprising since the tower itself is grounded with 4 ground
> rods and bonded to a 150 foot deep well casing near by. The antenna is on
> the end of 250 ft run of RG6. The GPS antenna cable shield has a grounding
> block bonded to two ground rods driven down below the basement foundation
> where it enters the house. I'm guessing the surge ran the coax into the
> splitter, then through everything connected to it, despite the grounding
> block.
> 
> So, I'm wondering if there are better surge protectors for lightning
> protection? Maybe something that actually protect the center conductor
> also? Hopefully something that will pass GPS signal reasonably and let DC
> power through. If so, can you recommend some starting points? Other
> suggestions also welcome.
> 
> 
> Also, If you are considering upgrading your own lightning protection,
> hopefully this will be some inspiration to get started. As I said earlier,
> it's a bad day when you smell burnt electronics in the shop.
> 
> Thanks,
> Dan
> 
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