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

Graham / KE9H ke9h.graham at gmail.com
Mon Jun 18 15:05:11 EDT 2018

If you want to protect your installation from lightening, then there is a
body of information that has been developed within the cellular industry
that allows a properly installed cellular base site to take a direct hit
and continue operating.

An example of what they do is documented in "Motorola R56 2005 manual.pdf"

Google that term to download the document.

It is likely more than most individuals are willing to take on, but you can
see the approach.

In addition to good grounding and common Voltage points, it also involves
making sure that there is not a Voltage differential across the equipment
that you want to protect, during the event.

There is an old folk saying that "Lightning never strikes twice."
Because it doesn't have to.

--- Graham


On Mon, Jun 18, 2018 at 1:39 PM Chris Smith <chris.smith at alum.mit.edu>

> 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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