[TowerTalk] Total station grounding and ethernet (summary)

[Dave]

Pete, be careful not to spend more money attempting to protect something than what
that something is worth. An ethernet hub is a relatively inexpensive item to replace
in the unlikely event that it would ever get damaged.

--Dave
K0QE

Pete Soper wrote:

> For running ethernet into my station building I wondered if I could make a
> simple surge supressor with MOVs to clamp each of the four twisted pair
> conductors of a CAT5 cable run to the single point ground at the cable
> entrance into my station.
>
> This wouldn't work as MOVs have enough capacitance to foul up ethernet
> according to multiple folks who wrote to me. (If I can find the special place
> where I hid my LC meter I'll report some measurements)
>
> The perfect solution is to run fiber into the station instead of copper.
> Transceivers that translate between fiberoptic ethernet and copper are
> available and sometimes inexpensive (a quick check of ebay found an
> FL to AUI transceiver whose high bid was $9.50).
>
> For twisted pair (i.e. 10baseT) ethernet APC makes the model PNET1 suppressor.
> It clamps at 8 volts and protects all eight conductors (and uses RJ45
> connectors). Polyphasor also provides some products for twisted pair but none
> seemed to be a match for my application.
>
> As I've already invested in the copper bits and pieces I'll be using one PNET1
> on each end of the CAT5 between my house and the station. The second PNET1 will
> be go between the house end of the cable and my firewall box, saving me a hub
> (which I was going to put in between so the hub would take the zaps and
> hopefully spare the firewall).
>
> The APC info on the PNET1 and the vendor where I ordered a pair for $39.94
> shipped are here:
>
>         http://www.apcc.com/products/protectnet/pnet1.cfm
>
>         http://www.onvia.com/streetprices/home/index.cfm
>
> (There were no comments about fusing or specifics about how much of an impedance
> bump 10baseT can tolerate.)
>
> Thanks for the help!
>
> Pete
> KS4XG
>
> PS This didn't go through on Friday because of the lack of a reply-to field
> matching the one I used for subscription. Gotta remember that majordomo looks
> at "reply-to" instead of "from" so you can post from multiple places.
>
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