[TowerTalk] Total station grounding and ethernet (summary)

[Pete Soper]

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.


--
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com