[TowerTalk] Total station grounding and ethernet (summary)

[Curtis, David B]

Dave,
   Interesting thought... It conforms with N6NZ's 1st law of device
electronics: "All electronic devices except for the fuse have at least two
regimes of operation, one where they act as a fuse, and one or more where
they serve some other function." (Popular examples in my line of work are
electrolytic capacitors and microprocessors :-)

   But... how can one be sure that the hub will: a) fuse with a lightening
hit, b) not pass the hit through, and c) not catch fire?  If all of these
are true, then I agree, let the hub roast.  I wouldn't want it to start a
fire, though.

73, Dave N6NZ

  Related aside: I recently had some event simultaneously take out both a
hub and an ethernet card. Never did figure out what.  Of course, the
ethernet card it took out was the one in my laptap that I was carrying
around the house trying to diagnose the first point of network failure...
that led me on a merry chase.

-----Original Message-----
From: Dave [mailto:depagnier@uswest.net]
Sent: Sunday, June 04, 2000 5:25 PM
To: pete.soper@sun.com; towertalk@contesting.com
Subject: Re: [TowerTalk] Total station grounding and ethernet (summary)



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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