Hi
And grounding coaxials is good for other porpoise than protecting equipment,
for example to reduce noise? Or doesn't help to reduce noise at the station?
Thanks
Jorge
CX6VM/CW5W
Enviado desde mi iPhone
> El 28/12/2014, a las 09:51, "David Robbins" <k1ttt@arrl.net> escribió:
>
> The PRIMARY place for arresters is at the equipment you want to protect.
> Other places like at the base of the tower are only protecting the coax or
> maybe a remote switch. To protect the radios put them at the entrance
> panel, anywhere else is a waste of money.
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt@arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim
> Thomson
> Sent: Sunday, December 28, 2014 04:19
> To: towertalk@contesting.com
> Subject: [TowerTalk] Arrestor placement
>
> Date: Sat, 27 Dec 2014 18:48:41 +0000 (UTC)
> From: David Gallatin via TowerTalk <towertalk@contesting.com>
> To: "TowerTalk@contesting.com" <TowerTalk@contesting.com>
> Subject: [TowerTalk] Arrestor placement
>
>
> Hello all,Somehow I have gotten the idea that one's lightning arrestors are
> best placed at the bottom of the tower. This seems logical to me. Then I came
> across another piece that said, no, arrestors are to be placed at the shack
> entrance panel. Which is it? Or does it matter???73, David, AA9G
>
> ex W5DCG and KC9EEV
>
> ## Install one at the base of the tower AND also where the coax enters the
> home. In my case, the two arrestors are 65 feet apart.
> The one at the base of the tower is aprx 4 feet above ground. Base of
> tower is earth grounded via 3 x 8 foot deep copper clad
> ground rods..all cadwelded. 2 ga bare cu wire to each leg of the tower.
> Another 65 foot of bare 2 ga cu wire, C clamped to
> basement entrance + SPG...where a 4th ground rod is installed...and also
> cadwelded. The HOFFI brand lightning arrestor at the
> base of the tower serves other functions. It’s the interface between the
> rigid coax from the shack to the base of the tower.
> Flexible coax from tower lightning arrestor going up the side of the HDX-689
> crank up tower. Lightning arrestor in mounted to the
> spg is the 2nd hoffi brand arrestor. Remote coax switch box is mounted to
> the mast. All braids from each yagi coax is bonded to the
> mast via the remote switch box. The lightning arrestor at the base of the
> tower bonds the coax braid to the base of the tower... via the
> casing of the lightning arrestor.
>
> ## Like K1TTT points out, you need a 2nd arrestor where the coax enters
> the home. Now if the tower base is close to where the
> coax enters the home, then you could get away with only the one arrestor.
> If hairpin or beta matches are used on the yagis, the center conductor
> will be bonded to the braid of the coax anyway..right at the feedpoint..via
> the hairpin or beta match. In the case of the beta match, both the center
> conductor and braid are bonded to the boom. Either way, the center
> conductor is bonded to the braid..which is then bonded to the top of the
> tower.
>
> ## If it gets past all of that, the arrestor at the base of the tower
> should do the trick. If it gets past that, then it has to get past the
> arrestor at the SPG.
> If you have a OWA yagi, the center conductor is not bonded to anything...
> and the arrestor is def required. You could always install a 15-50 uh coil
> across the feedpoint of the OWA... which may not be effective for lightning
> hitting the center conductor side of the DE. A 3rd arrestor at the top of
> the
> tower would also work with any OWA yagi.
>
> ## A 35 uh coil or 12 ga magnet wire wound on a torroid like ICE uses....
> at the spg will also dc ground the center conductor. ICE uses the back emf
> across the coil to fire the gas discharge tube that is in parallel with it.
>
>
> Jim VE7RF
>
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