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Re: [TowerTalk] Gas Tube protection for remote antenna switches;

Subject: Re: [TowerTalk] Gas Tube protection for remote antenna switches;
From: "Roger (K8RI)" <>
Date: Mon, 26 Jul 2010 21:57:39 -0400
List-post: <">>

On 7/26/2010 8:46 AM, Jim Thomson wrote:
> Date: Mon, 26 Jul 2010 06:21:30 -0400
> From: Pete Smith<>
> Subject: [TowerTalk] Gas Tube protection for remote antenna switches;
> shorting coax cables when disconnected
> Yesterday we had a severe thunderstorm episode, with significant
> cloud-to-ground lightning nearby.  All my coax and control lines were
> disconnected, but when one particularly close strike occurred, an arc
> jumped across the open SO-239 on my entry panel.  No damage in the
> shack, fortunately, but it set me wondering.
> 1.  Does it make sense to put a shorting plug at the shack end of a coax
> cable?  With my Ameritron RCS-10 relay box, putting a shorted PL-259 in
> position 1 on the relay box has the same effect when the control cable
> is disconnected, except at the tower end.  A better idea?
> ##  putting a shorted pl-259  in pos #1  just used up pos #1.
and still leaves the other connections/positions open. Not good for 
lightning protection.
> Why not use a torroid.. like 45 uh... using 10-12 ga magnet wire. Then,
> the center conductor is always at DC grnd.  [ on the cable heading towards
> the station.. ie:  input side]
> ## does the ameritron  grnd, or float the un-used ports ??
"Out of the box" they float, but it's a very simple job to have the 
unused connections grounded. Power down and all are grounded. It's a 
simple solder bridge between two foils, or for the solder challenged, a 
short piece of #12,  14, or 16 can be soldered in place.
>   My AS
> box grnds all the unused ant ports.    DPDT relays  are used, one per
> port.  Common  goes to ant port,  NC  goes to grnd buss... and NO
> goes to kw input buss.     If lightning present, all Unused ports are grnded.
> If power to control box is shut off, or rotary switch thrown to pos 7-12.. 
> then
> all  ports  1-6  are grnded.
> ## You could also install an ICE arrestor, or similar, at shack end... then
> the center conductor is always DC it has a gas discharge tube
> in parallel with the  12 ga , 35 uh torroid they use.   It's also dc 
> blocked... and
>   the station side of the block caps has series resistors  going to grnd.   
> You could
> also install a 2nd torroid on the station side of any dc block cap.
> ##  I'd also grnd all the braids if all coax cables   at the top of the 
> tower....
> then run the coax down the inside of the tower .. and also grnd the braids  
> at base of
> tower.
That's what I've done here.
>     Then install the ICE  arrestor or eq in the station.
Then the arrestor is mounted on the grounded bulkhead where the cables 
enter the shop and house.
> ##  IF the yagi uses  either a hair pin  [floating]    or a beta match [ 
> grnded hair pin]  then the
> center conductor is grnded anyway.   If no hair pin is used... like on an OWA 
>  design.... I see no reason
> why a  35-70uh   choke couldn't still  be used  directly across the DE.   If 
> a remote switch box is used, at least you have
> all the braids grnded at top of tower already.
> 2.  Ameritron makes a "lightning-protected" version of the RCS-10,
> called the RCS-10L.  From the parts list (no schematic) it appears that
> the only added component is a gas tube, rated at 1500V, 10 KA.  I
> presume this is across the output of the relay box coming to the shack.
> Again, good idea?
I have multiple RCS-8s on the tower one for 75 and one for 40. These are 
fed from a "six-pack" which allows for two stations to use the system.
> ##  sure, that will work.   But can u take the box apart to change out the
> gas discharge tube, with no hassle ?   On the German Hoffi brand lightning
> arrestor's,   it takes no time at all to change out the gas discharge tube.  
> Same
> deal with the Suhner + also the Spinner brand of lightning arrestor's.
Seems like I read the tube is easy to change in the ice units, but 
that's relying on a rather shaky memory.
> ## did Ameritron install the gas tube on the side of the remote box... for 
> easy access ?
> 1500 V    means the gas tube is good for  20 kw  with flat swr... and 10 kw  
> with  a 3:1 swr.
What about 6 or 7:1?


Roger (K8RI)
> Later... Jim  VE7RF

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