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Author Topic: Disconnecting stations when not in use?  (Read 17293 times)
W4KPZ
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« Reply #15 on: March 31, 2011, 04:08:40 PM »

A good ground system and a good lightning insurance replacement policy.
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KB9CRY
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« Reply #16 on: March 31, 2011, 04:12:19 PM »

After asking extensive questions on this subject on this and other forums I gave up looking for an answer!  Everyone has an opinion, and not an answer; including me!  I guess this is because Lightning is an untamed beast, you never know how it  will behave, even with the best protected systems such as Big AM Radio Stations, Aircraft etc. you hear stories of it causing problems from time to time.

I gathered two things after weeks of research.

1) Use as many multi connected 10ft ground rods as possible going around the perimeter of your house, three or more is best and connect that chain of grounds to your panel box ground. Your tower or Mast should of course also be grounded to the Rod nearest to it, and if it's a tower you need 4 Rods or more in the corners of the tower. Then connect every piece of gear to that ground system, including the Coax and rotator surge protectors.   You should have at least one coax protector near the Antenna and at least one more just before it enters the house. If your soil conductivity is too high all of this may be a mute point so it's best to have that tested.

2) If you get a direct strike you will find that all the steps in number one might or might not save your equipment.  So you have only bought yourself real protection against an indirect strike.


You are wrong.

The system you propose in #1 is not a properly designed system.  You need to do more homework from reputable sources.
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K9KJM
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« Reply #17 on: March 31, 2011, 09:39:56 PM »

I agree with CRY.

Think it over.   Cellphone towers, commercial two way radio, Police, Fire, Ambulance, etc.
When operating with a properly designed system operate right through storms including taking DIRECT strikes to the tower with no damage to equipment.

Space your ground rods about TWICE the distance apart as the depth, And bond all together with a nice low inductance conductor. Flat copper strap, Heavy wire (#6 is MINIMUM) Or you can use hollow copper tube sold in rolls IF you are careful to not kink it.  No sharp bends anywhere in the system.

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KD8MJR
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« Reply #18 on: March 31, 2011, 10:51:01 PM »

You are wrong.

The system you propose in #1 is not a properly designed system.  You need to do more homework from reputable sources.

I know the rods need to be spaced twice the distance of there length and I also know about using nice flat wire and also a ground copper plate to bolt down all arresters.
I was just trying to keep the summary a bit short.

The first thing I heard the experts say is that a TV station will spend 10's of thousands of dollars on grounding and still not have a 100% bullet proof system.You and the OP might find this interesting, I looked at it during my research.

http://www.youtube.com/watch?v=rV4iUBM4n0Y

Even this is no Guarantee, and if you can afford a deep ground, hats off to you.
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K9KJM
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« Reply #19 on: April 01, 2011, 12:18:14 AM »

I have seen (And worked on) LOTS of commercial tower systems.  The "station" shown on the Utube video is clearly a "low dollar" installation, Trying to get by with as little as possible, Using apparently a very small parcel of real estate right in a city situation where they could not get a decent ground system installed, Short of the deep ground. SO what is the point?   IF you cannot install a correct rod system, Or radials, Etc. Then the "Deep Rod" (Actually a deep drilled well casing) is close to your last resort. (I oversaw a tower installation for the local Sheriff Department a few years ago that had the "deep ground" installed IN ADDITION to a convential rod system because of the local soil conditions.  (Mostly uncompacted "fill" in the tower area.) 
The 100 foot plus  deep ground "rod" IS expensive.   And in most normal cases not needed.

(I connected my first ham radio tower by my house  to my own private well case back in the 1970's just to add to it's ground potential.
In spite of dire warnings of damage to my well pump, That tower Has taken many direct lightning hits with NO damage to the well pump OR any ham equipment.)

Yes, When you hire others to do the work, The bill and price can add up in a hurry! 

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KD8MJR
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« Reply #20 on: April 01, 2011, 03:00:32 PM »

Look as I said at the start, I don't have the Answers and I don't believe you do either.
Lightning is a very strange beast that comes in many many forms.  I have seen the aftermath of a direct strike by a major  bolt and if that had hit a tower it probably would have melted the ground points into wet solder! Because it blasted the hell out of a steel pipe, melting it!

What I do know, is that all the literature that I have read almost always states that what they advocate cannot guarantee your system will survive a Direct strike.  On another note, aircraft get struck all the time, yet you can read about stories where a strike caused on board problems while thousand of other planes of that exact model had none when struck.  If lightning is so scientifically well known, why is it NASA freaks out if the shuttle gets struck?
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KD5FHW
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« Reply #21 on: May 30, 2011, 06:29:35 AM »

I simply disconnect the coax at the back of the radio. My chimney-mounted antenna mast is bonded to the mains ground with #6 solid copper, but I have yet to install a "shack" ground (I plan to do so) and coax lightning arrestors.
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K1CJS
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« Reply #22 on: May 30, 2011, 06:57:44 AM »

Depending on the site, commercial tower installers will sometimes have a well driller rig come in to drive a shaft into the ground for the 'grounding' of the tower and it ancillary equipment.  The idea, I guess, is to get the ground shaft into the wetter soil underneath the tower--to increase the area of conductivity of the grounding system.  A well drilling company I worked for for a short time often was called on for this purpose.

The only thing is that such a 'ground rod' is impractical for most of us, both from the cost factor and the fact that it is, in most cases, overkill for the purpose it would be put to.

Now, for the original question.  Get a coax switch.  It should have a ground position.  Use that position when the station isn't in use.
« Last Edit: May 30, 2011, 05:05:42 PM by K1CJS » Logged
W6RMK
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« Reply #23 on: May 31, 2011, 07:51:08 AM »


Space your ground rods about TWICE the distance apart as the depth, And bond all together with a nice low inductance conductor. Flat copper strap, Heavy wire (#6 is MINIMUM) Or you can use hollow copper tube sold in rolls IF you are careful to not kink it.  No sharp bends anywhere in the system.



There is no real advantange in using strap over wire, and wire is easier to install and manage. From a *lightning ground* standpoint, they ALL have significant inductance (which doesn't depend on the shape of the conductor very much): what you care about is whether everything is bonded to the same potential, and that it doesn't melt.  This requires a surprisingly small diameter wire (AWG 6 is what code calls for, for a reason)

The "no bends" isn't from inductance, it's more from making sure the wire/conductor doesn't fall apart from electromagnetic forces during the lightning pulse.  tighter bends aggravate the problem.

(calculate the inductance of a quarter turn coil... now compare that to the inductance of a straight piece of wire with the same length as the perimeter of the turn...  It's about the same)


Transmitter installations use copper strap to reduce RF resistance losses: watt hours heating up the ground conductors are dollars lost.  If you're running a vertical radiator, then you too may want to use strap, but don't do it for some sort of lightning protection reasons.
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WB4TJH
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« Reply #24 on: June 17, 2011, 06:37:58 PM »

I physically disconnect my antennas from the tuner, and ground them seperately. My radio is ALSO removed from ground, since lightning can come up the ground wire. I have been using this simple system for the past 41 years and have never had a piece of gear damaged from lightning or static discharge. If there is a really bad storm in the works, despite the presence of an anti surge device, I also unplug my power supply from the AC circuit. By removing my expensive gear from ALL electrical grounds/paths, I prevent any type of lightning from getting into it. Nothing is 100% foolproof, but like I said, in 41 years on the air, I have never had any damage to my radios, while several nearby ham friends have suffered massive lightning and static damages over the years. 
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KK0G
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« Reply #25 on: July 05, 2011, 06:31:23 PM »

Do you guys that unplug your shack before a storm also unplug your TV, DVD player, satellite receiver, telephone, computer, microwave oven, stereo system, dishwasher, central air conditioner and refrigerator?

There's a reason I pay for insurance.
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KB4MB
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Posts: 295




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« Reply #26 on: July 07, 2011, 05:47:30 AM »

Do you guys that unplug your shack before a storm also unplug your TV, DVD player, satellite receiver, telephone, computer, microwave oven, stereo system, dishwasher, central air conditioner and refrigerator?

There's a reason I pay for insurance.

I do for the dsl modem and the computer, yup.  Have had both fried at some point, and so I just made it very convenient to pull it when I need to.  I suppose I should for the main tv/stereo/satellite as well, but I guess I like to live on the edge Smiley

I'd rather keep my equipment and not deal with the hassle of filing a claim - but that's me.  I have had electric fences BLOWN up by lightning - I disconnect that as well and have had the same one now for many years now by doing that.

The way I look at it - if it is easy to do and cheap, why not.  All of the outside wires are grounded at the same point, so I am covered there - so disconnecting isn't a liability, so why not just do it.  I disconnect anytime I am not operating in the Spring/Summer/Fall (leave connected in winter), and lo and behold, no damage Smiley 

When I was a novice, I used to leave the dipole connected all the time with a poor water pipe ground, and guess what - front end damage...
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K1CJS
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« Reply #27 on: July 08, 2011, 05:15:23 AM »

All this thread is doing is giving reason after reason for a GOOD station grounding SYSTEM.  Not just one ground rod, but at least three if not more, all connected together--AND bonded to the house electrical system ground.
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KB4MB
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« Reply #28 on: July 08, 2011, 05:36:41 AM »

To me it was the cheapest of everything and makes me happiest that I did it.  I bough a roll of flashing for $30 at Lowes, I have six rods, everything is connected, and I am happy that I am protected (somewhat).  Also, the station seems to perform slightly better (but that is probably my imagination - when you sweat and pound rods in the ground, or do anything, it always seems to make your station better Smiley )
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AA4PB
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« Reply #29 on: July 08, 2011, 05:45:16 AM »

I had lightning strike a nearby tree and the surge welded the contacts closed on the garage door alarm switches. The radios, which are always connected and properly grounded, suffered no damage.

It would be rather inconvienent to disconnect 4 coax cables, a multiconductor rotor cable, a multiconductor remote switch control cable, plus a tuner control cable and pull them back through the conduit to leave them outside. Then unplug numerous pieces of gear. I could plan on spending an hour setup and teardown time each time I wanted to operate for a few minutes.
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