January 24, 2012

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Grounding 101  

Grounding one's station, feedline and antenna are some of the first things we learned to do as hams; yet not many of us do a good enough job at it today. We'll be discussing the different approaches, techniques, tool, products and benefits of doing a good job at being "well-grounded hams"!

73,
~George N2APB & Joe N2CX

Audio Recording ... (Listen to MP3 recording

Text Log from this week's session ...

<20:06:44>"George - N2APB": "Grounding 101"  ... see our web page for discussion notes this evening ... http://www.njqrp.org/teamspeak/Jan%2024.html
<20:08:45>"Tony WW2W": When and where should we have an earth ground separated with a chassis ground? (connecting them with caps here & there)
<20:12:24>"George - N2APB": Bruce, are you online and able to talk this evening?
<20:13:45>"Bruce - N1RX": will be available shortly.
<20:16:09>"George - N2APB": Important Basics: (1) Grounding bar for the bench, (b) Grounding rod closeby outside, and (3) Large sheet/mesh under foot or rug to establish the RF ground potential
<20:21:27>"Ray K2ULR": The safety ground at my QTH is less than 1 foot from the foundation.
<20:24:17>"Chris - w0anm": I bond to all the ground points,  power ground, two station grounds, and direct TV ground, so I agree with George.
<20:26:09>"Bruce - N1RX": Corner bar?
<20:26:21>"Ray K2ULR": <http://www.georgiacopper.com/>
<20:26:47>"Terry WB4JFI": Copper bar is too expensive for Lowes
<20:26:57>"KD8FMX - Dave": instead of putting a 6 ft copper pipe thru the wall why not use a ground rod 8 to 10 ft going thru the wall horizontal. it should provide good ground without the vertical rod
<20:28:28>"George - N2APB": Leaks?
<20:29:33>"Frank N3PUU": I believe I shared this link last week.  The motorola R56 manual.  Perhaps a bit overkill for the home station, but great reading and the principles certainly apply: http://www.radioandtrunking.com/downloads/motorola/R56_2005_manual.pdf
<20:34:06>"Terry WB4JFI": At the TV station I worked at (WTOP/WUSA), we had three-inch wide flat copper bus interconnecting everything (like in the W8JI website).  WE were co-located with the tower, and took a lot of lightning hits.  Very few problems.
<20:34:59>"Dave AA3UR": WRAL TV used a roll of 12" copper flashing running to all the racks in the station.
<20:36:14>"KD8FMX - Dave": alnox is a good electrical dissimilar metals coating
<20:37:18>"George - N2APB": MAPP gas flame instead of butane or propane?
<20:37:45>"Dave AA3UR": It is in yellow cylinders
<20:38:07>"KD8FMX - Dave": can cadweld be bought?
<20:41:18>"Joe - N2CX": The CADWELD process is a high temperature Welding/brazing process
<20:43:42>"KD8FMX - Dave": ebay has ultraweld (cadweld) 10 pack for 16.00
<20:44:19>"Terry WB4JFI": I bought a roll of 3ounce, 8-inch wide, 20ft roll of copper flashing as well at Home Depot or Lowes.  Not too expensive.  Made by Top Cop.
<20:45:56>"John-KJ6CVB": Home Depot 10' 12"-flashing to 8'rod
<20:46:29>"George - N2APB": How expensive Terry?
<20:46:50>"Terry WB4JFI": I dont remember right now.  Will check web site...
<20:48:28>"Joe - N2CX": Dissipative ground connection
<20:48:58>"KD8FMX - Dave": I have a friend K8li Has a 200 ft tower in ohio he recommends 6 ground rods going around the tower tied to the tower and to each other
<20:49:04>"Terry WB4JFI": Lowes has 8inch by 20ft roll for $37.92  (Amerimax)
<20:49:49>"Terry WB4JFI": 20ft, 10-inch roll for $48.98
<20:50:17>"Dave AA3UR": HD 12 " by 20 feet $58.00
<20:50:25>"Joe - N2CX": Yes it is NEC
<20:52:58>"Joe - N2CX": Ball gap arrestor
<20:53:14>"KD8FMX - Dave": arrester
<20:53:41>"KD8FMX - Dave": spark gap or gas filled arrestor
<20:55:55>"KD8FMX - Dave": even with his elaborate ground and polyphaser K8LI lost two radios and a computer from a tower strike
<20:56:50>"Joe - N2CX": MOV
<20:58:00>"KD8FMX - Dave": I always unhooked my antenna and shorted it together and to ground then hooked it back up after the lightning passed.
<20:58:37>"KD8FMX - Dave": I think that is the same as the gas filled arrestor
<21:01:21>"Terry WB4JFI": too bad we can't send RF through fiber optic cables (hi).  My antennas are always totally  physically disconnected, unless I am in the shack.
<21:02:31>"KD8FMX - Dave": using the switch still allows the lightning to conduct into the rig from localized arcing in the switch box. that is why I completely disconnect the coax and short it to ground
<21:02:48>"George - N2APB": Agreed
<21:04:43>"KD8FMX - Dave": Absolutely
<21:05:37>"KD8FMX - Dave": bulkhead connector with a copper plate that replaces a window, then grounded
<21:09:54>"Joe - N2CX": Coax switches from DX Engineering ar ~~ $00-$500
<21:10:48>"George - N2APB": http://www.dxengineering.com/
<21:11:32>"Joe - N2CX": DX Engineering also has grounding accessories
<21:11:40>"KD8FMX - Dave": lightning can cause carbon tracing that will make it a worse situation on any additional strikes. so replacing the entire switch as opposed to repairing it . sometimes you can not see a carbon trace.
<21:12:11>"Ray K2ULR": Don't forget cleaner audio.... important for digital modes.
<21:12:42>"George - N2APB": Great point Ray
<21:12:54>"Frank N3PUU": another good source for metal, etc is Fazzios in Glassboro, NJ and New Castle, DE.  Surplus metals can save some serious money..
<21:14:03>"KD8FMX - Dave": omnisource may be a good source for copper or aluminum plate.
<21:14:41>"George - N2APB": DX Engineering's "grounding" products ... http://www.dxengineering.com/default.asp?DeptID=19
<21:16:17>"George - N2APB": Lightning protection articles on DX Engineering site ... http://www.dxengineering.com/techarticlepopup.asp?ID={A0896F49-0C15-4885-9969-EC0AB4B210F8}
<21:19:42>"KD8FMX - Dave": I am sure the hotel did not appreciate the hole
<21:21:25>"KD8FMX - Dave": gutter antennas seem to work well too.
<21:24:24>"Joe - N2CX": Don't drop a wire down a building.  The folks on lower floors complain to the management...
<21:25:22>"Joe - N2CX": A mil-spec modem would not have RF interference problems
<21:25:47>"Terry WB4JFI": Not directly related, but I have put Sycom SYC-120/240-T2 whole-house surge protector in breaker box.  Electricians wanted $400, I found it for $55 on ebay, and paid an electrician a few dollars to install while doing other work.  Good for surges through AC power line, not a direct lightning hit.
<21:26:42>"KD8FMX - Dave": any one know about the adtrx-2
<21:27:04>"George - N2APB": Heard good stories (and value) of doing this too.  Never got a Round Tuit here though.
<21:29:11>"KD8FMX - Dave": US navy has a great article about mag-res loop antenna for weak signal and high magnetic noise areas!
<21:29:58>"Joe - N2CX": Source for Navy loop antenna?  I've done it professionally for USAF
<21:31:15>"KD8FMX - Dave": put a tag on the antenna cable that alerts you that the antenna is disconnected so you do not transmit w/o antenna hook up
<21:32:08>"Terry WB4JFI": I put a sticky note on the rig front that says "NO ANTENNA" as a reminder

Session Notes ...

STATION FEEDLINE ANTENNA
  • Cold water pipe
  • Electrical outlet ground :-((
  • All equipment
  • Braid or ground bar running at rear of table
  • #__ ga cable going to ground rod
  • Disconnect switch
  • Ground the (coax) shield at both ends
  • Coming into house
  • Spark Arrestor
  • Ground Rod(s)
  • Ground radials
  • Ground plate
  • Stainless steel
  • Buried radials
  • Elevated radials
  • Counterpoises
  • Tower grounding

 

 

Problems if things are not well-grounded

 

Special cases:

 

Lightning Protection!

 

Products:

 

Don Butler, N4UJW Hamuniverse.com ...
"
You will also need to install a good station ground just outside the entry point of the coax. Get a good copper ground rod, 8 feet long and drive it into the ground just outside the entry point of a window or where it enters your shack. Keep in mind that the distance from the ground rod should be as short as possible from it to the equipment inside. It is never a good idea to have a long distance from the equipment to the ground rod ... remember: as short as possible. Now run very heavy (large conductor like # 8 size) if you can get it or as large as you can afford. The idea here is to have the least resistance to current flow as possible. The larger the wire the less resistance. The longer the wire, the more resistance is usually the case. Connect all of your equipment using whatever connectors needed to this single ground wire using short lengths if possible. Use the largest size wire that will fit the ground connections of your equipment.  It is also advisable to install a surge protector with several AC outlets on it for AC power connections for your station equipment.  Use metal water pipes as an alternate ground if you don't have access to a ground rod. Install a switch in the antenna coax that switches the antenna to ground if at all possible. This helps with lightning protection."

 

 

Reference Links

Pics from good W8JI website ( http://www.w8ji.com/ground_systems.htm  ) ...

 

      

 

  

 

 

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