Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: Use Braid or Wire for Ground outside?  (Read 9786 times)
KB4MB
Member

Posts: 295




Ignore
« on: October 04, 2010, 05:22:17 AM »

I am just so confused due to the enormous conflicting information.  I have never run a station ground, but I decided to put one in, just in case.  I am going to use braid from the tuner, rig, and the noise canceller unit I have.  This goes to a 2 foot copper bar on the desk.  Then from the bar to the service ground which is directly on the opposite wall of the shack (4 foot run). 

From the bar to the service ground, should I use braid or wire?  Then from the service ground I planted two more ground rods, about 15 ft away from each other (30 ft total distance)...  One is where the feedline drops from the loop so I can add a static bleed off on the balanced line, and then further away still to help dissapate anything.  From the service ground to these two rods, should I run braid or cable?

I assumed braid for all of it, but I wanted to be sure.

Thanks in advance,
Kris, KB4MB
Logged
KB1NXE
Member

Posts: 363




Ignore
« Reply #1 on: October 04, 2010, 12:12:22 PM »

Neither if you can.  Wire as a second choice. 6Ga at the minimum, larger is better.  Your first choice should be at lease 1 1/2" copper strap.  It is lower in impedance due to the skin effect.  Tinned braid is not all that low impedance as the current is flowing through the tin and not the copper.  And braid in general will form hundreds of potential points of rectification due to oxidation wherever the individual wires cross.

A good source of copper strap is Georgia Copper.  Click the ad that runs here on eHam. 
Logged
K9KJM
Member

Posts: 2415




Ignore
« Reply #2 on: October 04, 2010, 10:18:30 PM »

I agree.   Wide flat copper strap is the ground conductor of choice.
Usually also available at many discount home supply stores in the roofing department as copper roof flashing. Smaller stores may have to special order for you. (Last time I checked, A 6 inch wide by 10 foot long roll cost just under 40 bucks.  With a tin snips that can be cut down to make two 3 inch wide strips for 20 lineal feet, Or 40 lineal feet cut once more down to 1 1/2 inches wide.)

Another great conductor can be found in the same store in the plumbing department.  Soft flexible copper tube. 3/8" copper tube makes a very nice ground conductor, BUT care must be taken to not kink it.
Logged
KB4MB
Member

Posts: 295




Ignore
« Reply #3 on: October 05, 2010, 04:40:09 AM »

And what about inside the shack?  How do you attach the flashing and still be able to move around the equipment if you need to?  I was going to use braid here to a copper pipe, and then something to get outside...

From the pipe out, how can I get the large flashing through a wall?

Outside, how do I attach it to ground rods?

Sorry to be dense about this...

I use balanced line here, but I figured I should improve my ground situation (none at the moment).  Really, the only RF I get is on my noise canceller unit, and sometimes in my headphones... I plan on upgrading my interconnects this weekend. 

So, why bother?  I might decide one day to try 160, and if I tie both ends of the twinlead together, if I had a good ground, I might be able to actually get a signal out! Smiley  Also, just for peace of mind, though I know the powercord is good enough for safety, but I'd rather err on the side of caution.
Logged
KB4MB
Member

Posts: 295




Ignore
« Reply #4 on: October 05, 2010, 11:28:40 AM »

Or, how about this... connect braid (1") from equipment to ground bar (1-2 feet max run from equipment), down to BRASS ALL THREAD (about three feet run), through the wall, to 2" flashing outside to utility ground, then to ground rods that are outside...

Does this sound like an acceptable RF ground situation?

Reading all the info has my head spinning, of course - nobody agrees, or some have impractical solutions (I'd rip my hands off if I went behind my equipment with the copper flashing!)
Logged
K9KJM
Member

Posts: 2415




Ignore
« Reply #5 on: October 05, 2010, 11:10:56 PM »

The flat copper strap is easy to get indoors, As it can be bent into most any shape you want. But of course, There should be no sharp bends....  Once indoors, The copper strap goes to your "Single Point" ground panel where any coax switches, Lightning arrestors, etc are mounted to. (Some of the wide flat copper strap screwed to a piece of 3/4 inch plywood makes a dandy ground panel.)

Soft copper tube of around 3/8" diameter also makes a nice ground conductor IF you are careful to not kink it.   To make connections, You can just hammer an end flat and screw it to the strap, Or better yet, Use some hard silver solder (Flows with MAPP gas torch)

None of the radios in my shack are grounded with that little wing nut on the back......  That is just a good way to create ground loops....
I am talking about proper lightning protection grounding......

And most will tell you that if you need an "RF" ground, You have something wrong with your antennas.......   

(For info on low cost lightning protection: http://www.scribd.com/doc/14868226/lightning-protectiontaming-thors-thunderon-a-budget

Give that site plenty of time to load)
Logged
W0BTU
Member

Posts: 1852


WWW

Ignore
« Reply #6 on: October 05, 2010, 11:57:22 PM »

Just go to www.w8ji.com and look at his grounding advice. It's spread across several pages, and it's as good as it gets.
Logged

W5LZ
Member

Posts: 477




Ignore
« Reply #7 on: October 07, 2010, 07:56:33 PM »

There's nothing particularly beneficial about using 'braid' as a ground conductor.  It's handy, there's usually some 'extra' coax that can be used to get the braid from, it's flexible, and easy to solder to.  It also has some definite disadvantages.  In my area the weather can 'eat' up braid quicker than you might believe.  That's indoors too, not just outdoors.  While flexible can certainly be nice, it can also be a bit rough to keep it still, not 'wiggle' into something it shouldn't.
A fairly good idea is to use whatever you happen to have that will serve the purpose.  If it's copper it's easier to solder to, that helps.  But there's always mechanical connections that work well also.  A sort of 'heavy' currnt carrying capacity is a nice thing, which typically means bigger is better to some ridiculous point.  The old copper flashing used on roofs, chimneys, etc, works well, isn't all that difficult to use, and if you're a fair scrounger, you can find that stuff almost anywhere.
Fixating on using copper braid isn't exactly the best way of doing things.  Probably won't hurt, but there's nothing 'magical' about braided straps for grounds.  1/2 inch re-bar will work too, just a bit harder to deal with.  Unless you happen to have several miles of it, then why not??
Paul
 
Logged
KB4MB
Member

Posts: 295




Ignore
« Reply #8 on: October 08, 2010, 04:41:07 AM »

I went and bought the flashing, and you are right... for some reason I thought it was very rigid like regular flashing - and I was wrong! This stuff would have a tough time cutting bread let alone anything else.  I will be using the flashing for the rigs and equipment to the copper bus bar pipe at the desk, #4 to outside and the first bond to the safety ground outside, then flashing the rest of the way, just barely buried to the two other ground rods.  I think this, for my situation, will give me the best ground that I can do logistically.

I don't really expect it to do anything, noise wise, but I am prepared to be pleasantly surprised!! Smiley

I get barely some rf in the cans when I have it hooked up to my scaf filter - just need a choke for the lead going to unit - and I have some rf that lights up the led in the mfj noise canceller - I suspect better coax jumpers will fix that, but we will see this weekend.  I plan on upgrading the ground Saturday, and making better jumpers in the next week or two.

Thanks for everyones help!
Kris, KB4MB
Logged
K9KJM
Member

Posts: 2415




Ignore
« Reply #9 on: October 08, 2010, 11:01:11 PM »

Oh oh........    The copper flashing we are refering to should be about .020" to .025" or so thick.....   (About twice the thickness of a paper match book cover)   Depending on how hard your bread crust is, The flashing I use WILL cut the bread.......

I hope you did not get just some decorative type cover material.....
(Which would still be just fine as an RF conductor, Just no good for a lightning protection conductor.....)

Logged
KB4MB
Member

Posts: 295




Ignore
« Reply #10 on: October 09, 2010, 03:04:32 PM »

Well, it's out there, whether I did it right or not, or if it is thick or not.  From what I looked up, the stuff I bought was thick enough, but I don't know... it was meant for roofing material.  It isn't thin, but I would say it was about the thickness of a match book cover, maybe more.  The scissors I have can cut thick wire, so that is what I used (they are utility scissors, not just for paper - think poultry shears)...

No big deal either way, it was to dissipate rf for the most part, safety for the second part, and lightning as a last goal.  There are trees in the yard bigger (no guarantee of anything), the feedline would be toast before anything remotely tied into the ground setup I have.  However, induced voltage would be more of a concern, and I think what I have out there would handle that.  If I was using a tower, I'd be more concerned - running a 14g loop with twinlead - everything would evaporate before I even had a chance to think about what to do with the bolt - induced is more in the realm, and the spark gap I plan on getting SHOULD help with that (or not, but better than nothing).

I do disconnect feedlines and power when not operating.  The ground will have to stay connected now, though.  I hope that is ok...

Now, did it make any difference in the shack all this work?  Absolutely not. Smiley  Didn't think it would, but I wasn't really having problems anyway - just wondered if the noise floor would get lower, or if stray birdies or something would go away - It didn't...  I only have three or four birdies anyway, and I think they are the power supplies (never bothered hunting anything down)...  If it did make any difference, it is super subtle - however, tuning seems to be harder to get a perfect match as quickly before (I used to ballpark it relatively easy),  but I can get 1.1:1 on bands I couldn't before... have to do more investigation...

Thanks for the advice, everyone.
Logged
W5LZ
Member

Posts: 477




Ignore
« Reply #11 on: October 10, 2010, 05:09:16 AM »

Got some 'wide' flashing, don't feel like cutting 40 yards of it in half?  Fold the stuff, it works.  All kinds of options, just depends on what's easiest for you.
If this is a safety ground (lightning), then mechanical connections instead of soldered ones!  They don't hurt for RF grounding either, just not as 'necessary'?
Wanna seal all that stuff?  Paint it pink.  Works every time!
Paul
Logged
KB6YH
Member

Posts: 43




Ignore
« Reply #12 on: October 13, 2010, 08:42:56 AM »

The skin effect increases with frequency. At 60Hz with braid it would be not an important factor. At higher frequencies it becomes more significant. The braid seems to conduct well when in the coax at HF. I'll take a wild guess that braid is OK for a station ground.
Logged
N8CMQ
Member

Posts: 403




Ignore
« Reply #13 on: October 26, 2010, 07:47:50 PM »

I had a situation where several bud cabinets were giving pokes...
Bonding the cabinets together with 18 gage wire took care of the problem...
Use an ampmeter to see if you have any significant current on your equipment...
No RF was involved, but 400 Hz and 60 Hz potential differences, otherwise known as ground loops...
The latest technology is to use single point grounding. Also, I use LONG ground rods, as my water table is very deep and my soil is sand.
Logged

N8CMQ   Jeff
KG6YV
Member

Posts: 517




Ignore
« Reply #14 on: October 28, 2010, 05:50:40 PM »

three or four inch copper strap is the only way to go.  Your design with multiple rods with good spacing is a good one.  Why not take advantage by using copper strap.  It has much lower impedance.   

Greg
Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!