GROUNDING THE SHACK

Hookin up those Audio Boxes without gettin yourself Perplexed.
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KD5TTZ
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GROUNDING THE SHACK

Post by KD5TTZ »

Hey you all.

I am going to try a little something here for grounding the radio, amp, rack and all that other stuff inside the room. Here is the idea, now I have seen something for sale like this in the books, but I am a cheap scape. If I can make one like it, I will.


Here at work we have a great deal of Diamond Plate Aluminum.
I wanted to get a piece of the aluminum and fab it with a 90 bracket system.
Attach it to the wall behind all the junk and use it for a central grounding station.

Coax will be routed to this and terminate into a Barrel connector. The connector will have a jam nut on each side securing it to the aluminum plate. The other end will go to or from the component to the antenna you get the picture.

Along with all the coax terminating the same way into this plate, all the grounds from the radio, amplifier, antenna tuner, antenna switch. will have their individual ground from component to this plate.

Once everything is connected to this plate, there will be a ground strap of some sort going through the wall and down to the 8 foot copper ground rod.

I will do the same thing for all the rack equipment, but not on the same ground.


How does this idea sound? I am sure this has been done before, but I haven't heard any comments on this, good, ot bad.

Please, if you have any comments, question, or advise, please post it.

Thanks,
God Bless
If it doesnt fit, don't forse it. Get a bigger hammer !

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w5cul
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Post by w5cul »

Kyp,

Manufacturing your own ground buss bar is the way to go. Copper would be the best material, but aluminum should work as well.

I would use at least 3 ground rods, spread no less than 8' apart from one another in some sort of a line. You are trying to create an RF ground, not just a DC ground. The more rod/cable/flashing surface exposed to the earth, the better the RF ground. Bond the rods using either copper flashing or a 00 cable that has been stripped of it's insulation and that is buried at least 3' deep between each rod. The copper flashing can be hand made as well. Go to home depot, purchase 1/2' copper tubing, cut it down the middle of one side, and flatten it out. As a matter of fact, you could do that to create your ground buss bar as well; better than aluminum.

I bonded my rods using 00 bare cable that I soldered onto the rods using a propane torch. I now wish that I had used copper flashing, but hindsight is always 20/20.

I would tie everything that has to do with your station, audio and all, to the same grounding point. I know, this may cause a 60Hz hum in your audio gear due to two differences of ground potential; 3rd plug house ground Vs Station ground. There are two ways to deal with that. Throw a lot of money at the situation by using transformers between each piece of gear, or, defeat the 3rd prong ground using cheater plugs from Home Depot, tie all of the audio chassis together, and take one ground wire to the station ground. Now it should be said that there are those who do not agree with the later statement, and it could be a source of potential harm to the careless inexperienced operator (dependent upon how the manufacturer wired their gear), but it is what some of us are doing none of the less.

The other alternative out there that is preached quite a lot is to bring your station ground and house ground to the same potential. This would involve bonding the two systems together, and some re-work on the house ground wiring; you can not forget that you would be battling the resistance associated with the length of the house ground wire in order to achieve the same ground potential between the two ground systems. To me, this would be a major undertaking, and even then, I personally doubt that you would gain much for it; keep in mind that the transformer that feeds your house is grounded to a ground rod plugged in the same ground that your station ground is plugged into.

Your mention of using barrel UHF connectors routed through your ground bar is a good idea. I thought about doing that myself, but I do not have enough room between the back of my ground bar and the exterior wall. Again, hindsight is always 20/20. If you do this, please try one antenna connected straight to the radio, record the S-Meter reading, and then re-connect through the grounded UHF barrel connector and see if there is a difference. I would love to hear about that. The other reason why I have not tried this idea is because when you draw it up electrically, you realize that you are creating a ground loop; ground bar to radio chassis, radio chassis to cable shield, cable shield to ground bar. I do not know if that will have any affect or not. I am still mulling around on how to isolate the cable shield from the ground bar to the radio efficiently; home brew.

Well, I hope this helps out. I know I may get pinged for the suggestion of cheater plugs, but at least I have the guts to admit what I am doing ;)

Later,

Mike
W5CUL

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Bow
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Post by Bow »

Cool Post Mike.

I have been wondering this myself, as I have a bit too much RF in the shack as well.

I run all the radio and Audio gear into the same power strip. All of the chassis grounds for the Transmitter, Antenna Tuner, and rack go to a single copper bar, through 1/2" tinned copper braid, and out to a grounding rod outside.

I am currently looking for a locate source for that UHF (SO-239) feed thrus so I can build a window feed-thru out of wood with some Aluminium or Stainless Steel plate for the actual feed thru, and ground that point.

I have the I.C.E. 303 U suppressors coming.

I am going to redo my rack arrangement and run from one box to the next and then into the mixer, instead of my current setup which runs the EQ and Compressor thru the mixer's Effects loop. This should give me shorter cable runs and less chance for RF...

I agree that the isolation transformer method is pretty cool, until you price it out.. ouch

I'm all for the low-buck building, anyone can buy stuff, few can build it...
Bow


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KD5TTZ
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Post by KD5TTZ »

W5CUL,
You stated to tie all grounds to one central grounding bus, then rout to the ground rods located outside. This I will do, then fight with the 60Hum.

Now the 3 ground rods outside. You stated that I should have them in some sort of line, at least 8' apart. Is it ok to bury the entire ground rod?

To make this with 3 rods in a line no closer than 8' I would have to bury everything. As this will be in the yard.

I have about 60' of #4 welding lead, would this be ok to use to ground the bus to the rods, and then connect the rods together using the same welding lead?

Thanks,
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Post by Voodoo Guru »

Yes, We agree,

RF grounding is slightly different then DC grounding.

DC grounding is always accomplished when using RF grounding techniques,

But...

RF Grounding is NOT always accomplished when using DC Grounding Techniques.

The trick here is to use the widest possible strapping when connecting equipment and the Ground rods.
Copper Flashing is the best.
We use 2" wide here.
What this does is create the least amount of Impedance to the RF energy to ground.

The next technique is to use what is called 'Star Grounding' for all the Equipment in the shack.
The typical Buss Bar type ground is not the optimum way to do this.
It is great for DC grounding but not so good for RF.
Star Grounding is accomplished like this.
Pick a piece of equipment that will be the center of the Hub (Star), this is usually the last piece in the RF line like the Tuner.
Then take a strap from each piece of equipment (rigs, Rack, amp) and run it to the Tuner.
The Tuner is the Central piece to tie everything to.
Then run the Copper Strap from the Tuner out to the Grounding Grid (or Rods) outside.

We have a Ground Halo around the Tower here. then from the Halo, there is a ground rod for every 8 foot to the other side of the house to the Electrical Utility ground. Each one of these ground rods including the Electrical utility is connected together as W5CUL described.
The reason 8 foot is used is because that is within the 'Sphere of Grounding Influence' the typical ground rod will have at 8 foot depth.
They must intersect each other.
If there is a separate ground rod for the Phone line, this is also connected to the Grid.
The secret is to make ALL the grounding points at the same potential.

Doing this will usually fix all the 60cycle hum problems.

We use the ICE devices at the base of the tower and are all connected to the Ground Halo.
This and the Grounding practices above cured 100% of all RFI and Hum in this location.

Granted, there is always an oddball device that might pop up, and special practices might have to be accomplished to alleviate any hum or problems.
We had to do the ground prong trick like W5CUL described on out Satellite Modem and the Computer to get absolute quite.
This was due to problems and noise coming from the power supplies of these devices into the Ground!
We could actually see the Ground Spike on the Oscilloscope!
The Mic preamps were picking up this power spike (sounded like a POP) coming from the Satellite modem power supply every time the Satellite Trea Transmitted a signal pulse.
Talk about a Bugger to find!!

Yes you can Bury everything, it just makes it difficult to service.
also the corrosion is a factor between the connecting cables and the ground rods.
We used some sprinkler covers that sit flush in the ground allowing the connections still to be accessible for maintenance and to keep them out of the dirt.
You can use the welding lead to tie the rods together, but just solid copper wire is sufficient, actually better as you will have less corrosion to deal with between the strands if buried.

One thing Mike that needs to be addressed with your Soldering of the Strap to the Rods.
This is GREAT for RF grounding purposes....but Horrible for Lightning Protection.
The Lightning pulse will vaporize the solder in an instant and you will have no protection, this will happen so fast that the rest of the lightning pulse will do its damage.
Thats why almost all grounding is done mechanically with clamps.

OK hope this helps some.
Take Care,
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KD5TTZ
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Post by KD5TTZ »

That explains a great deal about grounding.

I will do the Star technique first. What do you use for the Star? maening, the ground from each piece to the central Star (TUNER) 10 or 12ga. solid wire?
Or do you use strap?

I will be doing exactly what you described, and that should get me out of the RF and into the quietness of AIR WAVES.

What will this do for white noise? Will it lessen the noise any?

Thanks,
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Post by Voodoo Guru »

What do you use for the Star? maening, the ground from each piece to the central Star (TUNER) 10 or 12ga. solid wire?
Or do you use strap?
We use the Strap. The thinner and wider the better for Low Impedence to RF.
You can use the Tubing method that W5CUL suggested, we've found it to be a little thick though.
Other alternatives are copper roofing flashing, also you can get it from Radio Works.
We used some 8 foot long, 2" wide strips cut from thin copper sheeting at a sheet metal shop.
Any thin copper thats Flat and wide will work.
It doesn't have to be 2" wide, thats just what we wanted to use.
What will this do for white noise? Will it lessen the noise any?
Yes it might, but probably not.
The real improvement in White noise was when the ICE lightning arrestors were added to the coax lines.
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w5cul
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Post by w5cul »

Let's think about star grounding for a second; if you use the tuner as the center point and take all of your equipment grounds to the tuner, isn't that the same thing as using your ground buss bar as the center point and taking all of your equipment grounds to the ground buss bar? Both methods create a star grounding pattern, one uses a piece of the equipment as the focal point, the other uses the ground buss bar. The buss bar is my preferred method as each piece of equip has its own tie point on the bar; not to mention it is how we do it in the Telco world.

Mike, thank you for the tip on the lightening protection. I had no idea, and when I read your post, the proverbial light bulb went off. The idea of using sprinkler covers is too ingenius; sounds like a trip to home depot for me.

There maybe some mis-understanding on one of my suggestions regarding copper flashing; I do not use it to bond each piece of equip to the ground buss bar. Like Mike said, it is to thick and cumbersome to use in such an application. Using copper tubing, cut and flattened out into a a retangular strip (flashing) would be perfect to manufacture into a ground buss bar. Ground buss bar being a grounding point mounted on the wall behind the station that you connect all of your equipment to, and that is connected via wire/flashing to your ground rod system, . The homemade flashing would also be the cats meow for bonding the ground rods together.

Mike took the time, as opposed to my post, to get into the differences between DC ground and RF ground, and why you want the ground rods at least 8' apart. He is correct, you are trying to avoid the concentric circles created by the ground rods from overlapping too much. This will cause over saturation of the ground, and reduce the RF grounding affect. This is why you want the rods at least 8' apart. So with that thought in mind, for a 32' run on a ground system, in order to maximize the grounding affect along the whole 32' run, you would want to use 4 ground rods spread at least 8' apart bonded together. You would be surprised what such a ground system can do for your radiated signal on HF.

I have yet to install lightening arrestors, and I to should get the ones that Mike suggests. I have heard nothing but good word about them, and how they can quite your receiver down.

Well, it looks like you have all the info needed to create a hell of a ground system, and defeat any 60Hz hum along the way. Problem with all of this info is that it involves digging. I played hell here in Austin installing my ground system. Not only did I do it during the summer time, what a dumby, but we have lots of rock just about 3' below the soil. So it was a B*tch driving the rounds and digging the trenches, all the while managing my introvenious saline drip required to keep from getting dehydrated ;)

Good luck with your project, and let all of us know how it went!

Later,

Mike
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Post by Voodoo Guru »

mmmmmm....
Good Point.
Guess we just like the last piece of equipment with High RF potential (Amp or Tuner) to be the Focal point, then straight to ground from there, instead of having to go back to another focal point with it then to ground.
Mike's right though, both techniques should work just fine either way.
We prefer the 'last piece of Equipment' technique here.
So it was a B*tch driving the rounds and digging the trenches, all the while managing my introvenious saline drip required to keep from getting dehydrated
mmmm.....NOW that explains why you seemed so 'Touched' Mike!!!!
That misplaced LOVE for those Yazoos makes so much sense now!!!! :twisted:
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Post by w5cul »

HAHAHAHAHA.....we all have our quirks, some of us worse than others Mr. Kennywood ;)

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Post by w5cul »

Well, I finally ordered and installed a 303/U. Let me just tell everyone it is the cats meow!!! On the average, my noise floor dropped by 2db; I caught myself troubleshooting my RF gain because the typicall hiss didn't sound loud enough. Those pesky little static crashes, well, I do not think there is anything on the market that can completely take those bad boys out of your reciever. But the 303/U does a good job of shunting the energy to ground thus attenuating them, which is a plus in my book!!

So for all those lurkers out there who have been reading our beloved Voodoo Forum, do yourself a favor, buy an I.C.E. 303/U and install it. It will definitely put a smile on your face.
W5CUL

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Bow
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Post by Bow »

w5cul wrote:Well, I finally ordered and installed a 303/U. Let me just tell everyone it is the cats meow!!! On the average, my noise floor dropped by 2db; I caught myself troubleshooting my RF gain because the typicall hiss didn't sound loud enough. Those pesky little static crashes, well, I do not think there is anything on the market that can completely take those bad boys out of your reciever. But the 303/U does a good job of shunting the energy to ground thus attenuating them, which is a plus in my book!!

So for all those lurkers out there who have been reading our beloved Voodoo Forum, do yourself a favor, buy an I.C.E. 303/U and install it. It will definitely put a smile on your face.
I agree 100%

Best money I spent so far.
Bow


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