I recently installed a Superdish on a pole, my question is can I ground just the DP34 or do I need to run a ground from the dish itself to my grounding rod?
Grounding Dish?
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Many diagrams show a ground for the dish mounting itself in addition to the switch or grounding block on the coax. The dish itself is electrically isolated from the LNBF, so you can ground it without the risk of a ground loop. If the dish is on a metal pole in the ground, I wouldn't bother with an extra wire.
SimpleSimon said:
It's mounted on a steel pole that is cemented into the ground. Thanks for the info, I was planning on just grounding the DP34 but wanted to make sure it was going to be ok.
It could be true for plastic dish ( never use it ), but metal dish _have_ the connection to LNBF thru a small metal screw.SimpleSimon said:
That's not a real ground. In fact, the mounting screw bushing is probably isolated from the rest of the LNBF by the housing. Plus the screw itself is not making a good electrical connection with the dish arm.Smith said:
This is a good thing, avoiding ground loops on dishes that are grounded by their mounting to a different location than the switch or ground block.
Ground loops bad. Proper grounding good.
Is concrete sufficiently conductive to provide a good path to ground for the steel pole/Superdish? I seem to recall having to pound in a ground rod and use an 18" run of 0-guage copper cable to ground my Dad's TV tower I put in back in the '70s.
I'm not an expert, but it's always worked for me. I know there's lots of installers that don't even bother with a dish ground - just a cable ground. We won't talk about the fools that don't even do that.
Yes, there is some resistance due to the concrete, but remember, ground isn't really ground anyway - that's why ground loops occur.
Yes, there is some resistance due to the concrete, but remember, ground isn't really ground anyway - that's why ground loops occur.
Antenna grounds are designed to reduce static electricity buildup at corona points, which are the points that attract a lightning strike. There are no such thing to worry about ground loops with static electricity. The sole purpose of antenna grounding is to reduce the buildup of static charge, that is to keep it drained off to earth ground.
Therefore, the best way is to run a #6 or #8 aluminum or copper ground wire bonded to the mast to a ground rod driven into the ground as recommended for your soil conditions and area. Check with local building codes for recommendation. But generally reaching moisture in the soil is what is desired. I use 10 ft rods here. The idea of attaching any switching electronics to this ground is desired because it reduces static electricity buildup from less than direct hits. The kind of static electricity that will damage electronics but otherwise show no real visual damage other than fried IC's and stuff internally. The more contact points you make to the homogeneous metallic conductor the less risk you will have with static charge buildup in your system as long as that conductor is bonded well to a good earth ground.
When you do your own grounding system, yiou need to understand that there are three types of grounds. Electrical (the kind you have in your house wiring which is prone to ground looping); RF grounds (the kind like antenna engineers deal with to affect radiation patterns in broadcast and other communications), and the most unpredictable of all, static grounds that deals with corona point static charge buildups and causes the damage that most lay people will say- My phone modem got struck by lightning. A bit dramatic description to describe a few IC's that got zapped.
Most people are familiar with simple electrical grounds. A few are knowledgeable about RF grounds and ground planes, Few understand the whys and how to's of antenna staic grounding.
Having had a direct hit from a lightning bolt to a ham radio tower that was isolated from ground by design, I know the damage a direct hit can cause. It melted the base of the tower across the static guards, then lost structural strength and collapsed.
Therefore, the best way is to run a #6 or #8 aluminum or copper ground wire bonded to the mast to a ground rod driven into the ground as recommended for your soil conditions and area. Check with local building codes for recommendation. But generally reaching moisture in the soil is what is desired. I use 10 ft rods here. The idea of attaching any switching electronics to this ground is desired because it reduces static electricity buildup from less than direct hits. The kind of static electricity that will damage electronics but otherwise show no real visual damage other than fried IC's and stuff internally. The more contact points you make to the homogeneous metallic conductor the less risk you will have with static charge buildup in your system as long as that conductor is bonded well to a good earth ground.
When you do your own grounding system, yiou need to understand that there are three types of grounds. Electrical (the kind you have in your house wiring which is prone to ground looping); RF grounds (the kind like antenna engineers deal with to affect radiation patterns in broadcast and other communications), and the most unpredictable of all, static grounds that deals with corona point static charge buildups and causes the damage that most lay people will say- My phone modem got struck by lightning. A bit dramatic description to describe a few IC's that got zapped.
Most people are familiar with simple electrical grounds. A few are knowledgeable about RF grounds and ground planes, Few understand the whys and how to's of antenna staic grounding.
Having had a direct hit from a lightning bolt to a ham radio tower that was isolated from ground by design, I know the damage a direct hit can cause. It melted the base of the tower across the static guards, then lost structural strength and collapsed.
Excellent, Don! Thanks!
I knew there were differences in what grounds were supposed to do, but was never able to put it together before.
So, in real world installer terms, if a satellite dish is relatively low, and for example, has a well-grounded TV antenna mast above it, grounding the dish itself wouldn't be as important as say a roof peak mount where it's the highest conductor around.
What I'm getting at is: it looks like the objective is to drain static from the air around the device. The effective 'drain' area of a given ground probably depends on the air's humidity, with drier being smaller, yes?
Going off-topic:
I'd really like to know, as I'm about to raise a WiFi mast that'll top out at 65' AGL. Was planning on using 12-4 wire (because I have enough here) to connect the bottom of the mast (30' above ground in a tree) to a good pounded-into-the ground rod. The top of the antenna will be 10-20' higher than surrounding trees of the forest. The antenna cable itself is protected with a gas-discharge arrestor. Your thoughts are appreciated.
I knew there were differences in what grounds were supposed to do, but was never able to put it together before.
So, in real world installer terms, if a satellite dish is relatively low, and for example, has a well-grounded TV antenna mast above it, grounding the dish itself wouldn't be as important as say a roof peak mount where it's the highest conductor around.
What I'm getting at is: it looks like the objective is to drain static from the air around the device. The effective 'drain' area of a given ground probably depends on the air's humidity, with drier being smaller, yes?
Going off-topic:
I'd really like to know, as I'm about to raise a WiFi mast that'll top out at 65' AGL. Was planning on using 12-4 wire (because I have enough here) to connect the bottom of the mast (30' above ground in a tree) to a good pounded-into-the ground rod. The top of the antenna will be 10-20' higher than surrounding trees of the forest. The antenna cable itself is protected with a gas-discharge arrestor. Your thoughts are appreciated.
I love it when you like to make things "simple"
The real task here is to reduce the static charge buildup on corona points on the structure itself, not the surrounding air. While it is true that humidity lessens static electricity intensity, the differences between 90% humidity and 10% is not likely to result in much change in a direct hit. Besides you really can't control the humidity during the thunderstorm anyway because it is likely to be close to 100% The humidity issue has more to do with static issues in a room environment where when it's low, you are more likely to cause electronic circuit damage after walking across a nylon carpet and picking up a PCB or memory ship than if the humidity in the room were high.
Also, don't be fooled in the myth that trees surrounding your home being higher than your antenna make it safe. Not so. While the trees may take the direct hit, secondary branch strikes can and will find any structure including you walking across the yard when the strike hits. Speaking of which, never hide in a ditch as that can work like a concentrator, always lie flat on the ground face down arms and legs spread out. It will reduce your likelihood of getting struck. Get under a covered area as lightning likes to travel over the outside surface of any cover. That's why inside a car is good protection.
Your antenna- Think of it this way, You put some conductor in the air and allow it to build up static electricity due to wind blowing past it. Ungrounded it will continue to build until a cloud rolls by with rain and wind, that causes an opposite charge build up. When the cloud gets close enough to your mast (ungrounded and full of static charge) the two connect with a lightning bolt or charged air path to neutralize the two. Now consider that you connected that mast to a good earth ground and don't allow the mast to build up static E. The ground keeps draining it off. The cloud get's near by and keeps on going as the potential difference is not great enough to charge the air and discharge the potential difference. You can't control the static buildup in the cloud but you can control the static buildup in the antenna mast, hopefully enough to make the cloud ignore your antenna and the tree too.
Finally, you hope you have reduced the probability of strike and damage. I don't think it is possible to eliminate any possibility of a strike.
AS for the wifi mast itself. Isn't what you are planning illegal (FCC) ? I don't know as I have not looked it up but as a licensed FCC broadcast engineer, I suspect you would be in violation of some regulation regarding wifi transmission. Outside of my area though.
I have a wifi system here and simply added two WAP's for full coverage around the house. I don't see the point in what you are planning to do with such extreme "AGL" Educate me!
The real task here is to reduce the static charge buildup on corona points on the structure itself, not the surrounding air. While it is true that humidity lessens static electricity intensity, the differences between 90% humidity and 10% is not likely to result in much change in a direct hit. Besides you really can't control the humidity during the thunderstorm anyway because it is likely to be close to 100%
The humidity issue has more to do with static issues in a room environment where when it's low, you are more likely to cause electronic circuit damage after walking across a nylon carpet and picking up a PCB or memory ship than if the humidity in the room were high. Also, don't be fooled in the myth that trees surrounding your home being higher than your antenna make it safe. Not so. While the trees may take the direct hit, secondary branch strikes can and will find any structure including you walking across the yard when the strike hits. Speaking of which, never hide in a ditch as that can work like a concentrator, always lie flat on the ground face down arms and legs spread out. It will reduce your likelihood of getting struck. Get under a covered area as lightning likes to travel over the outside surface of any cover. That's why inside a car is good protection.
Your antenna- Think of it this way, You put some conductor in the air and allow it to build up static electricity due to wind blowing past it. Ungrounded it will continue to build until a cloud rolls by with rain and wind, that causes an opposite charge build up. When the cloud gets close enough to your mast (ungrounded and full of static charge) the two connect with a lightning bolt or charged air path to neutralize the two. Now consider that you connected that mast to a good earth ground and don't allow the mast to build up static E. The ground keeps draining it off. The cloud get's near by and keeps on going as the potential difference is not great enough to charge the air and discharge the potential difference. You can't control the static buildup in the cloud but you can control the static buildup in the antenna mast, hopefully enough to make the cloud ignore your antenna and the tree too.
Finally, you hope you have reduced the probability of strike and damage. I don't think it is possible to eliminate any possibility of a strike.
AS for the wifi mast itself. Isn't what you are planning illegal (FCC) ? I don't know as I have not looked it up but as a licensed FCC broadcast engineer, I suspect you would be in violation of some regulation regarding wifi transmission. Outside of my area though.
I have a wifi system here and simply added two WAP's for full coverage around the house. I don't see the point in what you are planning to do with such extreme "AGL" Educate me!
Thanks much again for the info - wish we could sit down over beverages somewhere.
Yes, I try to keep things simple, and usually get the job done - but when I ain't sure, I'm sure glad to have someone like you around.
I didn't think that the other trees would make me safe - in fact because it's higher, I thought I was in more danger, but grounding it should do the job.
Good advice on lightning safety. I live in the #2 lightning strike county in the USA - we try to get that info out all the time.
As for what I'm trying to do, yes, I believe I'm legal. My 'tower' is less than 100' - which I think is some sort of limit regarding such things. As for the actual radio side of it, I'm well within the 2.4GHz band's max EIRP of 36dBm (4w). Calc: AP to 500mw amp through 100' CNT-400 to 12dBi Omni yields 27-6+12=33dBm (actually less with pigtail & connector loss and such). The objective is a small neighborhood WLAN so a few of us can share my Direcway. I've already checked with DW - I was pleasantly surprised to find that they don't mind - they've got bandwidth throttles. Yes, Direcway ain't a lot of bandwidth (400k), but it's a lot more than dial-up (26k) out here.
Yes, I try to keep things simple, and usually get the job done - but when I ain't sure, I'm sure glad to have someone like you around.
I didn't think that the other trees would make me safe - in fact because it's higher, I thought I was in more danger, but grounding it should do the job.
Good advice on lightning safety. I live in the #2 lightning strike county in the USA - we try to get that info out all the time.
As for what I'm trying to do, yes, I believe I'm legal. My 'tower' is less than 100' - which I think is some sort of limit regarding such things. As for the actual radio side of it, I'm well within the 2.4GHz band's max EIRP of 36dBm (4w). Calc: AP to 500mw amp through 100' CNT-400 to 12dBi Omni yields 27-6+12=33dBm (actually less with pigtail & connector loss and such). The objective is a small neighborhood WLAN so a few of us can share my Direcway. I've already checked with DW - I was pleasantly surprised to find that they don't mind - they've got bandwidth throttles. Yes, Direcway ain't a lot of bandwidth (400k), but it's a lot more than dial-up (26k) out here.
SimpleSimon said:The objective is a small neighborhood WLAN so a few of us can share my Direcway. I've already checked with DW - I was pleasantly surprised to find that they don't mind - they've got bandwidth throttles. Yes, Direcway ain't a lot of bandwidth (400k), but it's a lot more than dial-up (26k) out here.
Simon,
I am on Dway, as well. I would be interested in knowing who told you they didn't mind you sharing the connection. I only ask since it's a violation of the subscriber agreement, and as such, I have turned down people who have offered a little on the side to share mine in such a fashion. It seems that it wouldn't be too different than receiver stacking, allowing others to use a service they haven't paid for (even if I'm not using it at the time, or not using the full bandwidth for my subscription).
3.4. SUBSCRIBER RESPONSIBILITY.
...
Permitted users of your account are limited to family members within your permanent residence.
....
Well, I'm on the Business package with a DW6000 & static IP, and that might make a difference, although I don't know why - there doesn't seem to be a separate agreement. Also, section 3.2 of the agreement limits use to the same household.
I called Direcway and asked what package I'd have to have to open a WISP (I'd seen some press release saying they were doing that). The CSR told me that it wasn't a problem - just do it. Maybe I just won at the game of CSR roulette, but I've tried to do it 'right'.
I called Direcway and asked what package I'd have to have to open a WISP (I'd seen some press release saying they were doing that). The CSR told me that it wasn't a problem - just do it. Maybe I just won at the game of CSR roulette, but I've tried to do it 'right'.
That's my position on it. We are sharing the expenses, but it certainly won't turn a profit.snathanb said:
The best solution! When it's feasible.gpflepsen said:I find it easier to just direct-bury CAT5e to the neighbor's houses.
Happy to do it if you bring the backhoe & ditch witch.
And oh yeah - we have to get easements from the county and at least 4-5 adjacent owners.Not raining on your parade - you ARE right, but it's just not possible here. Even if we were adjacent, it can be real tough to get a trench through the Pikes Peak granite.
User #1 is 700' NNE and +40'. User #2 is 500' ENE and +30'. User #3 is 600' SE and +40'. User #4 is 200' W and -20' in altitude.
Wireless is also a LOT less expensive than 2000' or more of DB cable.
Just to point out a couple things. The purpose of grounding the dish would be to give the lightning a low inductance path to ground which would be the only way to protect the dish if directly struck by lightning. Protection from static is of secondary concern.
http://www.satelliteguys.us/showthread.php?t=5159
Concrete is a good conductor of electricity (compared to earth) and steel re-inforced concrete can be a valuable part of a grounding system for an antenna. Considering the low cost of a DBS antenna, going through the effort of creating a perfect ground to protect it has diminishing returns.
Grounding the cable coming into the home is required per NEC and should be close to where it enters the home and tied into the whole house ground system. This is the minimum necessary to ensure human safety. To protect the components connected to the cable there are further steps you can take, again related to providing an alternate, lower impedance path to ground for the lightning to follow.
See the link above for a FAQ entry regarding such.
http://www.satelliteguys.us/showthread.php?t=5159
Concrete is a good conductor of electricity (compared to earth) and steel re-inforced concrete can be a valuable part of a grounding system for an antenna. Considering the low cost of a DBS antenna, going through the effort of creating a perfect ground to protect it has diminishing returns.
Grounding the cable coming into the home is required per NEC and should be close to where it enters the home and tied into the whole house ground system. This is the minimum necessary to ensure human safety. To protect the components connected to the cable there are further steps you can take, again related to providing an alternate, lower impedance path to ground for the lightning to follow.
See the link above for a FAQ entry regarding such.
Mke_H. Yes, a good ground will help direct lightning - but I like the idea of minimizing the risk in the first place - AS Don L. says. The FAQ you reference says it's NOT for static discharge. I disagree, but it doesn't matter - EVERYBODY (except for some incompetent, lazy installers) agrees that it's a good idea.
