kbloch wrote:The NxN will allow us to use two radios on the same antenna each with different frequencies.
And I would agree with that (redundancy against interference with 2 radios) if WISPs would do better grounding.
Over half of our RMAs are from damage that is clearly from lack of proper grounding. If WISPs deploy NxN for redundancy they need to step up their grounding practices.
From what I am seeing is if there is a Static Discharge, ESD Discharge, or ground potential shift both radios blow out their Ethernet ports. I mean you would achieve redundancy for spectrum interference but not from surge type damage.
I really wish WISPs would get more into proper grounding practices like cell carriers do which is where I learned it from.
1) Tower grounding system MUST be bonded to Electrical Service Ground else your Ethernet Cable is the bond. - VERY BAD
2) You can not rely on a steel tower being your ground run for several reasons so you NEED a dedicated "copper" ground cable run like #2 Green.
- A) Wire is made from copper because of its relatively low resistance, steel towers are a much higher resistance.
- B) Steel towers are usually multi parts bolted together and the connections are usually not good electrical connection.
- C) Surges from Static, ESD, or ground potential shifts will take the shortest less restive path like your Ethernet cable.
3) Ground Bus Bars should be installed on insulators. The reason for this is you do not want to try and drain current from the whole tower just the steel in the area around your antenna/radios. This is why Busbars are on insulators even though a wire from them may go 10 feet and clamp to an antenna. You want as much current as possible to take the path of the tower so if there is a charge on the steel 20 feet below your bus bar most of that current will flow down the steel rather then travel up the steel to get on to your grounding system.
4) Service loops on your Ethernet are there primarily to increase the distance of the Ethernet cable to Earth ground raising the resistance of the Ethernet cable making it less attractive to surges. You can go through a lot the calculation to determining the resistance of the intended ground path run and then calculate your needed Ethernet cable length to insure the intended ground path is shorter and less resistant or I as a rule of thumb increase the Ethernet cable run with a service loop to be 10% longer than the intended grounding system run to Earth Ground.
5) You should use #6 Green to lug to every antenna mount, I use a lug and put it on the antenna clamshell bolts with conductive anti corrosion paste.
6) If your radio has a ground lug use it. I use #6 with a small lug for some radios but I also use smaller 10AWG & 12AWG for radios with small ground lugs.
7) Towers need multiple ground rods spaced apart all connected to the master ground busbar at the base of the tower. The ground rods much reach VIRGIN CLAY SUBSOIL as that is where the Earth Ground Plane is because clay contains the conductive mineral. If you are on a rocky site look into supplementing your ground rods with chemical ground kits.
8) Run #2 Tin if buried or #2 Green if above ground to your service ground rods and a ground busbar in/on your equipment box. Make sure to ground everything that has a ground lug in your box
9) Grounding systems need maintenance too. Every spring check your ground bus and connection to insure the connection are corrosion free and everything looks good.
Here are 2 EXCELLENT posts on proper grounding:viewtopic.php?f=30&t=188viewtopic.php?f=30&t=1429Proper grounding was one of the best things I learned for my WISP!
We have sold around 11,000 switches and we are on RMA 133, of these 133 RMAs maybe half were from something stupid like corrupted flash, failed power supplies, firmware upgrades, or simply valid failures but the rest are from surge damage that could have been prevented with proper grounding.
Oh and we have had a few come in for RMA with dead bug guts that shorted out chips. SERIOUSLY keep bugs out of your boxes especially Ladybugs.
I hate having to tell people their switch damage is not covered under warranty but I especially hate it when they know the damage was from a storm and claim it came DOA or something.
In the one post above I tell the story of Sprint removing the grounding system and we started losing equipment on that tower, we had NEVER lost equipment on that tower and now that the grounding system is replaced we are back to normal.