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Need to know IF frequency used between antenna and modem.

Sophomore

Need to know IF frequency used between antenna and modem.

Because Ilive in the lightning capitol of the U.S. the SOP here is, all services entering the home shall be connected to a U.L. listed surge protection device (SPD).

As such I need to know the frequency(s) of the signal(s) passed between the modem and the antenna, so I purchase the correct SPD to provide that protection.

I have searched the web as best as I can, but so far have not been able to find this information listed anywhere, apparently this is not  common practice.

If anyone could supply this information it would be greatly appreciated.

Thanks in advance.

Wayne

 

 

 

 

 

 

 

 

 

15 REPLIES 15
Associate Professor

Re: Need to know IF frequency used between antenna and modem.

The transceiver on the dish's boom is grounded, but clearly that's not protection from surges. Good question.


* Disclaimer: I am a HughesNet customer and not a HughesNet employee. All of my comments are my own and do not necessarily represent HughesNet in any way.
Assistant Professor

Re: Need to know IF frequency used between antenna and modem.

Not sure HughesNet recommends any SPD on the coax itself and if they have even tested them. Only time I see it being useful is a very close strike to the dish. Even then may not (probably won't) protect the radio. Induced voltage and current from a close strike will fry most small gauge ground wires. It is cost prohibitive to install the wire gauge and ground rod depth for true protection in a home environment.

 

http://urgentcomm.com/techspeak/radio_wellgrounded_principles

Moderator

Re: Need to know IF frequency used between antenna and modem.

Hi WT4FEC,

 

Interesting question. I will get with the appropriate person here in our office to get you an answer.

 

~Amanda

Associate Professor

Re: Need to know IF frequency used between antenna and modem.

To be honest, while it's typically suggested NOT to install one of these blocks... It would be nice being able to have an option to do so for those that have either many dishes, or frequent strikes in the area...  Though, such devices rarely actually work.

Associate Professor

Re: Need to know IF frequency used between antenna and modem.

While it's nice to protect the devices hooked up to a surge protector like you would for indoors, the main thing is really to try and prevent such surges from any kind of external antenna entering the house and potentially causing a fire. It might not save any external transceiver equipment, but it will save the house.

 

I have a 100' longwire that goes between two trees (for a Drake R8a and JRC 535D, just for WT4FEC's benefit). The coax to the house is grounded, but the only other "surge" protection I have is a balun at the wire, which really isn't any protection at all. Scares the bejesus out of me every time there's a lightning storm that the only thing I can do is unscrew a connector that's already inside the house and put it in a glass jar to try to isolate it.

 

Edit: Apparently the lawn guys have managed to cut the coax I buried... so... max nixt. lol


* Disclaimer: I am a HughesNet customer and not a HughesNet employee. All of my comments are my own and do not necessarily represent HughesNet in any way.
Sophomore

Re: Need to know IF frequency used between antenna and modem.


@BirdDog wrote:

Not sure HughesNet recommends any SPD on the coax itself and if they have even tested them.

 

Technically under the National Electrical Code, NFPA 70 810.20(A), Hughsnet installers are required to install a Antenna Discharge Unit, which is a basic sparkgap coaxial protector with about a 400 volt breakdown level, these are commonly used in CATV, DISH and pre-AT&T DirecTV installations.

 

Depending on the IF frequency, I will probably use a TII gas tube SPD which has virtually no loss (less than .1 dB) up to 3 GHz, these are what AT&T is not requiring DirecTV installers to use. 

 

Only time I see it being useful is a very close strike to the dish. Even then may not (probably won't) protect the radio.

 

Actually with a layered system of SPD's and secondary coaxial grounding, protection from direct hits can be provided, our cell sites down here take hundreds of direct hits and most times the BTS's are not damaged at all. 

 

Induced voltage and current from a close strike will fry most small gauge ground wires. It is cost prohibitive to install the wire gauge and ground rod depth for true protection in a home environment.

 

I disagree, the code requires a number #10 copper grounding conductor which only costs $.21 per foot, however for grounding and bonding I use #6 which is only $.51 per foot, so for an adverage instalation lets say 30 feet the total cost would be $15.30 for the conductor and if the subscriber had an older home which lacked an Intersystem Bonding Connector and additional $9.50 for a 8 foot ground rod + $2.18 for a teardrop ground rod clamp, so out the door we are talking $27 for a system that can provide a very good level of grounding and lightning protection protection, which is not a lot to spend when the cost of a modem and a TRIA is considered.      

 

However some of us, espically those who live in,the lightning capitol of the U.S.A. take things a little more seriously.

 

My ground system began with the code required grounding electrode installed by the builder, to that I added a #2 bare copper ground ring that is trenched in 18" to 24" below grade, which encircles my home, that ground ring has 4, 8 foot ground rods one at each corner with 2 additional intermedate ground rods to ensure there is no more than 70 feet between grounding electrodes.

 

In addition ther are 2 more ground rods, one on each of my towers, another for my shop which is ajacent to my home and another one out on the gate controller which is out by the road and since that is 315 feet from the home that deadended ground conductor has 4 additional ground rods on the run so in the end I have a total of 14 ground rods and about 1200 feet of direct buried bare copper gounding conductor. 

 

The grounding system was designed using a combination of my employers practices ATT-TP-76416-001 Grounding and Bonding for Network Facilities, Motorola R56 Standards and Guidelines for Communications Sites and the NEC.

 

https://ebiznet.sbc.com/sbcnebs/Documents/ATT-TP-76416-001.pdf

http://www.ronet.co.za/downloads/R56%20Guidelines.pdf

 

As for SPD's my fist layer are at the source be that a dish or a tower mounted antenna.

 

Tower ground.jpga1.jpg   

 The smaller ground bar is for the DISH antenna the larger bar holds 4 PolyPhaser SPD's for a local UHF repeater, the SPD's in the NEMA box are for my 2 meter antennas.

Backboardgnding.jpg

Inside my ofice a second ground bar provides coaxial shield grounding

 

And all of these grounding points are bonded to the ground ring.

Wayne 

 

 

 


 

 

 

Sophomore

Re: Need to know IF frequency used between antenna and modem.


@Amanda wrote:

Hi WT4FEC,

 

Interesting question. I will get with the appropriate person here in our office to get you an answer.

 

~Amanda


Thank you very much.

 

Wayne

 

Associate Professor

Re: Need to know IF frequency used between antenna and modem.


@WT4FEC wrote:

However some of us, espically those who live in,the lightning capitol of the U.S.A. take things a little more seriously.

Just a little... 😜

Now that's an impressive ground system. 👍🏼


* Disclaimer: I am a HughesNet customer and not a HughesNet employee. All of my comments are my own and do not necessarily represent HughesNet in any way.
Assistant Professor

Re: Need to know IF frequency used between antenna and modem.

Nice, but more than the average customer is going to do. Was only keeping it real for the normal HughesNet customer. Extreme lightning protection is neither needed or cost effective for the majority of customers. I do have extensive experience with gounding and radio antenna towers. A dish 5 foot above the ground or even on a roof is not the same as as a 200 foot tall tower.  I'll bow out now.