halfband
Premium
join:2002-06-01
Huntsville, AL
| surge suppressors for cable modems
This got started on another thread here »Approved Comcast Modems Modem List
by Talking Points Memo and Pmokover.
What are good surge suppressors and should they be used at all?
APC makes one:
»www.apcc.com/resource/include/te···yCode=US
and TrippLite
»www.tripplite.com/products/produ···ctID=156
This looks promising:
»www.comm-omni.com/angel/gacoaxgb.htm
Found in this thread
»Advised by Comcast not to use surge protector
I don't know how good these are. A really good one is hard to find and often looks just like a poorly designed one.
All you Comcast techs out there, which brands of surge protectors do you like? Which cause you the least problems (low loss and ingress) but seem to work well.
Anyone have any experience with a protector model that has worked when taking the big hit? |
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pmokover
join:2001-12-02
Ventnor City, NJ | I'm using one (actually two) designed for commercial communications systems. I'll try to find the manufacturer and post it here.
I also have surge suppressors on all of the phone lines coming into my house. |
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rody_40
join:2002-04-14
Quakertown, PA
| reply to halfband
as a tech i hate surge protectors. my opinion is just unplug the modem when it is storming. as i have seen lots and really havent seen any worth the problems they develop. sure i know there are some good ones i just havent seen them. i have never went into a subs home that uses them that dont have more problems than people that dont. |
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systems2000
What? You Say It's Fixed. Hah
join:2001-11-29
Cyberspace | reply to halfband
Try this »www.apcc.com/products/family/index.cfm?id=28 |
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TelcoCable_X
Q1 4 Ever
join:2002-02-10
Long Valley, NJ | reply to halfband
Home depot has a Belkin model with a cable line surge protector on it. I bought it but then returned it because it didn't have an "unswitched" outlet like my current model does.  |
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beerbum
Premium
join:2000-05-06
Reading, PA
clubs:
| reply to halfband
said by halfband:
This looks promising:
»www.comm-omni.com/angel/gacoaxgb.htm
with a return Loss >-24dB as stated on that web page, you can kiss any chance of a cable modem working through that. those other two by APC and Tripplite are nothing but overpriced and glorified ground blocks, which BTW should be installed and properly bonded on any property that has any type of CATV service.
quote:
What are good surge suppressors and should they be used at all?
the only good is a perceived sense of security. all but the most expensive surge protectors have one common flaw, they can fail, losing the ability to block any spikes all the while giving no indication the protection is no longer working.
those cheap surge strips with coax connections.. heh, you may get lucky and it works fine with the cable modem.. wait awhile, it will fail. |
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halfband
Premium
join:2002-06-01
Huntsville, AL
| Thanks for pointing out the 24dB loss. I had read it as 2.4dB, big difference. The area I live in has frequent storms. Lightning strikes are just part of the game here. I have had trees and the local power lines take a hit. It is just a matter of time until the cable lines take one. |
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systems2000
What? You Say It's Fixed. Hah
join:2001-11-29
Cyberspace
 ·Embarq
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Be sure you protect all copper lines to the outside World. Lightning, surges, and flaky power source can make it to your equipment on any connection that is made by copper (ie. Telco, Power, Cable, Satellite, etc.).
(EDIT): Forgot to mention that you can also have surges from PC to PC or equipment to equipment.
[text was edited by author 2002-09-11 22:40:38] |
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ZipperSeven8
join:2002-10-10
Tallahassee, FL
| reply to halfband
I work in retail, and have had a chance to see all the surge protectors that are sold and that are returned. We carry APC and Belkin, several models of which have coax outlets. After getting a bunch of returned Belkins, I investigated only to find that Belkin doesnt certify (their exact word) their coax surge protection for data. A lot of customers complained that hooking their TV's up to them even made static and lines appear in the signal , trashing our already crappy cable reception here. The APC's seem to fare a little bit better, but barely. We carry a model that says 'Designed for Cable Modems/DSL', but seem to be much the same thing as the Belkins: poorly designed for even video signals, let alone data. I wouldnt recommend these surge protectors to anyone, and have yet to find a coax protector that I have heard anything good about. For now: just unplug if the weather gets bad. |
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Tabasco Joe
@motorola.com | reply to halfband
That's not through loss, that's return loss. The "higher" the number the better it is. Most cable amps are only -16 to -18 dB return loss on their ports. |
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redsky58
We're All Mad Here.
join:2002-08-30
Plymouth, MI
| reply to halfband
I use an APC model PRO8TV. This power strip has coax and telephone as well as their $70k equipment guarantee. I have an APC UPS so it made sense to be consistent, especially since that is a requirement of the warranty.
It only introduces maybe 1.5-2 dB of loss. To me it's worth it for the protection I'm getting. |
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beerbum
Premium
join:2000-05-06
Reading, PA
clubs:
| reply to Tabasco Joe
said by Tabasco Joe:
That's not through loss, that's return loss. The "higher" the number the better it is. Most cable amps are only -16 to -18 dB return loss on their ports.
huh?
what kind of cable system are you talking about? certainly none I am familiar with. for return loss LOWER is better. do the math
24db loss on the surge device
4db loss on the splitter
14db loss at the tap (avg figure - taps can be 4-29db loss)
15db loss at the line extender amp
right there you have 57db of loss, and we're not even including the loss from the coax and a possible trunk amp.
you should know modems max working transmit is 58db shit that one surge device alone kills almost half the needed return signal.
only a fool would use one.
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Tabasco Joe
@motorola.com
| reply to halfband
The loss is not 24 dB. It has a return loss of -24dB. The specification on the third link says -24 dB return loss 0.1 dB insertion loss.
Return loss is the measure of reflected power from the port under test. The less reflected power the better the "match" to 75 ohms. If the amount of power that is reflected is too high it will cause flatness problems and at very high levels you could see ghost images in the picture. -24 dB is a very good match for a cable device.
The surge technologies used in the mentioned devices are not unlike surge devices we design into many pieces of cable equipment. There are several types and all can be destroyed with a large surge. If designed correctly they will help protect your equipment. I know first hand since we test all our designs to 2000 volt surges. Yes they can cause problems once they take a hit. If you have aerial wiring and live in a high lightning area they can save your equipment. |
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Tabasco Joe
@motorola.com | reply to halfband
By the way, I can understand that for someone not used to the terminology that they could mistake "return loss" as loss in the return band. The term return loss has a completely different meaning as described above. |
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halfband
Premium
join:2002-06-01
Huntsville, AL
| Thanks for the comments guys!
I think this is a pretty good definition of return loss.
»www.its.bldrdoc.gov/fs-1037/dir-···4597.htm
Here’s a another data sheet on the same item.
»www.comm-omni.com/tii/tiicoaxgb.htm
If you ignore the spelling errors, it does say it is for use with “internet cable modems” and “is virtually transparent to all analog or digital bi-directional signals transmitted from DC to 1.5 GHz.”
Here is the link for the main product page
»www.comm-omni.com/
The item above was listed under the Other Coaxial Protection section |
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jmich
Premium
join:2001-08-28
Toms River, NJ
clubs: | reply to halfband
I have used a Radio Shack Cable Modem Protector with 2dB loss according to the SB4100's s/s page. It comes with a 3 ft ground lead you can bond to a ground. It was like 30 bucks. Never had a problem w/ it. |
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mglunt
join:2001-09-10
Fredericksburg, VA
 ·Verizon FIOS
| reply to ZipperSeven8
ZipperSeven
I don't have any problems with the cable input on my Belkin surge protector. I don't run my cable modem line through it, but I do use them for my Coax connection coming from my DTV dish to the receiver. I used to use it for the regular cable TV without any problems or noticeable signal degredation.
A Belkin Surge protector I had took a surge once saving the PC. I called up Belkin, and they replaced it free of charge. The unit was about 3 yrs old, so the new one was alot better. |
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jimeez
Heads Are Empty
Premium
join:2002-04-28
Mount Holly Springs, PA
clubs: | reply to halfband
Here you go, all. Take a look at this.
http://www.leviton.com/pdfs/surge/51110-PTCprodbulletin.pdf |
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