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MB8600 modem signals, good/bad?

herrnf
Frequent Visitor

MB8600 modem signals, good/bad?

Hello everyone,

 

I just got Comcast, and they ran a new line from the street underground to the junction box on the outside of my house. They installed a splitter, and I asked him wouldn't it be better if there wasn't one, to which the tech replied stating that the power is too strong coming from the street, and in fact I might need to add another before connecting to the modem.

 

I accessed my modem (MB8600) and got the following results.  Do I need to add another splitter before connecting it to the modem? Any recommendations on make/model to use for splitter for this?


Thank you in advanced to any who comment and help me.

 

PS - I can't figure out how to copy paste everything here like I've seen other's do, without it being very difficult to read. Here is a link to the image of the results.

 

https://ibb.co/7YyRr2Z

 

CCAndrew
Diamond Problem Solver

Re: MB8600 modem signals, good/bad?

Everything is basically in spec, another splitter will push your upstream too high and out of spec.

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herrnf
Frequent Visitor

Re: MB8600 modem signals, good/bad?

Thank you for your response @CCAndrew.  I have an update and some follow up questions if you do not mind. I appreciate you taking the time.

 

I forgot that I had a Commscope CSMAPDU9VPI in the closet, so I pulled it out to test. I didn't use AC power on it, I simply connected the coaxial from the side of the house, to the input, and then used the 'VoIP Out -6dB' and plugged that into the modem. 

 

I got the following readings here:  https://ibb.co/frgTDkH

 

The dBmV seems to have gone down that -6dB as specified on the amplifier, so that is good. My assumption is that closer to 0 is the goal?

 

I did not realize that a splitter would increase Upstream, as you indicated. It would appear that the Upstream dBmV did indeed go up more. I have removed the CSMAPDU9VPI as such.

 

Is there a way to only decrease the Downstream (since its borderline), while not increasing the Upstream?

 

Here is a photo of the equipment located within the Comcast outdoor box on the side of my house. The technician installed the Commscope SV-4G you see there. Should that be replaced for someone more preferred? Is there such a thing as 'one-way' with regard to splitters? To decrease only the downstream and not increase upstream? I would imagine the SV-4G is also making the upstream go up as well?

 

https://ibb.co/0JMvjJ4

 

I want to ensure that my connection is as stable and as good as it can be, so I'm willing to do whatever I need to do accomplish this, especially since I'm working from home full time now.

 

Final question, what is the Corrected/Uncorrected columns about? Should I be worried? Is there anything I can do to lower those numbers? From this guide here, looks like I want them to be 0 ?

 

https://pickmymodem.com/signal-levels-docsis-3-03-1-cable-modem/

 

Thank you again !

 

EG
Expert

Re: MB8600 modem signals, good/bad?


@herrnf wrote:

 

Is there a way to only decrease the Downstream (since its borderline), while not increasing the Upstream?


A forward path only attenuator will decrease the downstream power and not affect the upstream power;

 

https://www.amazon.com/line-Signal-Forward-Attenuator-FPA6-54/dp/B07882H96R

 

 



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herrnf
Frequent Visitor

Re: MB8600 modem signals, good/bad?

Thank you for your reply @EG 

 

So I removed the splitter that Comcast tech installed (-7db) so now you can see my Downstream power levels are too high (average of 16dBmV).

 

Results here:  https://ibb.co/ypP0x1y

 

My Upstream power level's appear to be perfect now, so now I just need to find a Forward Path Attenuator that is either already at 16dB, or can I connect a couple back-to-back?

 

I found this, but I cannot seem to find anywhere to actually purchase it.

https://www.commscope.com/product-type/splitters-combiners-multiplexers/coaxial-passives/coaxial-att...

 

 

EG
Expert

Re: MB8600 modem signals, good/bad?

Yes. You can cascade them. You could also try searching on e-Bay. I've purchased 10 and 15 dB FPA's there before. Good luck !



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herrnf
Frequent Visitor

Re: MB8600 modem signals, good/bad?

I was able to find a distributor for the Commscope product, so I am waiting to see if they can provide. Otherwise I will have to cascade two 7dB ones I found on Amazon

 

Thanks again!

EG
Expert

Re: MB8600 modem signals, good/bad?

Quite welcome !



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herrnf
Frequent Visitor

Re: MB8600 modem signals, good/bad?

Oh shoot....is that 16dB Commscope a 'Forward Path Attenuator' or just a normal in-line one that would increase my Upstream if used?

EG
Expert

Re: MB8600 modem signals, good/bad?

It appears to be a regular overall attenuator, not an FPA only.



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herrnf
Frequent Visitor

Re: MB8600 modem signals, good/bad?

Well there goes that ! 

 

Oh well, I guess daisy-chaning the two 7dB ones I found on Amazon will have to do. 

herrnf
Frequent Visitor

Re: MB8600 modem signals, good/bad?

Final question for you @EG 

 

For the two Forward Path Attenuators I am about to install, does placement matter?

 

I have a grounding block, should it go before that or after, daisy-chained etc. Or place one at the back of the modem too?

 

Just want to make sure I'm installing them at the right locations.


Thanks !

EG
Expert

Re: MB8600 modem signals, good/bad?

Right at the back of the modem is the preferred place.



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herrnf
Frequent Visitor

Re: MB8600 modem signals, good/bad?

@EG so I just installed the two 7dB forward path attenuators and umm....yeah that didn't work lol.

 

I plugged them daisy chained directly into the back of the modem. 

 

See my results here: https://ibb.co/dGY8sW1

 

Yes the Downstream went down 14dB like I wanted, but the Upstream also went up 14dB, which is what i don't want.  They are essentially acting like a splitter.

 

Did I purchase a faulty item?

 

This is what I bought here:  https://www.amazon.com/gp/product/B08DMBDJ1Z/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

Do you have any ideas on what I did wrong? Any recommendations?

EG
Expert

Re: MB8600 modem signals, good/bad?

That's not supposed to be. That is exactly what an overall attenuator would do. It doesn't appear that you did anything wrong. It seems that the description of it on the Amazon site is incorrect even though it says that it is an FPA. Or they sent you the wrong item.

 

Try e-Bay. I've gotten lucky there.



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herrnf
Frequent Visitor

Re: MB8600 modem signals, good/bad?

@EG  I have good news to report. After purchasing two overpriced 6dB forward path attenuators on eBay since it was the only option available at the time, and connected them back to back on the modem, my specs appear to be perfect.


Let me know if you think there is anything else i can do

 

https://ibb.co/34RcCGr

EG
Expert

Re: MB8600 modem signals, good/bad?

Looks golden !! Happy surfing !



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