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Effect of Temperatures on SNR and Power Signal levels

Back in late March 2019 when I looked at my SNR and Power levels my SNR ranged from 39.7 to 40.9 dB.

Today they range from 37.4 to 38.8  dB.

Power levels were 9.1 dBmv to  12.9 dBmv.

Today they are 8.0 to 10.6 dBmv.

 

Between the NID and the Router coax cable connection is a splitter that is being used as a barrel connector basically. 

IT's a 1 to 2 splitter. Should I consider putting a terminator cap on that port 2 of the splitter?

Is that even possible?

My main question though has to do with snr and power levels and the effect of temperature. Lately for the past several weeks around here it's been 90+ . The before readings were taken when the temps were at least 20 degrees cooler. 

What is your experience ?

TIA

6 REPLIES 6
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Re: Effect of Temperatures on SNR and Power Signal levels

An open port is always a risk.
Replacing the splitter with a barrel coupler may be a bit risky though.... some modems get weird when downtream signal level crosses a 13db threshold.

Should look into terminating that unused port---but don't put the termination cap directly on it. You risk a weird reflection issue. There should be at least a foot or so buffer of cable length from each connector in a segmemt of RG6 cable to help mitigate it. That is why 3 foot cables are so common, even when you don't really need that much cable.

So yeah... get you about a 3 foot cable to put on that open port, and then put a termination cap at the other end. May find the signal improves just a smidge, especially if there was ingress through that open port.
Contributor

Re: Effect of Temperatures on SNR and Power Signal levels

ideal-av-connectors-85-073-4f_1000.jpgDon't do this.So basically I should get a 3 ft length of coax attach it the open port and then terminate the 3 ft length of coax? Just wanting to be sure I am interpreting what you said is correct.

 

At some point in the future, I'm going to pay Spectrum to run a single line from the NID to the Router junction. 

I have no idea why they didn't do that in the first place. 

 

would this suffice:

 

https://www.amazon.com/SATELLITE-Tri-Shield-Satellite-Cellular-Compression/dp/B07ML9ZVGH/ref=sr_1_7?...

 

So you think a terminated splitter would be better than this:

 

https://www.amazon.com/CIMPLE-CO-Extension-Connects-Connector/dp/B06XGX57SS/ref=pd_cp_328_2?pd_rd_w=...

Sharer

Re: Effect of Temperatures on SNR and Power Signal levels

Correct... about a 3 foot cable, then a termination cap on that unused port.

BUT... RG6 quadshield cable, not rg11.

Don't want to get into the weeds of comparisons between the two, but basically you may not really see real significant differences in usable signal quality between RG11 and quality RG6 Quad until you pass about the 150-175 foot continuous run... not to mention a substantial difference in cost. Also, with only a 3 foot piece of RG11, you may actually knacker up the SNR a little because of the higher reflection potential.

Using the coupling barrel could also be problematic as well. Taking the splitter out will increase downstream levels as much as 3 to 4db. With how high your levels are now, that risks overdriving the modem's inputs. The modem will automatically adjust on the upstream output level based on feedback from the headend, but there is no such communication/tweaking for the downstream side... which would require a couple service calls to rebalance things (first call to check local premises, then escalation to a higher tier... and depending on where they need to tweak, may need escalation again). And then there is the issue of breaking out an additional line(s) in the future... putting a splitter back in play would then drop signal and if it drops too low, you are back in the same service call loop again.
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Re: Effect of Temperatures on SNR and Power Signal levels

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Re: Effect of Temperatures on SNR and Power Signal levels

Sure... any decent rg6 quad shield cable at lest 2.5 feet will do. Seen 6ft and 3ft on the shelf for $5-12 in lots of places... hardware stores, Walmart, etc.

Just don't want a long cable that has to be coiled up (induction noise), and want quad shield with compression fittings (not crimp on or screwed on connectors). The termination cap just needs at least 2.3 foot distance from the splitter, and it needs to have good shielding/ground connections to "seal" the line from RF interferences.
Contributor

Re: Effect of Temperatures on SNR and Power Signal levels

when the Spectrum tech came out back in March 2019 he put new compressions fittings  at the nid to the  splitter in and splitter out .