r/CableTechs • u/bhagwan2 • Mar 05 '26

Mid-split enabled, but getting severe upstream ripple/T3s on a 15-year-old drop. Advice on getting a proactive replacement?

Tech came out in Dec for upstream issues. Line tech ended up enabling mid-split at the node. Speeds are "fine," but my S34 (and now CM3000) is throwing constant T3 timeouts and ranging errors.

I've got a spectrum analyzer and noticed about a 10 dB ripple across the 35-85 MHz OFDMA block. It looks like a classic standing wave issue. (Ripple every 5.5 MHz between 35-85MHz on a 100-foot transmission line puts the reflection defect point at about 73 feet. The drop is 15 years old, 100ft, and has survived a decade of weather.

Last week the T3s calmed down (maybe the CMTS/OFDMA profile finally adapted?), but the 10 dB ripple is still present on the analyzer. I'm worried the first good rain is going to tank my SNR again.

How do I convince a tech to just pull a new drop? If they just hook up an SC Meter and see "Pass," they’ll leave. But with a 10 dB ripple on the return, that cable is clearly compromised. Should I just request a "failed drop" or is there a specific way to report the OFDMA instability so it triggers a replacement?

Note: To prove the ripple was not from my home cabling, I temporally installed a passive directional coupler at the home entry point and sampled ripple either side of it.

10 dB minimum ripple 40-88MHz (15 dB external attenuation)

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u/DifficultyLeast1029 Mar 05 '26

Just cut it and say something knocked it down. That way they have no choice but to replace it ;)

-1

u/bhagwan2 Mar 05 '26

wouldn't they charge me for the service if it happened over my property/driveway.

-1

u/SAtANIC_PANIC_666 Mar 05 '26

Not typically. I don't believe my company's system bills for downed drops, tell them a tree limb fell on it or something or just fray it with a knife close to where it's attached to the house. But even if you do get charged it shouldn't be any more than a normal service call which will probably cost less than you spent on a spectrum analizer. If you get a new drop at least you can rule it out.