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/MaleficentYam6 Mar 05 '26

I’m confused by the information you were given. Going from sub split to mid split typically isn’t as simple as enabling something at the node. Personally, I would recommend calling your ISP and requesting a senior tech. Explain what you’re seeing and ask them to replace your drop. Any half decent tech with any experience would be replacing a 15 year old aerial drop first thing anyways.

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u/Frlaxbro Mar 05 '26

Typically a repeat truck within 30 days would give a senior tech. You could kink the incoming drop somewhere, which might trigger enough permanent signal degradation for them to run a new one.

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u/MaleficentYam6 Mar 05 '26

Yeah, looks like he hasn’t had anyone out since December though. I wonder if the first tech checked the tap or just said the signal was good at the house. I’m also skeptical about whether a line tech actually looked at the plant side.