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Craft issues in coax can create havoc later on…

Happy Friday Everyone. Today is September 20th and this is episode 51 of Get Your Tech On, our show on All Things DOCSIS. I’m Brady Volpe, Founder of The Volpe Firm and Nimble This. With us is, John Downey, who will strike a pose at this years SCTE EXPO. John is also CMTS Technical Leader at Cisco Systems, welcome John. Also with us is Rich Maroney Product Line Manager Coaxial Cable from PPC.

Today we are going to discuss the importance of proper connector termination with DOCSIS cable connector basics.

But First
A Shout out to North Country SCTE where I gave a DOCSIS 3.1 Remote-PHY Technical Presentation last week.

In The News

Check out my article on 

https://volpefirm.com/high-latency/

Todays show overview:

  • Latency / Jitter
  • PNM identifies poor performing cable modems
    • often times it’s poor connectors
    • micro reflections
    • step one have good tools not crimp connectors
    • have good prep tools / sharp blades
    • good compression tools that are not worn out
    • poor connections wreck havoc in the field

  • DOCSIS Cable Connector Basic – Issues Ranked

  • Number one craft issue not properly tightened on the port
      • Not to tight not to lose
      • Set top box or modem – finger tight
      • Wall plate or out on line / field – torque wrench
  • Number two too long of a center conductor / Prep side
    • Prep tool without stopper
    • Too long of a center conductor can bottom out and flare the center conductor and permanently flare open the contacts. causing a gap
  • Common measurements 0.25, 0.25, 0.25 inch
    • dielectric of series 59, 6 or 11 cable and similar to mini coax
    • initial prep important 
    • Prep vs razor blades / fixed blade use sharp blade
  • Sheath currents or skin effect
    • Past the copper
    • scoring the copper
    • higher frequency run closer to the edge of the cable on the outside of the copper so when you damage it you are causing yourself issues later on.
    • This is a trouble call
    • Or a PNM yellow or red modem
  • Mini Coax – sensitive like fiber
  • Pay attention to craft of cable work
  • Number three braid removal
      • Dull blade will wrap it around the center conductor
      • Shorting out signal when this happens
      • The aluminum foil is bonded a bit better in the US than in some countries, so milage may vary
      • Braid cut
      • Braid sticking out past connector can let water go in and ingress and corrosion
        • first prep – braid is going staring up to dielectric
  • Number four proper compression
      • good seal from moisture stand point
      • good retention
      • lever action
      • correct compression length
  • Extended spectrum DOCSIS going to higher frequencies
    • 3 GHz connector’s 
    • Good connector, great cable, great craft = solid DOCSIS signal
  • Cable RG11 bigger coax?
    • green field
    • 1.2 Gig
  • Number five messenger cable
    • zipper formation
    • worse case bad jacket older cable UV damage
    • down and towards / wrap back
    • do not stretch cable / do not rip
  • Number six dielectric damage
    • pushed to far thru
    • recessed to far
    • the foam is pinched
    • center it up or taper
    • bad prep tool
    • Best way to remove foam with finger nail or plastic credit card / no metal to remove it
    • A little bit of glue can act as a 6 dB pad – lower frequency 
  • Drip loop / ground block
    • drop clamp
    • Hum mod
  • Number seven weather seal – complaints and value
    • Lab tests indoor and outdoor  
    • Moisture ingress arial or buried 
    • Splice in a drop last?
  • Number eight short center conductor – will not make conduct
    • F connector 
    • drop cable
  • Hardline cable QR / jacket error heat shrink / prep tools / good core tool
  • Smashing pin
  • Node plus zero power feeder 625 cable – solid center conductor
  • Be careful with power tools

John and Rich thank you for your time today. This was a great episode. Our next Episode 52 is scheduled in October 8th on SCTE EXPO Recap.

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