Telco vs. cable networks: connectors

Ray Minich · Post by **Ray Minich** » 6 Jan 2006 8:53 am

"Actually, the HFC network operated by CATV service providers is superb until the signal gets to the home and the F connector. The technical downside to the F connector is that the cable-center conductor was not engineered to withstand the environment outside the cable dielectric, so it corrodes very quickly. The business reality is that 65% of CATV customer service ¡°truck rolls¡± are directly attributable to failure of these pinless F-connectors. The lowly F-connector can provide a troublesome, unreliable and, from a maintenance perspective, costly RF interface, and still is the cause of most drop-related service calls.1
The coaxial connector specification in the CATV sector contains little evidence of engineering rigor. Clearly, the weak link for the high-bandwidth carrier-class assignment in the CATV hybrid fiber/coax network is the pinless F-connector. The performance limitation of the pinless F-connector is technical.

For example, the center conductor of the cable that acts as a mating pin is vulnerable over time to fretting and oxygen-related corrosion when exposed to air and encapsulated in the mating socket. Also, installers routinely fail to tighten the threaded coupling sleeve on the plug to the proper specification (1/4 turn with a wrench after finger tightening). Furthermore, the value of return loss over elevated frequency (2.2 GHz) is marginal, particularly compared to the carrier-class connector for 75-ohm coax in the public network. Finally, the socket in the jack must accommodate too wide a range of wire centers as contacts. "

Great article about BNC vs F connectors and DSL vs Cable. See the following... http://cs.pennnet.com/Articles/Article_Display.cfm?Section=ARTCL&ARTICLE_ID=243912&VERSION_NUM=2&p=42 [This message was edited by Ray Minich on 06 January 2006 at 09:06 AM.]

Donny Hinson · Post by **Donny Hinson** » 10 Jan 2006 3:50 pm

Being a professional trouble-shooterconsultant, I have to agree. Every "cable guy" should carry a tube of clear silicone grease, and he should use it on every screw-on connector, both on the threads and the center conductor. Nonetheless, I've yet to see any cable guy use any corrosion preventative! You'd think that people in the business and doing that stuff for a living would have some proper proper training, or at least some degree of common sense.

Evidently not.

I just call the every year or so, and have them re-cable or re-terminate everything so it works good.

John Bresler R.I.P. · Post by **John Bresler R.I.P.** » 10 Jan 2006 4:04 pm

I think it's kind of interesting that Sony, GE and others have flooded the market with cordless home phones that don't work when the AC power goes out. Everyone should have an old Western Electric AT&T phone to plug in when the AC fails in case of emergency.

I'm retired from the Telecommunications Industry and remember that it is true that Telco cable splicers always used a silicon gel on the splice ends to prevent corrosion. Good article.

Jack Stoner · Post by **Jack Stoner** » 11 Jan 2006 3:40 am

To add, there are many "POTS" phones around that do not need AC power. You don't need the obsolete and defunct "Western Electric" phones. The AT&T monopoly went out years ago and the telecommunications have advanced beyond "Ma Bell" being the only provider of telphone equipment.

When I first got into (non-military) data communications, I had racks of "WECO 829's" (channel interface units), when I retired in 1996 I din't have any AT&T or WECO equipment and all my circuits (both analog and digital) were still "AT&T" circuits. All the AT&T supplied equipment was made by other companies.