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Bitácora Técnica de Tux&Cía., Santa Cruz de la Sierra, BO
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Monday, August 30, 2010

mi WiMax de Viva en Santa Cruz, Bo

Cansado ya de conexiones a medias (mal crimpado y soldado de los conectores) de los técnicos de WiMax en Santa Cruz de la Tierra Quemada, Multinación Cocalera de Bolivia, doy una sugerencia técnica para los cables coaxiales y sus conectores para la antena externa.
How to Connect Coaxial Cable Connectors
A cutaway view of a coaxial cable.
Coaxial cable is any cable that has an inner wire shielded an outer conductive sheath by a dielectric (non-conductive) material. The outer conductive sheath is then encased in a protective cover. First invented in 1929, and used commercially in 1941, today coaxial cable comes in hundreds of types and is used in thousands of applications. Originally created with copper, today coaxial cable may use a variety of internal metals. Most of us are familiar with how the coaxial cable is used to wire cable and televisions systems. In this wiki, we'll look at how to attach your own connectors to cable TV coaxial cable.
Asumo que por reducción de costos de Viva o por razones técnicas de los cables y el tipo de conector de la antena externa, usan dos tipos de cable para conectar la antena con el CPE ZyXel, que no son más de 8-9 m (Ver el texto resaltado en negrita y rojo abajo sobre el tipo de cable grueso y la distancia mayor a 60 m o unas 200 yardas). 
Tampoco usan cintas de caucho y tubos retractables bajo calor para hacer las conexiones estancas o resistentes a la intemperie para evitar la entrada de humedad o agua a los cables coaxiales.
Respecto a los cables coaxiales, usaron un cable grueso de 50 Ohms conectado con  el  delgado LMR 240 como latiguillo o pigtail super largo (5-6 m=un valor de 20-25 US$) para conectar al CPE.
La unión de ambos tipos de cable fue hecha
-asumo yo- con Neill conectores baratos o con conectores reversos TNC  que son weatherproof por diseño, pero si el crimpado fue mal hecho y  como sobresalía la malla que cubría el anillo de crimpar, pues dudo que sea estanco sin el tubo del plástico retractable al calor (Clamps with clamp gaskets, Crimps with heat-shrink tubing), pero la cubrieron de cinta aislante 3M y quedó por suerte bajo las tejas, pero a la aislación  del conector con la antena no le tengo mucha fe, por más cinta aislante que tenga. Veremos qué pasa tras unos meses de lluvia y sol.
RTNC -Moisture Resistance: MIL-STD-202, method 106
Si por lo menos hayan aprendido a crimpar los conectores como se debe! connectors howto
Amphenol TNC Developed in the late 1950's, the TNC stands for threaded Neill Concelman and is named after named after Paul Neill of Bell Labs and Amphenol engineer Carl Concelman. Designed as a threaded version of the BNC, the TNC series features screw threads for mating. TNC are miniature, threaded weatherproof units with a constant 50 Ω impedance and they operate from 0 - 11 GHz. There are two types of TNC connectors: Standard and Reverse Polarity. Reverse polarity is a keying system accomplished with a reverse interface, and ensures that reverse polarity interface connectors do not mate with standard interface connectors. Amphenol accomplishes this by inserting female contacts into plugs and male contacts into jacks. RG stands for "Registered Gauge" The numbers of the various versions of RG cable refer to the diameter and internal characteristics of the cable, including the amount of shielding and the cable's attenuation, which refers to how much signal loss there is per length of cable.
There is no meaning to the numbers used for different cables types; they are arbitrary labels assigned long ago.
Most non-industrial coaxial cable is now RG-6, although the previous thinner lower-quality standard of RG-59 is still used in some applications and older homes. Commercial installers may use a thicker RG cable, like RG-11 (which is only used if the distance from the source tap to your point of termination at the home is greater than 200 feet)
Be aware that all cables (and their connectors) come in a variety of qualities
Get the best quality cable you can.

TNC connector on the left beside BNC.

Reverse-polarity TNC (RP-TNC) is a variation of the TNC specification which reverses the polarity of the interface. This is usually achieved by incorporating the female contacts normally found in jacks into the plug, and the male contacts normally found in plugs into the jack. RP-TNC connectors are widely used by WiFi equipment manufacturers to comply with FCC regulations designed to prevent consumers from connecting antennas which exhibit too much DB gain and breach compliance. This connector is common on WiFi or Broadband Routers and Antennas from Cisco, Linksys and other lines of Wi-Fi products. RP-TNC can also be abbreviated as RPTNC.
Abajo el conector de polaridad reversa (RP-SMA) para el cable coaxial
LMR-240 y el ZyXel MAX-210M1 como un simple CPE acorde al estándar IEEE 802.16e (Ver WiMAX) y frecuencia de 3,5 GHz
female rpsma connector Back of Router RP-SMA Female Connection
Conector hembra de polaridad reversa del CPE ZyXel
rpsma male
Sub-Miniature version A
Reverse Polarity SMA Male Connector
Product Spec.
cómo hacer las conexiones
SMA connectors are semi-precision, subminiature devices that provide repeatable electrical performance from DC to 12.4 GHz with flexible cable. These devices offer broadband performance with low reflection and constant 50 ohm impedance. These properties, along with minimum attenuation and low VSWR have made the SMA extremely popular in the microwave community. The SMA design has been broadened to accommodate many interconnect requirements and is available in pressure crimp, clamp and solder terminal attachments. SMA design parameters have incorporated the considerations of balancing cost, size, weight and performance to yield the best value in your microwave system. Among typical applications are components such as dividers, mixers, amplifiers, trimmers and attenuators. SMA connectors are also used to provide interconnections from printed circuit board stripliness to coaxial cable.SMA is available both in Standard and Reverse Polarity. Reverse polarity is a keying system accomplished with a reverse interface, and ensures that reverse polarity interface connectors do not mate with standard interface connectors.
Reverse Polarity SMA
Impedance50 ohm
Frequency Range0 to 12 GHz
• for flexible cable→max operation frequency of cable per MIL-C-17(12.4GHz max)
RG178U→1.2+0.025 f GHz max(Straight)
1.2+0.03 f GHz max(Right Angle)
RG316U→1.15+0.02 f GHz max (Straight)
1.15+0.03 f GHz max (Right Angle)
RG142U→1.15+0.01 f GHz max (Straight)
1.15+0.02 f GHz max (Right Angle)
Working Voltage375 volts rms max
Dielectric Withstanding Voltage100 volts rms
Insertion Loss0.06 dB maximum x??GHz@ 6GHz;
Insulation Resistance5,000 Megohms min
Mechanical and Environmental:
Mating1/4"-36 threaded coupling
Durability500 matings
Coupling Nut Retention60 lbs Min
Cable RetentionRG-58,141,142,223→41 lbs min
RG-174,188,316→20lbs min
Thermal shock-65°C to 165°C
Materials / Finish:
Connector BodyBrassNickel or Gold
Center ContactMale:Brass
Female:Beryllium Copper
30 µ " gold over 100 µ " nickel
GasketSilicone RubberNone
Crimp FeruleAnnealed CopperSame as Body
Assemblies Instruction
Do not use the screw-on style F-type connectors. Cable signal will "leak" out of a cheap or poorly terminated connector such as these. This can cause unwanted signal "ingress" to get into the cable line and cause odd distortions such as vertical lines, dash lines moving horizontally across the screen as well as "beats" or little white dots randomly over the entire screen. If you have high speed internet and more than two TV's, make sure you use a high quality RG 6-type connector. On this note, when putting a connector on the cable wire, proper preparation is essential to get a clear picture as well as a good seated connection for the cable modem. Use a compression style connector available at any popular home improvement center. Also, when preparing the end of the wire, be sure not to "score" or nick the copper center conductor as this can cause problems with your internet such as intermittent connectivity and packet loss.

  • Professionals use compression fittings on coax with a compression tool that is not much more expensive than a crimper. These are used now instead of crimping as it makes a more waterproof seal, and affects the signal less at the joint point.
  • Make sure you make a good connector.
    Do not settle for a less than perfect job.
    Cable TV signal can leak out of bad connectors and interfere with lots of devices that use RF technology (including airplanes).
    Not to mention that if too much signal leaks out it can be an FCC violation.
    If you are unsure leave the job up to the professionals at your cable provider.
Bien, por eso escribo ésto, pues al proveedor de internet (ViVA) no parece importarle la calidad de sus conexiones. Y por eso paran sus técnicos atendiendo reclamos!!!

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