Duplex Repeater
Duplex Repeater :: Choices of connectors Over the years, a large variety of fiber optic connectors have been designed for most fiber optic installations. Lightwave equipment manufacturers have never...
Duplex Repeater
:: Choices of connectors
Over the years, a large variety of fiber optic connectors have been designed for most fiber optic installations. Lightwave equipment manufacturers have never standardized on any one connector type, they actually provide a selection of connectors for their equipment interface.
It is very important to choose the fiber connector type for your applications. You should maintain a connector standard throughout a fiber optic project.
:: The components of a fiber connector
For most fiber optic connectors, the major components are ferrule, connector body, connector cap and strain-relief boot.
Ferrule
The ferrule is the center part of the connector. It contains the optical fiber in a center hole. Ferrule can be made from ceramic (Zirconia), stainless steel or composite material.
Ceramic ferrule is the most popular material since it has stable temperature characteristics. The most common ceramic is Zirconia which is a white hard ceramic material. Ceramic ferrule is used for both single mode and multimode connectors. It offers the lowest insertion loss and the best repeatability.
Connector Body
Fiber optic connector body can be steel or plastic. The body design differs from connector to connector. The connector body provides the mechanism to hold the ferrule and other parts together. It also provides the locking mechanism for connector mating. The most common locking mechanisms are push-pull, snap-in, thread on and twist-on.
Connector Cap
Connector cap often has the same material as the body: either steel or plastic. The cap can be screw on, twist lock or snap-on for connector mating.
Strain-relief Boot
Strain-relief boot is the part connecting the connector body and the fiber cable. It is often made from rubber. Although it looks minimal, it is actually one of the most critical parts in a connector. It provides strain relief on the optical fiber to prevent micro-bending, breakage and provides mechanical support for fiber and connector handling.
:: Legacy Fiber Connector Types
The following list shows the legacy connector types that have been deployed in numerous fiber optic networks for many years.
ST Connector
ST connector was once the most popular fiber connector. It was well-liked for both single mode and multimode fiber connections. The average insertion loss for a ST connector is about 0.5dB.
ST connector has a twist-on locking mechanism which is not susceptible to loosening in vibrating environment. It is most often used in LAN networks.
FC Connector
FC connector is popular for single mode applications. It has the lowest insertion loss and the best repeatability. It has a thread-on locking mechanism.
SMA connector
SMA connector is a pretty old connector type which is mostly used for multimode applications. Today it is still being using on medical equipment.
There are two types of SMA connectors on the market: SMA 905 and SMA 906. The only difference between them is that SMA 906 has a straight ferrule while SMA 905 has a step-down ferrule.
D4 Connector
The NEC D4 was probably the first connector to use ceramic or hybrid ceramic/stainless steel ferrules. It uses a smaller ferrule than SCs or FCs. It was widely used in telco networks in the 80s to early 90s and some may still be in use.
FDDI connector
Besides the SC Duplex, you may occasionally see the FDDI duplex connectors which mate to their specific networks. They are generally used to connect to the equipment from a wall outlet, but the rest of the network will have ST or SC connectors. Since they both use 2.5 mm ferrules, they can be mated to SC or ST connectors with adapters.
Biconic Connector
Biconic connector’s yellow body indicating a SM version – mutlimode versions were usually black. Biconic connector was developed by a team led by Jack Cook at Bell Labs in Murray Hill, NJ.
About the Author:
Colin Yao is an expert on fiber optic networking technologies and products. Learn more about
bulk single mode fiber
,
corning fiber optic cable
,
outdoor single mode fiber
on Fiber Optics For Sale Co. web site.
Article Source: ArticlesBase.com – The Story Of Legacy Fiber Optic Connectors
|
|
Motorola Repeater with Duplexer $1,350.00 |
|
|
GE VHF MASTER III REPEATER WITH TX/RX HIGH END DUPLEXER $1,799.00 |
|
|
VHF 35W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING AU3 $80.95 |
|
|
UHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING AU3 $90.03 |
|
|
UHF 35W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING AU3 $80.95 |
|
|
VHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING AU3 $90.03 |
|
|
6 cavity duplexer for radio repeater UHF FREE tune $79.99 |
|
|
6 cavity duplexer for radio repeater UHF FREE tune $79.99 |
|
|
6 cavity duplexer for radio repeater UHF FREE tune $79.99 |
|
|
VHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING CA1 $83.43 |
|
|
VHF 35W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING CA1 $74.99 |
|
|
VHF 35W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING US3 $74.80 |
|
|
UHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING US3 $83.20 |
|
|
UHF 35W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING US3 $74.80 |
|
|
UHF 35W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING CA1 $74.99 |
|
|
UHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING CA1 $83.43 |
|
|
VHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING US3 $83.20 |
|
|
UHF 6 cavity duplexer for radio repeater + FREE tune $79.99 |
|
|
UHF 6 cavity duplexer for radio repeater + FREE tune $79.99 |
|
|
UHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING AU2 $89.92 |
|
|
6 cavity duplexer for radio repeater UHF FREE tune $79.99 |
|
|
6 cavity duplexer for radio repeater UHF FREE tune $79.99 |
|
|
6 cavity duplexer for radio repeater UHF FREE tune $79.99 |
|
|
6 cavity duplexer for radio repeater UHF FREE tune $79.99 |
|
|
VHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING AU2 $89.92 |
|
|
UHF 35W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING AU2 $80.84 |
|
|
UHF 6 cavity duplexer for radio repeater + FREE tune $98.00 |
|
|
VHF 35W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING CA3 $75.19 |
|
|
UHF 35W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING CA3 $75.19 |
|
|
UHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING CA3 $83.63 |
|
|
VHF 35W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING AU2 $80.84 |
|
|
UHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING US2 $83.10 |
|
|
UHF 35W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING US2 $74.70 |
|
|
VHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING US2 $83.10 |
|
|
ICOM FR4000 UHF REPEATER 50 WATT 450-470 MHZ WITH DUPLEXER AND 19″ RACK MOUNT $1,350.00 |
|
|
Motorola Quantar VHF 110 Watt Repeater W Duplexer MRTI HAM $3,200.00 |
|
|
VHF 50W 6 CAVITY DUPLEXER FOR REPEATER -FREE TUNING CA3 $83.63 |
RNA interference (RNAi) or double-stranded RNA (dsRNA) is a system within living cells that help control which genes are active and how active are. siRNAs were first discovered by David Baulcombe's group in Norwich, England, as part of post-transcriptional gene silencing (PTGS) in plants1 and subsequently independently identified in a wide variety of eukaryotic organisms. These dsRNAs are rapidly processed into short RNA duplexes of 21 to 28 nucleotides in length, which guide the recognition and ultimately, the breakup of complementary single-stranded RNA as messenger RNA or viral genomic RNA, antigenomic / (Fig. 1). According with its origin or function naturally small RNAs have been described: short interfering RNAs (siRNAs), repeat associated short interfering RNAs (rasiRNA or shRNA) and microRNA (miRNA). RNA interference has many biological functions – is a vital part of the immune response against the virus and also downregulates gene expression through the silencing transcriptional or upregulates genes promoting activation of RNA. Finally, the artificial introduction of long dsRNA or siRNA has been adopted as a tool for inactivation of gene expression in both cultured cells and in living organisms.
A biochemical understanding of the RNAi pathway is crucial to realize that dsRNAs less than 30 base pairs (bp) could be used to trigger an RNAi response in mammals. Tuschl and colleagues showed that transfection mammalian cells with short RNA can induce sequence-specific RNAi pathway, by beating the barrier to the use of RNAi as a tool mammals2 genetics. The impetus for using siRNAs and other small RNAs in mammalian cells also came from the long view that protein kinase receptor (PKR) activation3 and similar responses were not actually caused by short dsRNAs. After initial reports, it took a remarkably short period of time Triggers for siRNAs to be adopted as a standard component of the toolbox of molecular biology. siRNA can be introduced into mammalian cells using a variety of standard transfection methods. The strength and duration of the silencing response is determined by several factors: a population basis, the silencing response is affected mainly by the overall efficiency of transfection, which can be addressed by optimizing the conditions. In each cell, the silencing depends on the amount of siRNA that is delivered and the potential of each siRNA to suppress its target, or its power. Even a relatively powerless siRNA can silence its target provided that sufficient amounts of siRNA delivery. However, essentially "forcing" the system by supplying large quantities of reagent can give rise to many undesirable effects.
About the Author:
url: www.biosyn.com
site_owner: Jessica Castro
address: 612 E. Main street
city: Lewiville
state: Texas
country: USA
postal_code: 75057
phone_number: 972-420-8505
Article Source: ArticlesBase.com – RNA Interference (RNAi)