in2connect Discuss The Role Of Broadcast Connectors

Bob Hart, Managing Director, In2Connect UK Ltd
Broadcast applications from the simplest hand held kit to a fully blown flyaway or OB vehicle have carried the world's best loved I/O connectors into a harsher and less tolerant environment. Broadcast connectors face numerous environmental stresses, whether on the end of a cable or built into head end transmission kit. They must match the level of product technology and the rapid development and growth of the sector and must combat temperature and humidity; exposure to liquids, oils and chemicals; shock or vibration and RF/EMI interference. Above all, whatever the specific application, they must provide absolute fail safe always “on-air” reliability.
Despite all the warnings to avoid the use of electronic devices in wet areas, broadcast equipment designers have to create devices that can cope with water and humidity as their kit may be flown any where across the globe. Traditionally, most electronic boxes have been located in a sheltered, controlled environment. In broadcast applications, waterproofing of components is arguably the first major add-on to the features required of an indoor interconnect and it has become very clear that many engineers and designers don't want to reinvent interconnects for the sake of it, they want manufacturers to adapt products that they've already got built into BOMs.
As a prime example of this, whilst the D-sub I/O connector is a very mature product it remains extremely popular across the industry and with the acceleration of OB kit build, the connector manufacturer has seen an accelerating demand for more robust D-sub designs both waterproof and filtered against RF or EMI.
Just how ‘sealed' is a sealed connector? EN 60529 is an international classification system for the sealing effectiveness of enclosures for electrical equipment against the intrusion of foreign bodies and moisture and was developed by the International Electrotechnical Commission. It isn't specific to connectors, but they form an integral part of entering or exiting most enclosures. This system utilizes the letters "IP" ("Ingress Protection") followed by two or three digits. The first digit indicates the degree that persons are protected against contact with moving parts and intrusion: 6 = No ingress of dust; and complete protection against electrical contact.
The second digit indicates the degree of protection of the equipment inside the enclosure against the harmful entry of various forms of moisture (e.g. dripping, spraying, submersion, etc.): 7 = No ingress of water in harmful quantity when immersed in water under defined conditions of pressure and time (up to 1 m of submersion), i.e. temporary immersion. 8 = Suitable for continuous immersion in water under conditions which shall be specified by the manufacturer but is usually taken to cover depths say between 1 and 3 metres. It doesn't cover the pressures associated with deep sea exploration, etc.
If one takes the ubiquitous D-sub connector, the aim has been to reduce the number of components that make up the connector, hence remove all possible leakage paths and manufacturers have generally produced an IP67 rated connector by adding a mounting plate with a silicone O-ring to create a watertight seal at the panel interface and back potting screw machined contacts to prevent water ingress through the connector body. These are now available in pretty much all of the standard d type configurations excepting crimp.
Cost of course is amongst the leading drivers, thus the design concept for I/O connectors will always be limited by it ~ so in order to save space and reduce equipment size the industry needs to get more and more signals, such as common signals, microwave signals, optical signals, high voltage signals, power signals into a single connector whilst maintaining circuit or signal separation. This has been achieved with the IP67 mixed layout d-sub.
IP68 tends to be an application-specific rating, so there is no universal set of tests. With cost in mind, In2Connect has developed the “Pintail” range of low cost, functional waterproof connectors rated IP68 for indoor/outdoor interconnect solutions. These multi-pin, threaded coupling connectors will provide IP68 integrity when mated or when fitted with a waterproof end cap.
* Cut-Away photo of Pintail connector
The connector bodies are moulded from glass filled nylon and are available in free plug, cable end receptacle and fixed jam nut receptacle formats, all with dust caps to suit. Plug and socket can have either male or female solder bucket contacts factory fitted to allow design flexibility and polarisation. They are light weight, corrosion resistant and RoHS compliant with additional improved product features over competitive products; such as ~ planform contact identification by raised numbering for easy identification of circuits to save time and money when soldering or repairing incoming cables. Contacts are solder cup and are an integral part of the insulator, so less piece parts or crimp contacts to lose and no need for expensive crimp tools. To simplify the field assembly process, the dual O ring sealing means that the integral backshell can be easily removed in two sections to allow accurate soldering of the incoming cable. The threaded bodies provide a quick and easy connection to reduce installation and service time and have inbuilt key/keyway orientation with good cable waterproofing and retention by virtue of a rear compression nut.
D-sub and circular multipin in/out connectors are relatively chunky with or without additional protection, but the transition of RJ45, USB, FireWire IEE 1394 and Optical Fibre to the broadcast environment has required the application of the type of reinforcement associated with MIL-C circular connectors. For real-time-Ethernet, the industry has gravitated toward an RJ45 connector type with a bayonet latching or screw threaded coupling mechanism. This robust design with IP67 rating ensures reliable protection and easy connection under harsh environmental conditions.
* Photo of OB version RJ45 connectors
Senceive Ltd is a company that has developed a range of wireless solutions and applications across several sectors. From rail embankment monitoring to mining tunnel condition monitoring, their systems are designed for infrastructure-free industrial environments. The Senceive solution uses a wireless mesh-networked, intelligent sensor system consisting of a collection of small devices, equipped with sensing, communication and computation capabilities.
* Photo of Pintail connector on Senceive Ltd Wireless Mesh Network
In summary, with proper design and careful component selection, the common connector formats for I/O connections can often be used in Broadcast applications. With careful evaluation of the specifications, design engineers can avoid expensive connector formats and utilize the cost savings of the various families of ruggedized commercial I/O connectors.
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