MilesTek 1553 Blog

Custom Military Cable Assemblies – Trusted Quality

mguidry — Tue, 18 Aug 2009 20:01:35 +0000

Trusting MilesTek to be your provider for Military-Grade cabling requirements and components can easily be justified by the trust placed in us by our vendors and manufacturers. MilesTek is an approved supplier for many Tier I and Tier II Defense and Aerospace companies, including: Boeing, Lockheed Martin, Raytheon, Rockwell Collins, Honeywell, and L3 Communications. MilesTek demands excellence in components from trusted manufacturers such as: Trompeter Electronics, Raychem, Amphenol, Sabritec, MilesTek, Glenair, Amp, ITT and Radiall. Spanning high-volume production, to lower-volume custom work, you can count on MilesTek for high-quality products, first-rate service, exceptionally short lead times and on-time delivery. Our in-house design and engineering staff has the experience to custom design your cables, improve your current designs to optimize cost effective manufacturing, or build according to your prints. We are staffed by highly-skilled technicians dedicated to manufacturing quality products and delivering them on-time to meet your deadlines.

No wonder MilesTek is the recipient of the Silver Boeing Performance Excellence Award in 2008.

MilesTek advantages include:
• Large connector and cable inventory
• D38999 Circular Connector assemblies
• CAD Design Capability
• Detailed Drawing Proofs
• Same-day shipment of in-stock items
• Prototype Development
• Testing
• Build to Print
• ISO 9001:2000 Certified

Common cable assembly types:
• Coaxial
• Twinaxial
• Triaxial
• 1553-B
• Serial
• SCSI
• D38999
• Multi-Conductor
• Fiber Optic

Why Buy Trompeter Products From MilesTek?

mguidry — Thu, 09 Jul 2009 21:16:35 +0000

In 2009, Trompeter Electronics appointed MilesTek as an authorized distributor. With more than three decades of Trompeter experience, MilesTek’s expertise is unequal to any other distributor. The service provided by MilesTek is a compelling reason why customers should choose MilesTek for their Trompeter requirements. The key attributes are because MilesTek

Possesses a Large Trompeter Inventory
Ships Stock Orders Same Day
Has an Uncommon Ability to Serve
Maintains High Technical Competence

The legacy relationship of MilesTek and Trompeter Electronics dates back to 1975. First as a stock representative and moving on assembling products with Trompeter products for 20 years. These years of experience make MilesTek the pre-eminent expert on servicing the Trompeter product line.

To view the complete offering of Trompeter products, visit http://www.milestek1553.com/trompeter.asp

What is the legacy of the MIL-STD-1553?

admin — Wed, 10 Jun 2009 13:26:11 +0000

The digital data bus MIL-STD-1553 was published in 1973 to replace analog point-to-point wire bundles between electronic instrumentation. Revision A to the standard was issued in 1975 as a tri-service standard. After two years effort by a SAE task group, Revision B was published as a tri-service/NATO standard in 1978. Various notices have been published to update the standard. After 30 years of familiarity and reliable products, the data bus continues to be the most popular militarized network.

What are the Physical Characteristics of MIL-STD-1553B?

admin — Wed, 10 Jun 2009 13:25:17 +0000

The MIL-STD-1553B bus has four main elements: (1) a bus controller that manages the information flow; (2) remote terminals that interface one or more simple subsystems to the data bus and respond to commands from the bus controller; (3) the bus monitor that is used for data bus testing; and (4) data bus components (bus couplers, cabling, terminators and connectors). Data is sequentially transmitted and received in a multiplexing scheme over two copper wires from computer to computer at a rate of 1 megabit per second. In most vehicle applications, redundant buses are employed.

What are the Integral Hardware Pieces of a Typical Data Bus?

admin — Wed, 10 Jun 2009 13:24:23 +0000

The data bus LAN topology encompasses:

• Bus couplers (coupling transformers with fault-isolation resistors)
• Bus terminators
• Twinax cable (shielded twisted pair)
• Concentric twinax connectors (with a center contact and an
intermediate cylindrical contact)

Are Bus Couplers Necessary?

admin — Wed, 10 Jun 2009 13:23:21 +0000

If a terminal device has internal isolation resistors and transformers, then direct coupling is possible to the bus cabling without the use of bus couplers. Direct coupling connections must only be used with stub lengths of less than 1 foot. However, MIL-STD-1553B cautions the employment of direct coupling because a terminal short could disable the entire bus. Direct stubs can also cause significant impedance mismatches on the bus. Therefore, bus couplers are recommended because their isolation transformers and resistors are external to the terminal device. Compared to direct coupling, bus couplers extend the stub length to 20 feet and provide electrical isolation, better impedance matching and higher noise rejection characteristics. The electrical isolation prevents a terminal fault or stub impedance mismatch from affecting bus performance. All devices, including the bus controller, bus monitor and remote terminal, must be connected to the stub ends of the coupler.

What Type of Bus Couplers are Available?

admin — Wed, 10 Jun 2009 13:21:45 +0000

Bus couplers are available in various stub configurations including:

• Box type (used in lab or vehicle applications)
• In-line type (used in vehicles where light weight and small size are important).

Why Does the Bus Need Termination?

admin — Wed, 10 Jun 2009 13:20:12 +0000

According to MIL-STD-1553B, the bus must be terminated at both ends of the cable with resistors equal to the cable characteristic impedance. The purpose of termination is to minimize the effects of signal reflections that can cause waveform distortion. If termination is not used, the communications signal can be compromised causing disruption or intermittent communications failures. Furthermore, both ends of the bus, whether it includes one coupler or a series of couplers connected together, must be terminated. Since typically 78 ohm cable is utilized, the terminators should contain 78 ohm resistors. Some couplers have built-in terminators and are generally used at the ends of the bus in multi-coupler applications. These types of couplers are mainly for vehicle applications as they limit the flexibility of test lab set-ups.

Should the Stub Ports be Terminated?

admin — Wed, 10 Jun 2009 13:17:51 +0000

In a lab application, unused stub ports on the coupler need not be terminated since the stubs have higher impedance than the bus. A high-impedance terminator (1000 to 3000 ohms) is sometimes used in vehicle applications to simulate a future load from an unspecified device. In both cases, an RFI cap over the unused stub is a deterrent to interference and/or dust.

What is the Characteristic Impedance of the Bus?

admin — Wed, 10 Jun 2009 13:16:05 +0000

Although MIL-STD-1553B specifies that the data bus should have a characteristic impedance between 70 and 85 ohms, industry has standardized on 78 ohms.