Raycom 1553 Data Bus Transformers
The first MIL-STD-1553 data bus specifications were published by the United States Air Force in 1973 for the F-16 Fighting Falcon. Now, however, it is used extensively by many branches of the United States military, as well as for NATO.
The “Bus” itself is a wire pair that operates with an impedance of between 60 and 85 ohms at a frequency of 1 MHz. The actual data bus transformers are used in this specification where the transmitters and receivers couple. The transformer is used in tandem with a resistor to ensure that the bus does not conduct current through the aircraft. Also, it is used to reduce any impact from a short circuit.
There are only a few transformer manufacturers that are certified to produce the MIL-STD-1553 data bus transformers. This is mainly because it is a difficult specification to meet and an even more difficult one to become certified to build. Since this is used in flight applications, quality must be the primary focus in the manufacture and testing of these parts.
Furthermore, there are only about three companies that produce a transformer that can actually interface in all the various 1553 data bus circuits. There have been some compatibility issues identified with transformers and transceivers and Raycom Electronics has redone their design to address these specific issues. It is one thing to meet a specification, but quite another to have a product that will work in all the various types of applications. Raycom Electronics, is one of these companies.
There has been discussions over the years that fiber-optics would eventually make the 1553 data bus obsolete. but time has proved this to be incorrect. One of the main reasons being that fiber-optics would be almost impossible to repair. It is more likely that RF would eventually supplant the 1553 data bus, but that appears to be very far off in the future.