Below is a list of NICAM-728 coders ordered approximately from oldest to newest (date of first production units) that I have confirmed actually existed which may (or were confirmed) to have been used for Broadcast purposes.
Does not include multifunction test equipment capable of NICAM-728 modulation or modern FPGA / software based solutions as these are unlikely to have been used for large scale broadcast.
Philips PM5685 (encoder only), Philips PM5686A (modulator only), Philips PM5687 (encoder + modulator)
The oldest NICAM modulator I know of. First went into production in 1987. More information here.
Eiden 198A (encoder + DQPSK modulator)
I have no information about these. It is a very old school looking design but this particular unit has a date sticker on the rear saying 1998.
Solution Produced by RE Communications used by ITV and Channel 4 UK (encoder + SIS encoder + DQPSK modulator)
It is well known that the IBA had their own implementation of Sound-in-Sync built by RE Communications of Denmark. I ended up in contact with two retired engineers who went to considerable lengths to try and find some of the actual equipment but unfortunately it had all been disposed of. Above is the best they could find – two modules from the system. The NICAM audio coder and decoder. It is nice to at least see those! There is a video on YouTube which shows completed equipment as well as an interview with Graham Sawdy who oversaw the project. The final design went into production around 1990.
Varian LDM1903 (encoder + SIS encoder)
Went into production around 1990. There is more information about this solution here.
Rohde & Schwarz SBUF-E NICAM Module (encoder + DQPSK modulator)
Tektronix 728E (encoder + DQPSK modulator)
A later (mid 1990s) design.
Factum NC200A (encoder + DQPSK modulator)
Another later mid-1990s design. There is more information about this unit here.
Barco NE-728 (encoder + DQPSK modulator)
These were known to be used in Kordia transmitter huts in New Zealand. Went into production around 1995.
No good quality photos are available but there is a copy of the manual here.