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TS850 “NG CARRIER UNIT”
The next generation CAR UNIT for the Kenwood TS850 transceiver
I have developed this board as a aftermarked replacement for the Kenwood CAR UNIT (X50-3140-00) with four YM6631 and/or YM66312 DDS chips, which is no longer available as original spare part. Furthermore, there are no longer any of these chips available to replace the old ones:
The original Kenwood CAR UNIT board (X50-3140-00), installed in the TS850
The CAR UNIT do many different things in the TS850: from generating 4 different RF signals used as LO signals in the mixers – to even generating the side tone when sending CW or CTCSS sub tones in FM split mode.
To replace the original CAR UNIT, the new board was developed based on a high performance FPGA chip (Field Programmable Gate Array), which include the function of all 4 ASIC’s YM6631/YM66312 and some peripheral circuits in only one chip !!
First, all internal functions of the original YM6631 chip was completely reproduced as a VHDL model, including a DDS (Direct Digital Synthesis) and implemented in the FPGA with some improvements.
Due the high performance of the FPGA the functions of the peripheral circuits (mixers, ceramic filters etc.) could be minimized to achieve a higher design flexibility of this board. Furthermore, a high spectral purity of generated RF signals and matched output levels are the results of an accurate signal routing, PCB design and analog circuits:
The accurate design of all functions implemented in the FPGA for the communication with the TS850’s digital unit are high speed optimized and allow a glitch-free, smooth tuning operation.
The prototype of NG CAR UNIT board for the KENWOOD TS850:
All screw mounting holes are in the same location and all connector labels have the same description on the printed circuit board as on the original unit, which permit a easy “plug and play” replacement of a defectiv CAR UNIT. Furthermore there are no alignments necessary on the transceiver after the replacement of this board.
The development setup for the NG CAR UNIT board mounted in a KENWOOD TS850:
I have some pieces of this board, so for requests please send me an email.