How do you protect the mounted MU-4 from noise?

You need to consider noise from the unit itself and from the vicinity where it is mounted.

1. Mount the MU-4 on a sub-board as far as possible from noise sources.
2. Use a multilayer CPU circuit board, with the signal line on an inner layer. Shield it with a ground pattern on the front and back, to prevent leaks of noise radiation from the signal line.
3. Place shielding between the CPU circuit board and sub-board as a measure against noise.
4. Put noise filters in the power line and signal line that connect the sub-board and CPU circuit board (on the exit side of the CPU circuit board). The noise filters should have the maximum impedance at the waveband of the MU-4 used. The explanation is based on use of a sub-board, but similar measures are also required for a single board.