Dear Jerry aa1of,
The modification for suppress the spurious of this time is as follow.
I hope this would be useful for you.
1) Add 3.3uF electrolytic capacitor and 0.1uF x 2 bypass capacitor to VCC line of Arduino board =>PIC1-1a PIC1-2a
2) Insert high frequency choke of about 100 uH in the power line of Arduino =>PIC2a
3) Connect the minus line of power supply line to the ground =>PIC3-1a PIC3-2a
4) Connect the minus line of BITX40s to the ground
5) Add 0.1 uF × 2 bypass capacitor to VDD of BITX 40 board=>PIC5a
6) To prevent common mode noise, add 0.01uF x 2 bypass capacitor to the power connector=>PIC6a