Ferrite filter products can help speed up digital devices by suppressing common mode current from RFI sources OR prevent digital devices from emitting RFI on its connecting cables and power supply lines.
Elecraft KPA1500 HF Linear Amplifier RFI Kit - 15 Filters for RF In/Out, AC Power, PA KEY, Computer Control/AUX/RS232
KPA1500
This RFI Kit Includes are the following filters and installation guidelines:
RF Input:F240 ring – 5-9 turns of RG-58/8X size through center
RF Output:# 1 - FSB31-1 (Big Clamp on) – 3 turns of RG-8 size cable
RF Output:# 2 - FSB31-1 (Big Clamp on) – 3 turns of RG-8 size cable
PA KEY Cable: - FSB31-1/2 – multiple turns through choke – ½” diameter hole
DC Power Line: - FSB31-1 (Big Clamp on) – 2 turns through center
AC Line of DC Power Supply: - FSB31-1 (Big Clamp on) – 3 turns through center
Ports 7 to 15 : - FSB31-1/2 – multiple turns through choke – ½” diameter hole
Total ferrites: - F240 rings (1), FSB31-1 (4), FSB31-1/2 (10)
Also make sure you connect a good RF ground to the amplifier ground post.