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.
50 ohm coax to 75 ohm balanced output baluns are useful for low (< 1 wavelength) dipoles exhibiting 75 ohm characteristic impedance or for matching to balanced ladder line whose endpoint impedance is near 75 ohms.
50 ohm coax to 75 ohm CATV coax connections are easily done with a 1.5:1 unun with SO-239 connectors on input and output. Likewise 50 ohm coax to unbalanced verticals or loads near 75 ohms can be matched with a 1.5:1 unun.