These baluns and ununs can be used for impedance matching and also as End Fed halfwave antenna matching transformers to 50 or 75 ohm coax cable.
Elecraft KXPA100 HF Linear Amplifier RFI Kit - 4 Filters for RF In/Out, DC Power, Relay/PTT/Computer Control
This is a generic linear amplifier RFI kit for DC powered amplifiers. Works on many popular amplifiers including:
Specially designed for the Elecraft KXPA100 linear amplifier used with the KX3 and the Yaesu 817 radio (and others).
Included are the following chokes and installation guidelines:
RF Input: 1/2" Snap on – 2 turns of RG-8X size coax through center (use additional turns if using smaller cable)
RF Output: 3/4" snap on – 3-4 turns of RG-8X size cable (use additional turns if using smaller cable)1/2
Control or Relay Cable: 1/2" snap on – 2-3 turns thru center - ½” diameter hole
DC Power Line: 3/4" snap on – 2-4 turns of +/- DC cables through center