The KAT100 ATU needs the control signals from the base K2 to turn on and function. So the answer is that it will only function with the K2. Yoou might consider the KAT500. 73, Don W3FPR On 5/26/2019 5:39 AM, Yoshida Akira wrote: > Hi all > > Does KAT100 ATU work with transceiver other than K2 ? > Thanks in advance >