The AN/URT-18 HF transmitter comprises an exciter plus 2.5 kw linear amplifier. The amplifier is an AM-2374/URT (Collins 204F-1) So what is the exciter nomenclature? - it has some common components with AN/URC-32 is the only clue I have. Was this transmitter used by the Navy? cheers, Nick K4NYW www.navy-radio.com