Excellent link, John, thank you. It turns out to be a Wireless Set 38 AFV. Also found a schematic on line ( http://www.vk2bv.org/radio/radio-files/ws-38-cct-a.gif ). It's more complex than I realized at the time, with one of the tubes both reflexed on receive and used as a microphone amplifier on transmit. 73, ian K3IMW