Please help - identify the device (calibrator) from some Soviet connecting device. I have this piece in my collection, but I don't know what it actually comes from or what it was used for. The mounting is 2 x 2P29L and 2Ž27L mounted to be two crystals (1500 and 1000 kHz), I have only one. the power connector contains only the ground, heater and anode leads. The signal output is on the left side of the friction contact. Thank you, Miro