LDM #353: Radar Tuner TN-131/APR-9

This video shows the teardown and reverse engineering of a vintage Radar Tuner TN-131/APR-9. 00:00 - Intro 01:00 - Teardown 02:08 - Input filter 06:08 - FI preamplifier 08:00 - Mixer 10:48 - Servo control feedback potentiometer and reflector voltage setting 13:52 - Motor 15:38 - Frequency setting test 16:34 - Schematic diagram Technical description: It uses a 1N26 mixer diode and a 2K48 reflex klystron for the local oscillator. Frequency setting uses a DC motor and several devices linked to the output shaft: * A fixed cam permits to modify the frequency of the reflex klystron. * An adjustable cam permits to change the central frequency of the input filter * A potentiometer permits to change the reflector voltage of the klystron according to the frequency * Another potentiometer is connected to the connector, probably for the servo control of the frequency setting mechanism. * A synchro transmitter * An internal indication of the frequency using coding wheels Links: Klystron 2K48: Recorded 2023/10/31