Test set T-112; manufactured by Autophon AG, Solothurn.

The T-112 test set was developed by Autophon for alignment and repair on the SE-125 walkkie talkie radio. It was together with an assortment of spare parts contained in the crate repair and spare parts kit B for the SE-125.

• Principle: Stabilised power supply, AF oscillator 1000 Hz for modulation of the test signal, tunable RF oscillator 77.5 - 87.5 MHz.

• Mains operation: 220 V

• Universal instrument (multimeter) Elmes 20 for DC and AF signal measurements. The HF probe must be used for signal tracing.

The T-112 test set developed by Autophon is used für alignment and maintenance work on the Autophon SE-125 handheld radios. In the 1st or 2nd repair stage, only defective modules are localised by the troop signal mechanic, these are replaced from the spare parts kit and the function og the radio is checked. Repair work on the individual modules was only carried out by the manufacturer, the modules had to be sent nback tothe factory.

The SE-125 handheld radio to be tested is powered directly from the test set; in addition to the nominal voltage of 7.5 V, overvoltage and undervoltage can also be test. When working on the SE-125, its own battery must be removed. The radio is connected to the test set using a multi-pin connector, the headset (Mikrotel) has also to be connected to the test set, the radio can be switched to transmit mode directly from the test set without pressing the PTT button on the microtel.

In position 1 of the mode switch, the supply voltage (red marker) is measured and in position 2, the current consumption in transmit mode (green marker) is measured; in the event of an overload due to a short circuit, the red lamp lights up and an electronic protection turns off the power supply.

To measure the receiver stages, the T-112 is connected to the antenna connector; on the universal channel 7, it supplies 0.5 μV to the coax output.

To test the RF and AF receiver path, the radio to be tested is connected to the „0.5 μV HF 50 Ω“ transmitter output. The Elmes 20 multimeter with the RF probe is used for RF measurements; Regl. 56.529d indicates at which measuring points which levels are to be expected.

In position 6 of the mode switch, the modulation of the RF oscillator of the T-112 on channel 7 or 77.7 MHz is checked, in position 7 the RF voltage of the RF oscillator.

In position 8, the current consumption of the receiver branch is measured with the squelch switched on and off (yellow-black or yellow marks), in position 9 the AF output power and in position 10 the noise reduction at 0.5 μV RF power, which stands for testing the receiver sensitivity.

To measure the transmitter output, the antenna connector of the radio is connected to the coax socket. The transmitter power (blue mark) is indicated when the mode switch is in position 3, the standard frequency deviation is indicated in position 4 and the peak deviation of the SE-125 modulated at 1000 Hz in position 5.

A special RF output, which must be protected with a cover when not in use to prevent stray radiation, is used for signal tracking.

RF signal generator 77.5 - 87.5 MHz with modulation 1000 Hz, stabilised power supply.

The set is completely solid state.

The T-112 was developed for tuning and alignment work on the SE-125 radio set from Autophon, it was used by the Uem Gtm (signal mechanic) in the field workshops.

t-112.jpg

Best thanks for the use of the images to Toni Gämperle.

• The SE-125 radio, Regl 65.529d, instructions for signal mechanics; pages 128pp

• Documentation SE-125, A. Gämperle