GrahamH's photos with the keyword: analog

A two page test report for the transmission links for a two-way radio system. The links joined the track-side base stations and the control centre. The system is no longer in use. This is used for checking the links shown here: www.ipernity.com/doc/grahamh/24117033 E&M signalling over copper pairs in Australia was done using the 4W (1 pair each direction for the audio signal) circuit, ie no additional conductors. This is done in a similar manner to that used in feeding DC power to a condenser/electret microphone in a public address or studio sound system. The direct current for the signalling flows one way equally on both wires of a pair with the earth being used as the return conductor.

A two page test report for the transmission links for a two-way radio system. The links joined the track-side base stations and the control centre. The system is no longer in use. This is used for checking the links shown here: www.ipernity.com/doc/grahamh/24117033

The multimeter from my teen years, a Sanwa U50d. It has the standard ranges for the era. Sensitivity is 50uA with 20K ohms for DC and 8K ohms for AC volts. See note.

The multimeter from my teen years, a Sanwa U50d. It has the standard ranges for the era. Sensitivity is 50uA with 20K ohms for DC and 8K ohms for AC volts. See note.

A test sheet used to record basic measurements on a 4 wire plus E & M circuit. For this project the functionality was mostly derived from either two pairs of copper wires or a 64K slot from a 2M PDH stream. The links connected train radio base station controllers with the central control for the railway route. See www.ipernity.com/doc/grahamh/24117033/in/group/873405

Old work. Colour coding for wire used at PMG / Telecom Australia sites to interconnect various controls and alarms which were part of analogue microwave radio links - 1960s to 1980s. IDF = intermediate distribution frame, a bank of terminals for cables from equipment which enable interconnections to made and varied as needed.