MLU FORUM - Wireless of the Week

Inevitably communication systems broke down and required repairs and adjustment. Great quantities of specialized test equipment was produced to ‘keep them running”. This week is one such piece of equipment.

The Test Set TS-26/TSM was an American made test unit that was the equivalent of a modern day multi-meter. I have used this particular set for decades when the hardware store ones my kids got me for Father’s Day crapped out, proving that things really were built better back in the day.

The Test Set TS-26/TSM weighs 8-1/2 lbs. and is housed in a wooden box 8-5/32” wide by 7-1/8” deep by 5-1/2” tall with a removable lid. It has a meter that reads volts at various settings and an ohmmeter powered by either a 4.5 volt or 45 volt battery, both housed inside the set under the face. Wires and probes were stored in a compartment on the left.

The primary use was to find faults in wire line communication systems (location of opens, grounds, crosses and shorts). It was also used as a simple volt-ohmmeter. The operator could determine with a reasonable degree of accuracy where faults were using various methods including a capacitance kick method (using either the 4.5 or 45 volt battery) or simple comparisons with breaks in known samples of wire. Laminated charts with readings to indicate where faults were likely to be found, temperature corrections and a wiring diagram were stored in the set’s lid.

While an American set, this particular one was adapted for Canadian use as indicated by the RCEME (Royal Canadian Electrical Mechanical Engineers) drawing numbers on the laminated charts in the lid.