I can remember in the 1950s the "telephone company" man (there was only one then, company that is) using this meter as his standard tool.
When the "phone man" came to our house he would check for the number of ringers in our house and he had paper work saying how many phones we were paying for. I soon learned how to disconnect the ringer of a phone and add it to our line.
These were typically either 500 type dial sets or later 2500 Touch Tone sets, where the polarity mattered. If you had not signed up for touch tone and you house was wired properly by "the phone company" then installing a touch tone phone would not work because the polarity was reversed from standard practice. Since it really didn't matter to the dial phones the easiest way to become touch tone compatible was to just reverse the pair going into the house, then a touch tone phone would work anywhere. These were the days when the standard phone connector was a 4 pin plug. Much larger than today's modular connector.
This may also be known as the Northern Electric 324.
Is very similar to the TS-26 militry test set.
VoltsIt's recomended to start any test sequence by connecting the meter to the line and measuring voltage. This way you can confirm that the line either is or is not powered. If the line is powered when you think it is not, the other tests will be invalid.1. Turn "OFF" to read volts on "POINTS" scale (i.e. 0 to 100 VDC)
1. Turn meter on
2. Short leads
3. Adjust for red zero reading
4. Measure Ohms on red top scale
1. With meter "ON" and calibrated for Ohms
2. Switch back and forth the "REV" switch and note the POINTS change in reading
3. Distance (feet) =480 * # of POINTS change
Note: if the meter deflects off scale try using the BAT ADJ control to bring it back on scale, if this does not work then press and hold the R/10 button while switching back and forth.
Normal active line
1. One side (Tip) should have low resistance to ground.
2. The other side (Ring) should show about 50 VDC to ground
Detecting a bell
1. Disconnect line from telco Central Office (CO)
2. Measure Distance to tel set on ring wire (note # of points)
3. Measure Distance to tel set on tip wire (note # of points)
4. Connect leads to Tip and Ring and measure Distance
5. The # of points will increase by about 30 points for a conventional bell (40 points=.464 microfarads)
Locating an open with Distance measure
1. Disconnect from telco Central Office (CO)
2. From one end of pair measure Distance on Ring
3. From one end of pair measure Distance on Tip
4. If readings are about the same both wires may be open, if different one wire may be open
5. From other end measure Distance on Ring and Tip
The percent distance to the open is the distance from one end divided by the sum of the distances
Ground ConnectionFor a number of tests the instructions say to connect one of the test leads to ground. If a ground wire is handy this is easy, but often only dirt is available. In this case just plunge a screwdriver into the ground and clip onto it.
The Bell System Practices for the meter is: Outside Plant Construction and Maintenance, Section G10.400, Issue 1, August 1941.
page created 2 July 2003.