I have placed this under New as it is new to me, though decades old in the workings.
Test Set No.1 is a military version of Model 8 Mark 2 housed in a radiation protective steel case. It incorporates a fuse on low ohms ranges. The ranges are from 3-10 instead of 2.5-10 with top terminals respectiveley at 3000v. There is no dB scale and the resistance scale is located at the bottom. There are no LR or Ins options.
DC 3, 10, 30, 100, 300, 600, 1000, 3000 volts - sensitivity 50 uA
DC 0.05, 0.3, 1, 10, 100 mA, 1, 10 A
AC 3, 10, 30, 100, 300, 1000, 3000 volts - sensitivity: 1 mA on 100+ volts, 3 mA on 30, 10 mA on 10, 30 mA on 3
AC 10, 100 mA, 1, 10 A
R 2k, 200k, 20 M ohm (20, 2k, 200k ohm center)
See also :richardsradios.co.uk
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However, the AVOmeter HR had additional 2500 V (AC) and (DC) ranges which used the corresponding 1000 V ranges, and were connected through two additional terminals at the top corners of the front panel. This feature was continued in the Model 8 and, with an increase to 3000 V to match their 1 - 3 - 10 ranges sequence, in the Model 9, Marks II and IV and the Model 8 Mark V. The 3000 V ranges were deleted in the Model 8 Marks 6 and 7 due to concerns for compliance with contemporary safety standards.
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With the DC switch set to its "AC" position and the AC switch set to "DC", no current can flow through the instrument. However whenever any moving coil instrument is likely to be subjected to heavy shock in transit, it is good practice to damp the movement by short circuiting the moving coil using a heavy gauge wire connected across the terminals. On earlier Avometers, this may be done by short-circuiting the input terminals and selecting the most sensitive direct current range. The Model 8 Mark V, 6 & 7 were provided with an "OFF" position on the DC switch which both disconnected the meter's terminals and short-circuited the moving coil.