United States Military
Radiac Training Set

US Military Issue Radiac Training Set
Measures 0 - 50,000 Milli-Roentgens Per Hour
Manufactured by: Tracerlab Inc. Boston, Mass.
Serial Number 1490
This model dates from around 1950

As a training unit, the AN/PDR-T1B is an ionization chamber instrument used to detect the presence
of gamma-emitting  radioactive materials, and to train operators in the use and maintenance
of this type of equipment.
This model has a built-in beta check source, activated by the control knob just to the right
 of the meter face. See photograph below for close up of beta check source.

Case Dimensions: 6.2" Wide x 10.4" Long x 8" Tall including handle.
Case is all steel. - Accuracy ± 15% - I did not receive the 1½" wide carry strap.
Controls include: Off / Battery / Set (zero) / 50K / 5K / 500 / 50 / 5

The switch for changing the scales is connected by cams and linkage to the meter face on which the
different scale ranges are indicated, much like the Victoreen 247-B. Each range is color coded, see below:
0 –5 Green / 0 –50 White / 0 – 500 Yellow / 0 – 5,000 Orange /  0 – 50,000 mR/h Magenta

Meter face is lit by a BA-42, 1½ volt battery placed in the handle post.

Left & Right Top Views

Left & Right Inside Views

Tracerlab also made a commercial version of  the AN/PDR-T1B, it was named the SU-10.

Inside View
Battery box is shown upper left, with layout shown in case. Batteries used include:
 Two BA-51, 67½ volt for the ionzation chamber supply. One BA-42 for meter illumination.
 One BA-1278/U Pack which supplies 5.2 volts for calibration, 45 volts for the plate supply and,
22.5 vots for the bias supply. One BA-1277/U supplies 1.3 volts for the filament.

Schematics are glued to the case bottom, wrench included is for adjusting the control linkage.
Click HERE for a large image of the schematics.

Close Up Views Of Meter & Controls
The round knob on the handle unscrews and holds a battery to light the meter face.
The color of the scale is different with each range.

View of beta check source & meter lamp.
Check source is rotated 180 degrees to place it under a thin spot of the ion chamber, note it is
spring loaded to return when knob is released.

The AN/PDR-T1B in use, photograph from:
Technical Manual TM 11-5514  -  May 1951

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