Keleket K-191 Pocket Dosimeter and Two Unknown Keleket Models
While most manufacturers were happy to produce black or metallic-colored dosimeters, Keleket dosimeters also came in rich blues, greens and reds.
In the accompanying photograph, the long red dosimeter employs a 0-50 R scale while the blue dosimeter covers 0-10 R. Each of the two is 5.25” long and 0.5” in diameter and each has a highly stylized pocket clip resembling a pen nib. The barrel of the red dosimeter is stamped “T101” and the barrel of the blue one is stamped “R173.” They were probably manufactured in the late 1940s.
The shorter maroon-colored dosimeter (4.25” long and 0.5” in diameter) is a Keleket Model K-191 and has a range of 0-20 R. The pocket clip is stamped Keleket but the scale, as viewed through the eyepiece (see right), identifies the manufacturer as Tracerlab-Keleket. Since the Tracerlab merger with Keleket took place in 1951, the dosimeter must have been produced sometime later (ca. mid 1950s).
One unusual and primitive feature of the blue and red models is the threaded cap used to protect the charging contact. Caps were always used with pocket chambers but only occasionally with pocket dosimeters. In the photograph below left, we see the threaded protective cap on the end of the red dosimeter and the unprotected standard charging contact at the end of the Model K-191 maroon dosimeter. The protective cap has a small circular glass window in it so that it doesn't have to be removed to read the dosimeter.
The photograph to the above right shows the end of the red dosimeter with the protective cap removed. Another unusual feature of the red dosimeter is that the charging contact is permanently connected to the dosimeter fiber—it doesn't use a bellows.