El-Tronics CD V-710 "Rad-Tek" (1954-1955)
The fine print on the side of the case (see above) states that this meter was "distributed by Sears Roebuck & Co." When Sears sold other El-Tronics survey meters using the "Tower" brand, they dropped the El-Tronics model designations and replaced them with their own. This example may have been distributed by Sears before they developed the Tower brand. Although there is no reference on the instrument to the El-Tronics model number (the SID-1), there is no corresponding Sears model number, only the name "Rad-Tek" and the Federal Civil Defense Agency (FCDA) item number CD V-710.
It seems possible that this example was originally produced for the FCDA as the CD V-710 Model 1 ion chamber survey meter. There are circular marks on one side of the case where the original civil defense logo used to be. In addition, the original serial number (#1918) on the schematic inside the case was crossed out and replaced with a new number (#142). On the other hand, the text on the side of the case (photo above) appears to be original, and it is different from the Model 1's text. All in all, it is a bit of a mystery.
The "Rad-Tek" CD V-710 was a medium-high range survey meter that employed a hermetically sealed ionization chamber located in the bottom front end of the case. Since the chamber was not open to the atmosphere, the unit was largely unaffected by humidity or temperature and pressure changes. A zero adjust control was located on the top of the case below the range switch.
The earliest reference I have found for the "Rad-Tek" is the following product description in the May 1954 issue of Nucleonics: "The Rad-Tek ionization-type survey instrument, approved by the Federal Civil Defense Administration, measures intensities of 0.02-50 r/hr. It operates on flashlight and hearing-aid batteries said to be capable of giving over 100-hr operation." There is no mention of the 710 designation, but the photo accompanying the product description shows the circular civil defense logo on the side of the case.
A product announcement like this one suggests that the "Rad-Tek" was sold on the commercial market. This is also suggested by the fact that the Rad-Tek was described in a 1955 publication, Atomic Radiation Detection and Measurement, along with other commercially available instruments. The book describes the instrument as follows "The "Rad-Tek" Model SID-1, Manufactured by El-Tronics, Inc. was designated especially for use as a civil defense instrument." Interestingly, the collection has another "Rad-Tek" that came from a state civil defense stockpile. If, as seems to be the case, the Rad-Tek was sold to the general public, it might also have been used by the states as a substitute for the SID-1.
One neat thing about the Rad-Tek is the battery check feature—it is the earliest survey meter that I know of to have this capability.
Detector: Ionization chamber
Ranges: 0-0.5, 0-5 and 0-50 R/hr
Batteries: One 1.5-volt D cell, five 22.5-volt hearing aid batteries (#412)
Size: 7" x 3.75" x 7.75"
Weight: 3 lbs. 12 oz.
- El-Tronics. Instruction and Maintenance Manual for Radiological Survey Meter SID-1 (FCDA #CD V-710). No date.
- Renne, H.S. Atomic Radiation Detection and Measurement. ADR-1. July 1955. Howard W. Sams & Co. Photofact Publication.
- Product announcement. May 1954 issue of Nucleonics. Page 80.
- Atomic Energy Commission. Radiation Measuring Instruments and Associated Components. RIB-8 (Part 2). July 1, 1954. Page SGM-114A.
Please contact me (Paul Frame) if you have any additional information: (865) 576-3388 or Paul.Frame@orau.org.