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Object Record

Catalog Number 06.0019.005
Title Radiometer Conductivity Meter CDM3
Description 06.0019.005.01 - conductivity meter
06.0019.005.02 - electrode
06.0019.005.03 - syringe

.01 Metal with two-tone green enamel. The instrument is a rectangle standing on its long, narrow side with a slightly slanted control board. The right side has a receptor for a 9-prong plug. The left side is solid. The back has maker’s sticker: "Made in Denmark, Radiometer" and inserts for measuring cell connector; T.C. Cell connector; green and red prongs; and recorder. There is also a dial for "Cable Cap. Comp. adj. to Min. meter defl." and a power cord. The front has a readout display of 0-5 and 0-1.5; power light; on/off switch; T.C. Compensation switch; meter range dial; cell constr. corr % dial; and lock dial. "Berger" is written on the front. The top has a metal plate with "U.S. Factory Representative, The London Company, Westlake, Ohio, Made in Denmark."

.02 Male prong connector attached by black insulated wire to an electrode (glass tubes with bulb end and flared arm where it connect to the syringe). In black on white insert is maker’s name and "Type CDC 314, Nominal Cell Constant 0.316 cm."

.03 Plastic 5cc Becton, Dickinson and Co. syringe with narrow tubing on end.
Object Name Meter, Conductivity
Date circa 1970
Accession number 06.0019.005
Caption Radiometer Conductivity Meter CDM3
Catalog date 2006-09-15
Catalog type History
Provenance Dr. Robert Berger, NHLBI LTD, used this analog bench model instrument in his studies of hemoglobin to see isoionic proteins were stripped off the molecule. The syringe was used to force solution through the bottom to the conductivity electrode. From "Manual: Conductivity Meter CDM3," Radiometer, undated: "The CDM3 Conductivity Meter is principally an ohmmeter which measures using alternating current. The apparatus utilizes an oscillator which sends a current through a measuring cell containing a liquid of unknown resistance. A regulation circuit holds the voltage across the measuring cell constant, and the current flowing through the liquid is read out on a meter."
Number of images 1
Updated 2017-03-10
Condition Very Good
Organizations NIH; NHLBI, Laboratory of Technical Development
NIH Property # 760922
Old NIH Property # 322808
Serial # 178969
People Berger, Robert L.