Clarke-Hess Communications Research Corp., founded in 1969, is an electronics test and measurement company specializing in dc/low frequency applications. The company’s customers include the world’s national standards laboratories, military agencies and commercial and industrial firms. Dedicated to precision instrumentation, Clarke-Hess has earned a reputation for quality, service and outstanding performance.
The specific areas in which the company specializes are included in the following sections.
The Model 2335A and the Model 2335A-01 Power Analyzers cover a frequency range from dc to over 1000kHz. These instruments have wide voltage and current ranges and are able to make precise measurements under difficult signal conditions. Typically, most power analyzers have very poor performance at high frequencies and /or low power factors. The family of Clarke-Hess power analyzers overcomes these problems.
Customers of the Clarke-Hess power analyzers include most of the computer, aircraft, telephone, power supply, electric locomotive, transformer, ferrite, fluorescent lamp and lamp ballast, ultrasonics, and motor control companies throughout the world. They include any company that needs to measure the loss in iron core or ferrite components, the loss in electronic lamp ballasts, the loss in capacitors, or the power in any sort of distorted, low power factor, or broadband wave-shape. They are also used in modern university teaching laboratories.
The Model 5600 Digital Phase Angle Standard is now generally accepted as the world standard for phase generation. The instrument offers two digitally controllable sine waves with a relative phase adjustable in 0.0001 degree steps over +/-999.999 degrees. The frequency range covered is from 1Hz to 1MHz with each channel having an adjustable amplitude from 50mV to 120.0V. Typical distortion is below -84dB over much of the range from 1Hz up to at least 10kHz.
The phase accuracy of the Phase Standards is traceable not only to intrinsic standards such as the Clarke-Hess Model 5002 but also to NIST and to NPL in England. In addition to these two laboratories, Clarke-Hess Phase Standards are in use by most of the national laboratories throughout the world.
In the U.S., other agency and commercial users of Clarke-Hess Phase Standards include N.A.S.A., the Army, Air Force, the Navy, Boeing, Rockwell, Honeywell, Curtis Wright, Dranetz/BMI, Fluke, TRW, LTV, Philips, Duke Power, Southern California Edison, Consolidated Edison, GEC/Marconi, Scientific Atlanta, General Electric and many other companies and testing laboratories.
PHASE METER, PHASE ANGLE VOLTMETER (PAV)
Since one of the uses of Phase Standards is to check Phase Meters and PAV’s, a natural outgrowth of the production of the Phase Standard was the introduction of the Model 6000A Phase Meter and Model 2600 Phase Angle Voltmeter (PAV). The Model 6000A measures the phase difference between two input signals from 5 Hz to 1MHz with a resolution of 0.001degrees. The Model 2600, in addition to measuring phase, also measures the in-phase, quadrature, fundamental and total components of an input signal. The unit also can measure AC ratios, impedance and power.
In head-to-head comparisons, the Model 6000A and Model 2600 have always proven to be far superior to the “similar” units manufactured by the competitors of Clarke-Hess.
PRECISION AC CURRENT SOURCE
The Model 515 High Accuracy AC Reference Oscillator fills a need for a relatively low cost and practical solution for supplying a reference excitation to calibrate LVDT and Synchro/Resolver Transducers. The Model 515 has built-in load sensing which, in effect, yields “zero” output impedance and virtually eliminates the effects of fluctuating output loads. With up to 15VA of output into loads with as much as 80° of phase shift, the Model 515 is ideally suited for driving inductive loads. Typical users include LVD/RVDT and Synchro/Resolver manufacturers and their customers.
VOLTAGE AND CURRENT SOURCES AND/OR CALIBRATORS
The Model 828 Voltage and Current Calibrator provides voltages from 1mV to 1100V and currents from 1A to 5.00A at dc and at frequencies of 50Hz, 60Hz, and 400Hz.
Accuracy in the 0.1% to 0.2% range makes the Model 828 suitable as a portable source for checking the calibration of analog meters as well as a source for calibrating 3 1/2 digit digital meters and as a general purpose voltage and current source. As such, it fills a niche between the more sophisticated, and much more expensive, calibrators produced by companies such as Hewlett-Packard and Fluke and the low level calibrators produced by several other companies.
The Model 828 is used by electric utilities, calibration laboratories, relay manufacturers, military services, service organizations, and all sorts of industrial users throughout the world.
The Model 8080 Multifunction Calibrator is an ideal and easy to use instrument featuring a variety of calibration capabilities. The instrument functions as a Voltage, Current, Power, Resistance, Capacitance and Thermocouple Calibrator. Having very high accuracy, it is ideal as a standard of these electric quantities in calibration laboratories. It also has the feature of supplying several different waveshapes in additional to the traditional sinusoidal output. This feature makes it ideal for testing meters which are true rms reading or crest factor sensitive. These signals are also suitable for the basic calibration of oscilloscopes. The calibrator has the capability of measuring temperature with TC and RTD temperature sensors. A built-in multimeter can be used independently or in simultaneous operation with the calibrator output.
The highest highest current product developed by Clarke-Hess is the precision, 100Ampere, 100kHz Transconductance Amplifier.
The Model 8100 generates output currents which are directly proportional to its input voltage over the frequency range from dc to 100kHz. The Model 8100 is highly stable for inductive as well as capacitive loads. The unit’s accuracy, high compliance and quick warm up exceed, by a wide margin, any other commercially available transconductance amplifier.
The high compliance output voltage of 7V rms for all ranges allows the series connection of shunts and current transformers, for comparison purposes, even with 100A at 100kHz. The Model 8100 is protected by both over-current and over-compliance circuits as well as by thermal cut-outs in the high current power supplies.
Typical customers include the U.S Air Force, the U.S. Army, the National Institute of Standards and Technology, the National Laboratory of Australia, Taiwan Power, Sandia National Labs, LCIE (French national lab) Boeing and PTB (the National Laboratory of Germany).
Clarke-Hess exhibits its products the National Conference of Standards Laboratories (NCSL). It presents technical papers at national, international, and specialized conferences and publishes technical papers in the leading technical journals. These papers are generally considered to be excellent application notes for our instruments. A list of these publications may be obtained by sending us an e-mail requesting them.
Kenneth Salz, who was previously the President of North Atlantic Instruments, is President of Clarke Hess. Dante Alessi joined the the company in 2005 as Vice President of Engineering.