General
The Dynalyzer IV High Voltage Unit is capable of providing isolated signals analogous to:
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- Anode, Cathode, and Anode + Cathode tube voltages
- Anode Current
- Filament Current (AC)
These signals may be viewed on an oscilloscope, may be measured with Accu-Dyn+ system or peak-reading voltmeter, or may be processed and displayed with the Dynalyzer Digital Display(discontinued).
This unit has been designed as a calibration instrument and as a diagnostic tool for servicing x-ray equipment.
This unit is designed for continuous duty, and may be left in the high-voltage circuit indefinitely. This feature is desirable in special applications where frequent calibration is required.
This unit is portable. It weighs 14 kg (32 pounds) and is designed to simplify servicing and repair.
Basic Principle of Operation
The Dynalyzer High Voltage Unit is built in two sections. All high-voltage components are located in a tank pressurized with 30 psig of Sulfur Hexafluoride (SF6) gas. In the base of the unit are power supplies and buffer amplifiers to adjust the levels of the isolated signals, provide buffering against cable and instrument loading effects, and provide frequency compensation. In addition, there is an oscillator, which in conjunction with a high-frequency isolation transformer located in the tank, provides power to operate the anode-current sensing system.
Anode Current Sensor
The anode current sensor is an optically-coupled device that is capable of providing an isolated signal that represents the anode current waveform. Both analog and digital outputs are available. The sensor is capable of measuring current in the range of 0.5 mA to 1 Amperes with a 0.2% absolute accuracy. The output conversion factor for the analog output is 1 mV/mA for radiographic and 20 mV/mA for fluoroscopic measurements. The insertion impedance of the unit is 42 ohms ±5%. The average power rating of this resistor network is 21 watts, and is the only duty cycle limitation on this unit. The duration should not exceed 1 second at 1000 mA.
High-Voltage Divider
The divider consists of two 1000-megohm sections that are connected between the anode and ground, and the cathode and ground. Each section contains five 200-megohm resistors connected in series. The geometry of the structure provides distributed capacitance that provides a frequency response of 100 kHz.
Filament Current
Filament current is measured in the common lead of the cathode circuit using an insulated AC/DC open loop hall effect current transducer. The output of the transducer is amplified to a signal level of 0.1 Volt(pp)/Ampere(pp), with a -3-dB bandwidth of 20 kHz.
Equipment Supplied
As supplied, the High Voltage Unit is shipped with the following components:
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- High Voltage Unit Assembly
- 12 ft. Coaxial Cable, BNC Connectors each end (2 each)
- Vaporproofing Compound (2 [two] 1.5 oz. tubes)
- Line cord (6 ft.)
- Dummy plugs (2)
Additional equipment required for use includes:
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- Dual-trace oscilloscope to display mA and kV waveforms Optionally, a peak holding digital voltmeter (DVM), Dynalyzer III Digital Display or AccuDyn+ system
- Two (2) 3-conductor, 5-foot long high-voltage x-ray cables, Federal Standard Connector