449/449-2  Log/Lin Ratemeter

• Linear and logarithmic modes 10 to 10⁶ counts/s ranges
• 5-decade log range
• 0 to 100% zero suppression
• Positive or negative inputs (50 ns minimum width)
• Wide choice of time constants
• Optional audible output
• Accessory alarm capability

The ORTEC Model 449 Log/Lin Ratemeter provides two modes of operation: linear and logarithmic. The linear mode has 11 full-scale ranges from 10 to 10⁶ counts/s in 1-3-10 steps. The 5-decade log mode covers the range from 10 to 10⁶ counts/s in a single span. These selections permit logical operation of the instrument when measuring low, medium, or high steady pulse rates or when monitoring rates that vary through a wide range.

The unique, circular front-panel meter provides excellent readability for both modes because of the longer effective scale inherent in its 240° movement and because of the 2% accuracy of its indications.

Zero suppression is provided for up to 100% of any linear range. Any relatively constant background in the counting rate can be subtracted from the data by adjusting this control. Also, a suppressed zero will permit observation of rates that are beyond the nominal full-scale limit with greater accuracy than could be obtained by switching to a higher range. The choices between 7 linear and 2 log time constants is a further aid in accurately reading the rate of incoming signals.

The Model 449 measures the rate of either positive or negative input signals with a wide variety of pulse shapes. This provides the user with maximum flexibility in the selection of sources for input signals.

In addition to the front-panel meter indications, outputs are provided for both current and voltage recorders, as well as a high-level voltage output for control or monitor applications.

The Model 449 is available with an optional built-in audible output (Model 449-2), which has a sound frequency that is variable as a function of count rate. The range of sound frequencies is effectively 0 to 500 Hz and corresponds directly to the full-scale range of the front-panel meter. The audible output includes a threshold control to totally suppress all sound until the input rate exceeds the preselected audio threshold and a separate audio volume control to allow either local or relatively remote audible monitoring of observed rates.

For control and/or alarm applications, the Model 449 can operate an accessory ORTEC Model 461 Alarm Control or other device through its analog output.

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