The Heathkit Oscilloscope Calibrator, Model IG-4505, is a precision instrument designed to provide accurate, crystal-controlled, fast-rise square wave signals for calibrating oscilloscopes. It produces various time and amplitude signals, making it suitable for calibrating Heathkit oscilloscopes as well as most other oscilloscopes. The calibrator serves as a reliable bench standard for testing and experimental circuits.

Function Description:

The IG-4505 generates both time (or period) signals and amplitude signals. The time signals are fast-rise (less than 4 ns) square waves, which are essential for adjusting oscilloscope sweep speed, delay line terminations, and high-frequency compensation. The amplitude signals are crystal-controlled, providing accurate vertical calibration and attenuator compensation. The device is designed to be user-friendly, with clear instructions for assembly, operation, and maintenance.

Important Technical Specifications:

Time Output Signal:

Range: 0.5 s to 1 µs square wave in a 1-2-5 sequence.
Accuracy: 0.01%.
Amplitude: 200 mV peak (approx.).
Rise Time: < 4 ns.
Overshoot: < 3%.
Output: 50 Ω terminated cable.

Voltage Output Signal:

Ranges: 1 mV to 100 V peak square wave.
Accuracy: Within 2% into a 1 MΩ load when referenced to the 1V position.
Rise Time: < 2 µs.
Frequency: DC, 2 Hz to 10 kHz in a 1-2-5 sequence.

General Specifications:

Internal Voltage Reference: 5 volts ±1%.
Power Requirements: 120/240 VAC, 50/60 Hz, 12 watts.
Dimensions:
- Height: 7 cm (2-3/4 in.).
- Width: 23.2 cm (9-1/8 in.).
- Depth: 10.8 cm (4-1/4 in.).

Usage Features:

The manual provides a comprehensive step-by-step assembly guide, making it accessible for individuals with varying levels of experience in electronics. It emphasizes safety warnings, particularly regarding soldering and lead trimming, to prevent eye injury and ensure proper connections. The assembly process is broken down into logical sections, including resistor, capacitor, diode, transistor, control-switch, and hardware installation, followed by wiring instructions. Pictorials are extensively used to illustrate each step, ensuring clarity and reducing the chance of errors.

For operation, the calibrator features controls for input attenuation, time base, and multiplier settings, allowing users to select the desired output signals. The calibration section details how to adjust the calibrator to ensure its accuracy, including procedures for setting the CAL control and verifying output waveforms. The device is designed for ease of use in a laboratory or workshop setting, providing a stable and accurate reference for oscilloscope adjustments.

Maintenance Features:

The manual includes a dedicated troubleshooting section to help users diagnose and resolve common issues that may arise during or after assembly. This section provides a systematic approach to identifying problems, starting with general visual checks and progressing to more specific circuit tests. It covers common problems such as unsoldered connections, "cold" solder connections, protruding leads, and issues with transistors, integrated circuits, and tantalums.

A detailed "Test #1 Start Here" flowchart guides users through a series of checks to pinpoint the source of a malfunction, covering various components like the pilot lamp, emitter and collector voltages, and signals at different IC pins. Subsequent tests (Test #2 and Test #3) focus on specific output signal parameters, such as 1000 Hz (1 mS) signals and voltage levels at different circuit points, to ensure the calibrator is operating correctly. The manual also provides detailed circuit descriptions and X-ray views of the circuit board, which are invaluable for advanced troubleshooting and repair. Identification charts for diodes, transistors, and integrated circuits, including their part numbers and basing diagrams, further aid in maintenance and component replacement. The Heath Company offers replacement parts, and the manual includes forms for ordering these parts, ensuring long-term usability and support for the device.

Heathkit IG-4505 - Page 46

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