Leader LSG-215A Standard Signal Generator

1. General

The LSG-215A is a Standard Signal Generator utilizing a synthesizer system. It is designed to generate CW and FM/AM modulation signals within the frequency ranges of 30 to 120 MHz (A) and 100 kHz to 30 MHz (B).

2. Features

• Highly stable signals due to oscillation signal locking to a reference crystal oscillator.
• Output level adjustable from -10 to 120 dBμ (0 dB = 1 μV) in 1-dB steps.
• Internal memory (battery-backed) stores 100 points of frequency, modulation type, and output level combinations.
• Frequency and output level settings are accessible via ten-key operations.
• Peak indication system for the meter circuit ensures accurate composite signal indication.
• Optional EPROM (2716 type) allows convenient storage of predetermined frequencies for service stations or production lines.
• Remote control capability for operations like memory recall via a 36-pin connector on the rear panel.

3. Specifications

Frequency

• Range: 0.1 to 30 MHz and 30 to 120 MHz
• Indication: 6-digit digital indication
• Accuracy: 0.1 to 30 MHz: 100 Hz; 30 to 120 MHz: 1 kHz
• Drifting: Within ±5 x 10⁻⁵

RF Output

• Range: -10 to 120 dBμ (0 dB = 1 μV, open terminal)
• Indication: 3-digit digital indication
• Reference level accuracy: Within ±1 dB at 120 dBμ
• Attenuator accuracy: Within ±1.5 dB (more than 0 dBμ), Within ±2 dB (less than 0 dBμ)
• Output impedance: 50 Ω, VSWR less than 1.2
• Spurious output: Less than -30 dB

Modulation

• Internal modulation frequency: 400 Hz, 1 kHz (within ±1%)
• External modulation input impedance: Approx. 10 kΩ
• FM:
  • Frequency deviation: 0 to 100 kHz (for carrier > 1 MHz)
  • Deviation indicator: 5, 10, 50 & 100 kHz full scale
  • Indicator error: 1 to 120 MHz; ±10% of full scale
  • Distortion rate: Less than 0.2% for 75-kHz deviation (demodulation band 80 Hz to 100 kHz)
  • External modulation frequency range: 20 Hz to 100 kHz (±1 dB reference 1 kHz)
• AM:
  • Modulation rate: 0 to 50%
  • Modulation meter: 5, 10, 50 & 100% full scale
  • Meter error: ±10% of full scale
  • Distortion rate: Less than 1% at 30% modulation (0.1 to 30 MHz), Less than 3% at 30% modulation (30 to 120 MHz)
  • External modulation frequency range: 20 Hz to 10 kHz (±1 dB reference 1 kHz)
• Residual Modulation (S/N):
• FM component: More than 70 dB (for 75-kHz deviation)
• AM component: More than 50 dB (for 30% modulation rate)

Preset

• Stores 100 points of frequency, modulation type, and output level combinations using internal memory.
• Optional EPROM unit available for programming.

Miscellaneous

• Power voltage: 100, 120, 220, and 240 V AC
• Power consumption: Approx. 30 VA
• Size and weight: 400(W) x 100(H) x 300(D) mm, 7 kg
• Accessory: 1 output cable (50 Ω BNC 3D-2V)

4. Notes on Use

Power Voltage

Ensure the power supply voltage is within ±10% of the rated voltage. Voltages outside this range may cause improper operation or damage to the power unit. Refer to the rear panel for fuse ratings and consult Figure 4-1 and Table 4-1 for power transformer wiring and voltage range specifications.

Table 4-1: Power Voltage Ranges

Battery Back Up of the Memory

The internal memory is battery-backed to retain data for over a month without power. If the instrument is unused for longer than a month, recharge the memory by supplying power for at least 8 hours before writing new data.

Input/Output Cable Connection

• Avoid applying external voltage to the output terminal, as this can damage the internal attenuator circuit.
• The external modulation input terminal should not receive voltages exceeding 5 Vp-p. If the DC component of the input signal exceeds ±2 V, use a condenser to eliminate it.

5. Description of Operating Keys and Switches

Circled numbers in this manual refer to operating keys and switches as shown in Figures 5-1 and 5-2.

5.1 Display Section

• (1) POWER switch: Pushed in for ON (indicated by 'ON'), pushed out for OFF. Activates RECALL mode upon power-on.
• (2) METER RANGE switch: Selects the range for the modulation rate meter (5, 10, 50, 100%).
• (3) Modulation rate meter: Indicates AM modulation rate (%) and FM deviation (kHz). Inner graticule for 5 & 50% (kHz), outer for 10 & 100% (kHz). Maximum AM modulation rate is 50%.
• (4) ADDRESS indication: Displays the current memory address (0-99) when not in LOCAL mode.
• (5) FREQ range indication: Automatically indicates the selected frequency range (A: 30-120 MHz, B: 0.1-30 MHz). Blinks if the frequency is out of lock range.
• (6) FREQUENCY display: Shows the set frequency in 6 digits (MHz).
• (7) OUTPUT display: Shows the output level in 3 digits (dBμ).

5.2 Output Level Variable Section

• (8) OUTPUT terminal: RF output terminal (BNC connector).
• (9) 10-dB output level keys: Increase/decrease output level in 10-dB steps.
• (10) 1-dB output level switch: Increase (clockwise) or decrease (counterclockwise) output level in 1-dB steps. Continuous rotation.

5.3 Frequency Variable Section

• (11) DIGIT SELECT key: Selects the digit to be changed. The selected digit is indicated by an LED.
• (12) FREQ UP/DOWN switch: Changes the selected digit's value. Clockwise turn increases frequency, counterclockwise decreases. Continuous rotation.

5.4 Program Section

• (13) FREQ key: Entry key for setting frequency data using the ten-key.
• (14) FREQ RANGE key: Switches between frequency ranges A (30-120 MHz) and B (0.1-30 MHz).
• (15) Ten keys: Used for entering frequency data after selecting LOCAL mode and pressing the FREQ key.
• (16) LOCAL key: Enables front panel control, overriding memory contents. Indicated by an LED. Releases RECALL mode.
• (17) RECALL key: Recalls stored memory contents. Indicated by an LED. The current address is displayed. Releases LOCAL mode and deactivates ten-key input.
• (18) STORE key: Writes set data (frequency, output level, modulation type) into memory. Address increments automatically after writing.
• (19) SET key: Prepares the instrument to store data. Releases LOCAL mode.
• (20) ADDRESS variable switch: Increments (INC) or decrements (DEC) the memory address.
• (21) ADDRESS RESET key: Resets the address to the starting position set by the BEGIN ADDRESS switch.
• (22) BEGIN/END ADDRESS switches: Define the memory address range (0-99). Ensure BEGIN < END.

5.5 Modulation Section

• (23) AM key: Selects AM modulation mode.
• (24) AM MOD level: Adjusts AM modulation rate (0-50%).
• (25) FM key: Selects FM modulation mode.
• (26) FM MOD level: Adjusts FM modulation deviation (0-100 kHz).
• (27) MOD ON/OFF key: Toggles modulation ON/OFF.
• (28) 1 kHz (INT) key: Selects 1 kHz internal modulation frequency.
• (29) 400 Hz (INT) key: Selects 400 Hz internal modulation frequency.
• (30) EXT key: Selects external modulation mode. Input signal at EXT MOD terminal becomes active.
• (31) EXT MOD terminal: BNC connector for external modulation input.

5.6 Rear Panel

• (32) RANGE OUTPUT: Control terminal for LSS-5011 Output Selector (5 V, 50 mA source for 30-120 MHz).
• (33) ROM UNIT: Slot for optional ROM UNIT 217-U01.
• (34) GND: Ground terminal connected to the frame chassis.
• (35) REMOTE CONTROL: Connector for the LSG-215-01 Remote Controller.
• (36) Fuse: Fuse holder. Refer to the seal for fuse data.
• (37) Cord winder: For winding the power cord.

6. Basic Operation

6.1 Operation of Frequency Setting

Frequency setting involves using the ten keys or the FREQ UP/DOWN switch. The frequency range, display, and resolution are detailed in Table 6-1.

Table 6-1: Frequency Range, Display, and Resolution

Warning: A flashing LED in the upper two digits of the frequency indication signifies that the set frequency is out of range. Ensure the frequency is set within the correct range.

A. Use of Ten Keys

To set a frequency, e.g., 98.0 MHz:

1. Press the LOCAL key (16).
2. Press the FREQ key (13).
3. Press the RANGE key (14) to select range A (30-120 MHz).
4. Enter the frequency using the ten keys: 0, 9, 8, 0, 0, 0. The FREQUENCY display will update accordingly. Leading zeros for values less than 100 MHz (Range A) or 10 MHz (Range B) are displayed as blanks but should be entered as '0'.

B. Use of FREQ UP/DOWN Switch

This switch operates in both LOCAL and RECALL modes.

1. Specify the digit to be changed using the DIGIT SELECT key (11). The selected digit's position is indicated by an LED. The highest digit cannot be selected.
2. Adjust the frequency using the FREQ UP/DOWN switches (12). Digit position selection can be automatic.

6.2 Operation of Output Level Setting

The output level is displayed in 2 digits (dBμ) and can be set from -10 dBμ to 120 dBμ in 1 dB steps. Refer to Section 5.2 for operation details.

6.3 Operation of Modulation Setting

This section allows selection of five types of output signals:

1. CW (Carrier Wave)
2. Internal modulation FM
3. External modulation FM
4. Internal modulation AM
5. External modulation AM

6.3.1 CW (Carrier Wave)

Turn off the MOD ON/OFF key (27). No LED indication.

6.3.2 Internal Modulation FM

1. Turn on the FM key (25).
2. Turn on either the 1 kHz (INT) key (28) or the 400 Hz (INT) key (29).
3. Turn on the MOD ON/OFF key (27).
4. Adjust the modulation level using the FM MOD level knob (26). Note the METER RANGE selection.

6.3.3 External Modulation FM

1. Turn on the FM key (25).
2. Turn on the EXT key (30).
3. Turn on the MOD ON/OFF key (27).
4. Apply the external modulation signal to the EXT MOD terminal (31).
5. Adjust the modulation level using the FM MOD level knob (26). The modulation rate meter (3) displays the composite signal level. Approximately 75 kHz deviation is achievable with a 3 Vp-p input.

6.3.4 Internal Modulation AM

1. Turn on the AM key (23).
2. Turn on either the 1 kHz (INT) key (28) or the 400 Hz (INT) key (29).
3. Turn on the MOD ON/OFF key (27).
4. Adjust the modulation level using the AM MOD level knob (24). The maximum AM modulation rate is 50%.

6.3.5 External Modulation AM

1. Turn on the AM key (23).
2. Turn on the EXT key (30).
3. Turn on the MOD ON/OFF key (27).
4. Apply the external modulation signal to the EXT MOD terminal (31).
5. Adjust the modulation level using the AM MOD level knob (24). Approximately 30% modulation rate is achievable with a 1.7 Vp-p input.

6.4 Preset Operation

Presetting involves storing frequency, output level, and modulation type data into the instrument's memory (100 points, addresses 0-99). The modulation rate and METER RANGE cannot be stored.

6.4.1 Preset Procedure

1. Select LOCAL mode using the LOCAL key (16).
2. Set the desired frequency, output level, and modulation data.
3. Press the SET key (19) to prepare for data storage. The ADDRESS display shows the current address.
4. Set the BEGIN and END addresses using the BEGIN/END ADDRESS switches (22). Ensure BEGIN < END.
5. Press the ADDRESS RESET key (21). The ADDRESS display shows the starting address.
6. Press the STORE key (18) to store the data. The address automatically increments by 1.
7. Repeat steps 1, 2, 3, and 6 for successive presetting.

6.5 Recall Operation

Recall operation retrieves stored memory contents.

1. Press the RECALL key (17).
2. Select the desired address using the ADDRESS variable switch (20) (increment clockwise, decrement counterclockwise). The ADDRESS RESET key (21) can be used to quickly access the starting address. The current address is displayed.

6.6 ROM Unit

An optional ROM unit (215A-U01) is available for storing and operating multiple signal generators with identical program contents. Refer to the 215A-U01 instruction manual for details.

7. Remote Control

The instrument can be operated remotely in RECALL mode, allowing random access to memory addresses. The remote connector is an AMPHENOL 57-30360.

7.1 Functions

• Direct random access of memory addresses (within BEGIN/END restrictions).
• Address increment/decrement by 1.
• Modulation ON/OFF control.
• Output level UP/DOWN control in 10-dB and 1-dB steps.
• Frequency UP/DOWN control via DIGIT SELECT.

7.2 Pin Connection of Remote Connector

Figure 7-1 illustrates the pin connections of the remote connector. Note that pins 6, 14, 16, 17, and 28-36 are unused. Signal levels for remote control should be +5 V.

7.3 Operation of Each Terminal and Switch

Detailed diagrams illustrate the operation of switches S1-S11 and their relationships for controlling the signal generator remotely.

8. Method of Use

8.1 Accessories for Measurement

Various accessories are available to enhance measurement capabilities:

• Remote control box (LSG-215-01): A compact box with BCD switches for direct memory address setting (up to 12 points), improving production line efficiency.
• Test loop (LPA-070): For measurements in the 100 kHz ~ 30 MHz range (50 Ω).
• Dummy antenna (LDA-1554-50): Converts 50 Ω unbalanced input to 300 Ω balanced output.
• ROM unit (215A-U01): For programming and operating multiple signal generators.

8.2 Use Examples

Figure 8-5 shows a typical connection diagram for measuring AM/FM receivers, following JIS specifications.

8.2.1 Measurement example of practical AM sensitivity

1. Connect the LSG-215A as shown in Figure 8-5 and set the radio receiver to AM mode.
2. Set the LSG-215A to LOCAL mode (16).
3. Set the output level to 35 dB using keys (9) and (10).
4. Set the RF frequency to 1.0 MHz using keys (15) or switch (12).
5. Select AM modulation using the AM key (23).
6. Turn on modulation using the MOD ON/OFF key (27).
7. Set internal modulation to 400 Hz using the 400 Hz (INT) key (29).
8. Tune the receiver and adjust its output level to a rated output (e.g., 1 W). The receiver output level is noted as 'S'.
9. Turn off the MOD ON/OFF key (27). The noise level is noted as 'N'.
10. Calculate the S/N ratio from 'S' and 'N'.
11. Measure the output level while decreasing the LSG-215A's output level. The output level at which the S/N ratio is 20 dB is the practical sensitivity.

9. Maintenance

This instrument is designed for stable, long-term operation. For repairs or calibration, contact an authorized LEADER service center or agent. The cabinet cover can be removed by unscrewing the four screws and two cord winders as shown in Figure 9-1.