ASM-2 Construction Guide
ELBY Designs - Laurie Biddulph
9 Follan Close, Kariong, NSW 2250, Australia
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Ring Modulator
Power up, Testing and Calibration Procedures
Setting up the circuit is quite straight-forward but needs to be done carefully. You will need
a 10V p-p sine or triangle wave of about 1kHz and either an oscilloscope, sensitive AC
voltmeter or an audio amplifier.
1. Monitor 'TP4 RING' of the Ring Modulator.
2. Apply the test signal to the [CARRIER] input (J1601 pin 1).
3. Adjust P1601 until the output signal is at minimum.
4. Apply the test signal to the [SIGNAL] input (J1601 pin 2).
5. Adjust P1602 until the output signal is at minimum.
6. Repeat steps (2) to (5) until no further improvement can be made.
The level of feed-through obtained will vary between IC’s. Typically, with a 10V p-p signal
the feed-through for the [CARRIER] input may be trimmed to between 10mV (-60dB) and
20mV (-54dB). For the [SIGNAL] input this will, typically, be between 40mV (-48dB) and
80mV (-42dB).
