Belar AMM-2C AM Modulation Monitor

BELAR AM MODULATION MONITOR, MODEL AMM-2C

DESCRIPTION

The Belar AMM-2C Modulation Monitor is a precision, all solid-state AM demodulator designed to measure the modulation characteristics of AM broadcast transmitters over a frequency range of 260 kHz to 50 MHz. The AMM-2C utilizes a unique carrier-referencing system for the peak flasher indications. Peak flasher accuracy, as well as modulation alarm sensitivity, is independent of carrier level over more than a ą30% range. A built-in calibrator checks the accuracy of modulation readings. Isolated outputs are provided for the built-in modulation and carrier level alarms. Remote outputs are provided for all modulation indications as well as the carrier level.

FEATURES

Separate 100% negative and 125% positive peak modulation indicators

Peak indicator, modulation range from 40% to 130%, switchable polarity

All peak indicators independent of carrier level

Semi-peak-reading modulation meter responds accurately to short duration program peaks

Built-in Carrier Level (Loss) and Modulation Level Alarms, both with dry relay contact outputs

Built-in Modulation Calibration check

Linear-phase detector filter provides accurate modulation indications without overshoot

Switchable NRSC audio de-emphasis

SPECIFICATIONS

RF Frequency Range              260 kHz to 50 MHz

RF Sensitivity 			5 Vrms to 10 Vrms

RF Input Impedance 		1000 ohms std. (50 ohms opt.)

Modulation Meter Range 	        0 to 133% (switchable to either
                                           positive or negative modulation)

Fixed indicators		-100%, +125%

Adjustable peak indicator	range: 40% to 130%

Modulation Accuracy		ą 2%

Envelope Pulse Response		Overshoot <1%

Modulation Level Alarm		Adjustable threshold, fixed
					timeout (-15 seconds)
Carrier Level Deviation
	Meter Range		ą 30%

Carrier Level (Loss) Alarm	Alarms with a 30% drop from
					nominal carrier level	

Audio Monitoring Output		+10 dBu (2.45 Vrms), 600 ohm,
					active-balanced
Audio Test Output 
	(proof-of-performance)	5 Vrms, rear-panel BNC connector

Auxiliary Detector Output	5 Vrms

Audio Response			+0.0 dB/-0.5 dB, 20 Hz to 15 kHz
					(detector response -3 dB at 50 kHz)

Harmonic Distortion		0.25% maximum at 99% modulation

Signal-to-Noise Ratio		>80 dB (de-emphasis out)

Remote Outputs:
	Adjustable, +125%, -100% peak modulation
	indicators; auxiliary detector, carrier reference,
	remote modulation meter, remote carrier
	level meter, modulation level alarm &
	carrier level (loss) alarm

Operating Temperature		0°C to +50°C

Power Consumption		6 watts, 100-240 V, 50-60 Hz

Dimensions			5ź" H ´ 19" W ´ 7" D

Shipping Weight			10 pounds (4.5 kg)