THIS PRODUCT IS NO LONGER IN PRODUCTION
The Model 525 is our second-generation AM Mod-Monitor. It was specifically developed to give accurate AM readings with Hybrid Digital (IBOC) transmissions. The 525 is menu-driven with a peak-hold LCD display showing simultaneous positive and negative modulation, incoming RF level and asynchronous noise.
Measurement bandwidth extends to more than 10kHz, but a programmable low-pass audio filter can simulate the response of consumer radios or the effects of transmission bandwidth constraints. The 525 is supplied with an outdoor large aperture loop antenna.
Tunable from the front panel between 520kHz and 1720kHz in 10kHz steps; five station-memory pushbuttons.
Absolute-limit flashers (alarmed) are factory-calibrated at –100% and +125% carrier modulation. A second set of flashers may be set from the front panel in 1% increments between –70% and –100% and +70% and +140%.
Antenna: This 75-ohm (F) input is specifically intended for the large aperture loop antenna provided. Cable is not included, but up to 100 feet of common RG6 TV coax may be used
Direct: A high-level (BNC) input accepts a direct RF sample from the transmitter between 1V and 7V r.m.s.
Carrier amplitude demodulation extends from 20Hz to 10kHz, ±0.2dB. Modulation measurements are not affected by the user-selectable audio cutoff or NRSC de-emphasis.
Audio at the program line output and headphone jack may be menu-selected for “FLAT” response, which follows the full-bandwidth modulation measurement characteristic, or restricted in 1kHz steps between 10kHz and 2kHz (–3dB point) per the graph below.
A menu command turns NRSC ‘truncated’ 75μs de-emphasis on and off in the program audio and headphone outputs with any user-selected audio cutoff option.
Less than 0.5%THD at 100% carrier modulation
Typically better than 55dB below 100% modulation at an S9 carrier level with 10kHz audio bandwidth and NRSC de-emphasis selected.
The active-balanced (XLR) program audio output delivers +4dBm at 100% modulation. A front-panel headphone jack (1/4-inch TRS) also monitors the demodulated audio.
Front-panel indications and open-collector NPN transistor ‘tally’ outputs signal OVERMODULATION, CARRIER LOSS and PROGRAM AUDIO LOSS conditions.
105-130VAC and 210-260VAC; 50/60Hz; 20W
23” x 16” x 5” (2U); 12 lbs
584mm x 406mm x 127mm ; 5.4 kg