Personal FM System; 72 - 76 Mhz; 1 PPA T46 transmi tter

The Williams AV PFM PRO RCH is a rechargeable personal FM listening system built for situations where background noise or distance makes speech difficult to follow. Intended for classrooms, work environments, or home use, it operates across 17 selectable channels from 72.1 to 75.9 MHz and is specified for a range of up to 150 ft (45 m). The system centers on one PPA T46 transmitter, combining FM transmission with visible status feedback and direct control over microphone and auxiliary audio.

Ideal Use Cases

The PFM PRO RCH is designed for classrooms where distance and surrounding noise can interfere with clear audio, as well as work environments that require sound to reach an individual listener. It can also support personal listening applications at home. The transmitter is compatible with PFM R31, PFM R32, PFM R33, PFM R36, PPA R35, PPA R37, PPA R35-8, and PPA R1600 receivers, allowing it to integrate with a range of listed Williams AV receiver models.

Why Choose This Model

The PPA T46 provides 17-channel operation with a menu-selectable choice between 17-channel and 8-channel modes. Its OLED presents the selected channel or frequency, microphone audio level, auxiliary input audio level, battery status, microphone mute status, channel lock, and dual-preset mode. Adjustable inputs help accommodate different audio sources: the 3.5 mm mono microphone input has electret microphone bias and a 25 dB gain range, while the 2.5 mm stereo auxiliary input offers a 60 dB gain range. Selectable 1:1 or 2:1 audio compression provides another way to configure the transmitted signal.

Installation and Integration

Connect an electret microphone through the transmitter’s 3.5 mm mono microphone input or attach an auxiliary source through the 2.5 mm stereo input. The transmit antenna is integrated with the microphone cord, while the receiving antenna is integrated with the connected earphone or headphone cord. Select the required operating channel from the transmitter menu and configure the compatible receiver for the same frequency. Up, Down, and Menu buttons provide access to transmitter settings. The main push button turns the unit on or off when held for three seconds and toggles microphone mute when pressed and released. A battery-type switch behind the battery-compartment door selects alkaline or NiMH operation.

Performance Highlights

The system’s operating frequencies span 72.1 through 75.9 MHz, with a specified transmission range of 150 ft (45 m). FM modulation uses plus or minus 75 kHz peak deviation, while frequency stability is rated at ±0.005% using a synthesized, crystal-referenced PLL design. RF output is specified at 80 mV/m at 3 m, the maximum allowed by FCC rules. Published receiver-side specifications include a maximum peak audio output of 35 mW into 16 ohms, a 3.5 mm stereo/mono output jack, and automatic sleep mode after approximately six minutes without an RF signal.

What Makes It Different

The T46 combines transmission controls and signal monitoring in a single OLED interface. Operators can review microphone and auxiliary levels before adjusting volume, auxiliary input, compression, channel mode, screen timeout, or screen brightness. The menu also provides a restore-default-settings function. A green power LED flashes when the battery is low. The enclosure uses shatter-resistant PC/ABS plastic with a textured, scratch-resistant aluminum faceplate. Listed approvals and directives include FCC, Industry Canada, RoHS, and WEEE. Warranty coverage is identified as a Lifetime PLUS Limited Warranty, with 90 days on most accessories.

Final Assessment

For classroom, workplace, or home applications that need personal audio beyond direct speaking distance, the PFM PRO RCH provides a defined FM signal path, 17 selectable channels, and up to 150 ft of operating range. Its OLED supervision, independently adjustable microphone and auxiliary inputs, selectable compression, AA alkaline or NiMH battery support, and compatibility with multiple Williams AV receivers make it a configurable option for overcoming noise and distant sound.