Lectrosonics HMa Wideband UHF Plug-On Transmitter

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The Lectrosonics HMa is a unique plug-on transmitter design that will ideally match any microphone or line level source via a standard XLR connector. Phantom power is selectable at 5, 15 and 48 volts, or can be turned off for use with dynamic microphones and line level signal sources.

The design includes a wide tuning range of up to 76 MHz, with tuning steps in increments of 100 kHz or 25 kHz for up to 3072 frequencies. The tuning range covers three standard 25.6 MHz Lectrosonics frequency bands. Each of the standard bands includes 256 different pilot tone frequencies for compatibility with all Digital Hybrid Wireless receivers.

DSP compatibility modes are also included to work with legacy Lectrosonics analog wireless microphone receivers and IFB receivers, as well as some receivers from other manufacturers.

The transmitter is powered by two AA batteries, with status indicated by a multi-color LED. A USB port is provided for firmware updates. An IR (infrared) port is also included to simplify setup with IR enabled receivers.

The input amplifier uses an ultra low noise op-amp for quiet operation. It is gain controlled with a wide range dual envelope limiter, providing over 30 dB of headroom above full modulation. A 24-bit A-D converter digitizes the audio, then filters supersonic noise above 21 kHz. The resulting signal is encoded with a proprietary algorithm to produce an analog data signal for RF transmission. The underlying RF link is an optimized FM system with ± 75 kHz wide deviation for a high signal to noise ratio.

The antenna is formed between the machined aluminum housing of the transmitter and the attached microphone or cable. It functions as a dipole radiator when attached to a hand-held microphone and somewhat like a ground plane antenna when connected with a cable or plugged directly into a mixer. The conical shaped collar on the input coupler is made of DuPont™ Delrin® to improve the ERP of the antenna in the uppermost frequency bands.

The battery compartment door is hinged to the housing and remains attached to the transmitter when opened. It securely latches in place and applies pressure to the batteries when closed. The two AA batteries are connected in series through a conductive plate on the door.

Setup and adjustments are made with the control panel membrane switches and LCD. The transmitter can be powered up without the transmitter output enabled to allow frequency adjustments without causing interference to other wireless systems nearby. The switches can also be bypassed to prevent accidental changes. Dual color LEDs indicate audio input level and the power LED changes color under low battery conditions.

Lectrosonics HMa - Features:

• Accepts microphone or line level signals
• Selectable 5, 15, 48 volt phantom power
• 76 MHz tuning range in 100 kHz or 25 kHz steps for up to 3072 frequencies
• Selectable 50/100 mW output power
• Adjustable low frequency roll-off
• Powered by two AA batteries
• USB port for firmware updates
• IR (infrared) port for fast setup
• Solid machined aluminum housing

CONSUMER ALERT: This particular wireless microphone device operates in portions of the 617-652 MHz or 663-698 MHz frequencies. Beginning in 2017, these frequencies are being transitioned by the Federal Communications Commission (FCC) to the 600 MHz service to meet increasing demand for wireless broadband services. Users of this device must cease operating on these frequencies no later than July 13, 2020. In addition, users of this device may be required to cease operations earlier than that date if their operations could cause harmful interference to a 600 MHz service licensee’s wireless operations on these frequencies. For more information, visit the FCC's wireless microphone website or call the FCC at 1-888-CALL-FCC (TTY: 1-888-TELL-FCC).

• Operating Frequencies:
  • Block A1: 470.100 to 537.575
  • Block B1: 537.600 to 614.375
  • 941 Band (US Only):
    • 941.525 to 951.975 MHz
    • 952.875 to 956.225 MHz
    • 956.475 to 959.825 MHz
• Frequency Selection Steps: Selectable; 100 kHz or 25 kHz
• RF Power Output: Selectable at 50 or 100 mW
• Pilot Tone: 25 to 32 kHz frequency (Digital Hybrid mode); 5 kHz deviation (941 Band: 3.5 kHz deviation)
• Frequency Stability: ± 0.002%
• Deviation: ± 50 kHz (max in Digital Hybrid mode)
• Spurious Radiation: 60 dB below carrier
• Equivalent Input Noise: -125 dBV (A-weighted)
• Input level: Nominal 2 mV to 300 mV, before limiting; Greater than 1V maximum, with limiting
• Input Impedance: 1K Ohm (941 Band: 300 Ohms)
• Input limiter: Dual envelope "soft" limiter; greater than 30 dB range
• Gain Control Range: 55 dB; panel-mounted membrane switches
• Modulation Indicators: Dual bi-color LEDs indicate modulation of -20, -10, 0 and +10 dB referenced to full modulation
• Audio Performance, Overall System:
  • Frequency Response: 35 Hz to 20 kHz (± 1 dB)
  • Low Frequency Roll-Off: Adjustable for -3 dB @30, 50 and 70 Hz
  • THD: 0.2% (typ. 100 Hz to 20 kHz)
  • SNR @ Receiver Output:

    SmartNR	No Limiting	With Limiting
    OFF	103.5	108.0
    NORMAL	107	111.5
    FULL	108.5	113

    ^{Note: The dual envelope "soft" limiter provides exceptionally good handling of transients using variable attack and release time constants. Once activated, the limiter compresses 30+ dB of transmitter input range into 4.5 dB of receiver output range, thus reducing the measured figure for SNR without limiting by 4.5 dB.}
  • Input Dynamic Range: 125 dB (with full Tx limiting)
• Controls & Indicators:
  • Power/Phantom "ON-OFF"
  • Phantom voltage selector
  • Audio input gain
  • LCD w/ membrane switches
  • LED audio level indicators
• Audio Input Jack: Standard 3-pin XLR (female)
• Phantom Power: 5V @ 18 mA max., 15V @ 15 mA max. and 48 V @ 4 mA max., plus "OFF"
• USB Port: Used for firmware updates
• IR (Infrafed) Port: For quick setup by transferring settings from an IR enabled receiver
• Antenna: Housing and attached microphone form the antenna
• Battery: (2) 1.5 Volt AA alkaline
• Battery Life (Duracell Quantum):
  • AA alkaline; No Phantom Power: 5h 0m (tested with a dynamic microphone)
  • AA alkaline; 48V Phantom Power: 3h 30m (tested with a Sanken CS1 for a phantom-powered microphone)
• Dimensions: 4.25 x 1.62 x 1.38 in
• Weight: 7.5 oz | 211 g, with AA batteries