Hardware Description, Installation and Connections (FMBM)

Front & Rear Panel Descriptions

Front Panel

Front Panel
  • 2-Line, 16 Character LCD: Backlit display shows current readings and displays menu settings.
  • Up Button ˄: Increases headphone volume in Default mode and scrolls forward through configuration menu in Menu mode.
  • Down Button ˅: Decreases headphone volume in Default mode and scrolls backward through configuration menu in Menu mode.
  • Power LED: Indicates that unit is powered-up and operational.
  • Menu Button: Shifts to Menu mode when in Default mode and selects menu item when in Menu mode.
  • Alarm LED: Shows aggregate status of all alarms in FMBM.
  • Power Monitor Calibration: 10-turn potentiometer, allows calibration of back-panel RFLevel DC output. See this article.
  • Headphone Jack: 3.5 mm jack for standard stereo headphones.

Rear Panel & Screw-Terminal Pinout

The FMBM’s back panel has plug-in screw terminal connectors for the alarm relay outputs, the RF-Level and FM Deviation voltage outputs and for the balanced audio outputs. It also has the input connectors for the Antenna and High-Level RF inputs as well as the USB and 12Vdc power connectors. Model -02 has a multiplex input/output connector and an optional AES digital output.

FMBM-01 Rear Panel
FMBM-02 Rear Panel
  • Alarm, Monitor & Audio Outputs (see the FMBM Alarm Relay, Monitor and Analog Audio output pinouts images below for details)
  • Antenna Input*: Type F connector for low-level RF input from 75Ω antenna.
  • Ground Terminal: Chassis ground lug.
  • High-Level RF Input: Input for use with on-site directional couplers or other signal sampling devices that allow the FMBM to measure and monitor transmitter levels. Note that when using the high level input, nothing must be left connected to the low level (antenna) input and vice-versa because this could cause improper calibration. The corresponding RF Input selection must be made in the operating Menu.
  • 12Vdc Power Connector: Davicom standard XLR power connector. The corresponding female XLR connector is supplied with the FMBM’s accessories.
  • USB Communications (Type B) Connector: Connector for interface to Davicom units or to a PC.
  • AES Digital Output** (Mini XLR connector, Model -02 only): optional AES digital output with jumper selectable rates of 44.1 kHz, 48 kHz, 88.2 kHz and 96 kHz. The connector pinout is given below:

The recommended Mini XLR female connector for the AES Digital Output is a TA3FSH from Switchcraft Inc. This connector is not provided with the unit. See Appendix B for AES digital output option installation instructions.

  • MPX IN/OUT (BNC connector, Model -02 only): multiplex input/output (selectable from the on-screen menu). Can accept more than 1Vpp in input mode and provides up to 3Vpp in output mode.
  • MPX IN Level (Model -02 only): MPX In level adjust.

* Attention: To ensure correct operation, make sure the antenna is not located close to sources of RF interference.

** The option must be installed to have digital AES audio signals present on the rear panel mini XLR connector. The AES digital output option can be installed by the user at any time after the initial purchase (Ordering number: FM-AES)

FMBM-01 Alarm Relay, Monitor and Analog Audio output pinouts
FMBM-02 Alarm Relay, Monitor and Analog Audio output pinouts
  • Alarm Relay Outputs: The alarm relays are factory configured as normally open (NO), but can be changed to normally closed (NC) by setting internal jumpers. See this article for details on setting these jumpers.
  • RF PWR Monitor Output: This output produces a voltage that is proportional to the RF Power level at 0.5V/dB. Its level can be adjusted via the Power Monitor Calibration Menu item. See this article. NOTE: If the peak deviation exceeds 100 kHz, the RF PWR Monitor Output may be affected.
  • DEV. OUT (Modulation) Monitor Output: This output produces a voltage that is proportional to the FM Modulation (Deviation) at 33mV/kHz. It is factory set to produce 2.5V for 75 kHz of deviation.
  • Audio Outputs: Balanced audio outputs for Left and Right audio signals. Default level is +8dBu and is adjustable from 0 to +10dBu through the Audio Level Menu item. Adjusting the analog audio level will also adjust the digital audio level.

Cables, Connections and Accessories

Standard accessories include a USB cable, a 4-pin female XLR connector for 12Vdc power (+12V is on Pin 4 and Ground is on Pin 1) and plug-in screw-terminals for the Alarm Relay, Monitoring and Audio outputs.

Power Supply

The FMBM operates from any standard 12Vdc Power Supply, such as the Davicom ILPS5012N, that can source up to 1A.

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