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BK Radios MX-921 Rack Mount Repeater VHF UHF

BK Radio SMX921 Repeater

Low Current consumption P25 Digital Repeater

Call for price and options 541-621-4588

BK radio SMX Repeater
The S and SD Series, low current Repeater and Base Station solutions, are designed from the ground up for the absolute lowest power consumption and features the lowest current draw of any professional high performance Repeater/Base Station on the market today. Advanced circuit design and optimization is demonstrated by the very high level of RF performance achieved while maintaining very low power consumption levels. The S & SD set a new industry benchmark by avoiding dated techniques that try to save power wasted by constantly duty cycling the receiver on and off or degrading the RF performance to unacceptable levels. The S & SD do not sacrifice any of these critical requirements and achieves a level of performance that competing products can provide at any power consumption level. Available as a Base Station or Repeater, in Analog Conventional (SMX) or P25 Digital (SDMX) (with LZAST92 P25 Option).


Very Low current consumption
No need for receiver duty cycling
System Interface
Fully Programmable / Configurable via PC or serial device
Remote controllable Multi tone CTCSS community decoder
100% full power duty cycle
5 Tone signaling
High Accuracy Real Time Clock.
Multi staged TX VF processing with triple limiters
Flash Firmware Upgrade Capable
Battery backup system option
Built In Test Equipment (B.I.T.E.) and remote diagnostics
Broad Band High Efficiency LDMOS PA module
RX & TX Switching BW covers full sub band
Fast Serial Data Interface
Full Digital alignment and calibration
Field interchangeable PA module needs no re-alignment
Pre calibrated power and deviation alignment. Digital value
Low RFI and EMI emission design
Controlled TX RF envelope
DTMF decoder
DTMF Remote control
Latest technology, full SMD
Advanced and optimized RF design
High performance 16 bit Flash processor
Programmable 12.5/25kHz channel spacing
Configurable Function Front Panel LEDs
Low current LEDs with digital intensity control
Simple and fast disassembly for service
Precision internal shielding system
Minimal technician adjustments for future maintenance
Design spec –40 to 70 degrees C
Low aging oscillators
Universal microphone input circuit
Minimal interconnections
Options can be easily retrofitted
Minimal mechanical adjustments
Front end RX filter never needs realignment
Built in TX modulation alignment audio oscillator
Built in auto alignment software guides technician
Fast and simple disassembly
Built on proven technology
Configuration password protected
Virtual elimination of internal wiring
Elimination of helical filters, quadrature coils, MCF matching and trim potentiometers
System independent, no additional software program required


P25 Repeater Option Board
Transparent Mode:
Repeats Mixed Mode, P25 Digital and Analog transmissions.
Automatically switch to P25 mode on reception of P25 carrier.
Passes P25 NAC unchanged.
Passes P25 private call and group call.
Passes P25 clear or encrypted.
Front panel indicators show P25 status.
Benefits of Digital Audio Performance.
Design based around proven architecture.

Additional Options
Desk Mic/Palm Mic
Internal Simplex relay
Virtual PC Console including:
Solar panel and battery power management system option board.
Universal system interface
SMX921 Specs

Frequency Bands
Band D3 148-174 MHz
Band L3  350-385 MHz
Band N2 400-435 MHz
Band O2 435-470 MHz
Band P2  450-485 MHz
Band Q   485-520 MHz

Synthesis Method    Non mixing PLL Fractional N synthesizer
Modulation    Direct FM two point method
Channel Spacing    Programmable 25kHz / 12.5 kHz
Synthesizer Step Size    6.25kHz or 5kHz auto select
100 front panel selectable, 255 PC software selectable
Supply Voltage    13.8 +/- 20%
Operating Temperature    -30 to +60C
Dimensions (W x D x H)    2RU Case, 325mm deep including fan
Standard LED indicators    Power, RX, TX, Tone, Alert, Repeater
Standard Switches    Two press button type
Standard Controls    Volume knob, Squelch screwdriver adjust.
Interface    Front panel Microphone accessory socket, speaker, rear connector DB25. Location for DB9 x 2, DB15, RJ45.
Weight    8kg.
Measured in accordance with TIA/EIA-603 Standards
Sensitivity    Better than -120dBm for 12dB SINAD, Typical -123dBm
Selectivity 135-520 MHz    More than 85dB for 25kHz adj channel, Typical 90dB more than 75dB for 12.5kHz adj channel
Audio Bandwidth    300 Hz to 3000Hz (+1,-3dB)
Image Freq Rejection    Better than 100dB
Spurious Response Immunity    Better than 82dB, Typical 84dB
Intermodulation Immunity    Better than 82dB (WB), 80dB (NB)
Blocking    Better than 100dB at +/- 1MHz point
Distortion    Less than 2% @ 60% deviation
S/N Ratio    Better than 50dB (WB)
Better than 44dB (NB)
Co-Channel Rejection    Better than 5dB
RF Switching Bandwidth    Equal to Sub band allocation
Receiver Front End BW    Equal to Sub band allocation
Receiver Audio Power    1 Watt
Measured in accordance with TIA/EIA-603 Standards
RF Power Output    1W to 50W variable,
0.1 to 2W* UHF PA opt (1W nominal)
Frequency Stability >300MHz
<300MHz    1.5PPM for –10 to 60C 2.5PPM for –30 to -10C
2.5PPM for –10 to 60C 5PPM for –30 to -10C
Audio Response    Flat within +1, -3dB across BW
Audio Bandwidth    300Hz to 3000Hz.
Modulation Distortion    Less than 2% @ 60% deviation
S/N Ratio    Better than 50dB (WB)Better than 44dB (NB)
Conducted Spurious Emissions    Better than -90dBc
Conducted Harmonic Emissions    Better than -90dBc
RF Switching Bandwidth    Full Sub band
RF Switching Bandwidth PA    Full Sub band
Duty Cycle    100% for 50W RF output
RF Rise Time    <50mS with VCO in cold standby