Rolls HR70 FM Broadcast Transmitter

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The Rolls HR70 is a digital display analog FM transmitter. Simply apply a signal to the XLR or RCA inputs of the HR70, select what frequency you would like to broadcast those signals on—87.5 to 108 MHz—and you are now sending signals via FM radio, assuming the antenna is connected properly. The HR70 also has a talk over circuit built in. Even though the HR70 is a micro power RF transmitter and requires no FCC licence, for it to function properly, good RF practices still apply. The wire antenna that is provided is set up for the middle of the band or about 92 MHz. For any transmitter to operate at its best, it must be earth grounded (think of it as "pushing" the signal against the earth). Range can vary widely, depending on grounding, antenna placement, obstructing building/walls, etc. Users report ranges of 150' or more down to 30' or so. Some experimenting may be required at your venue to find the optimum installation for your situation.

What is the maximum distance an FM transmitter can broadcast without a license? The quick answer is approximately 200' for an FM transmitter covered under Part 15 (read FCC Public Notice dated July 24, 1991). The full answer is much more complicated than that: 250 µV/meter @ 3 meters (also measured as 48 dBuV/m).

Rolls HR70 FM Broadcast Transmitter - Features:

• Simple way to broadcast signals over FM
• Max Power Output 4mW
• Antenna Jack: BNC
• Clean simple design
• All metal chassis
• Included DC power supply

• Frequency Response: 20 Hz - 12.5 kHz
• Input Impedance: 100K Ω Unbalanced, 600 Ω Balanced
• Indicators: Power LED and Clip LED
• Input/Output Jacks:
  • XLR balanced INPUT
  • RCA unbalanced input and output
• Power:
  • Rolls PS27s
  • 12 - 15 VDC 500mA
  • 5 x 1.2 mm DC Jack - Center Negative
• Antenna Jack: BNC connector
• Antenna Impedance: 75Ω
• Current: 150 mA
• Tuning Range: 87.5 - 108 MHz
• Dimensions (W x D x H): 6.75 x 4.25 x 1.6
• Weight: 1.5 lbs