The HR70 is a digital display analog FM transmitter. 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. Perfect for transmitting church services to a church parking lot!
Even though the HR70 is a micro power RF transmitter and requires no FCC license, 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 92MHz. For any transmitter to operate at its's best, it must be earth grounded. You can think of it sort of "pushing" the signal against the earth.
Range can vary widely, depending on grounding, antenna placement, obstructing building/walls, etc. In compliance with Part 15 of the FCC rules, these units are designed to top out at around 200 feet. However, we have had customers report ranges of up to 500 feet, and we have have also seen them only reach 50 feet. Antenna height and a clear channel are very important. Some experimenting may be required at your venue to find the optimum installation for your situation.
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Possible uses include: • Transmit your church service to the church parking lot in a drive-in situation.
• Use in Health/Fitness Clubs or Correctional Institutions as a sound transmitter where listening to multiple sources at the same time with privacy is required.
• Also perfect for ADA Compliance for ALS Assistive Listening System requirements in public spaces.
What is the maximum distance an FM transmitter can broadcast without a license? The quick answer is approximately 200 feet 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 V/meter @ 3 meters (also measured as 48 dBuV/m).
How to get the best range When attached vertically, the wire that is supplied with the HR70 can reach up to 150-200 feet. An inexpensive solution is to tape the supplied antenna wire to a wooden dowel which can easily be found in a hardware or craft store. Simply use a wooden base with a " hole drilled into it to match the dowel. With this easy setup, the supplied antenna has been shown to perform equal to or better than more expensive units.
If you would like something with better aesthetics, you could also put together a metal base with a fiberglass rod (must be non-metallic) and weatherproof tape. This
setup, however, would work the same as the wood dowel.
Having the wire straight and extended and at 6' to 10' height may give the best range. This type of antenna is called a wave dipole.
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Another tip for getting the best performance is to try different channels. Some frequencies will give better performance than others, even though both are vacant channels. It is best to try a few before you settle on one.
Using a longer BNC cable will let you put the transmitter further from the antenna. We have tested this arrangement outdoors to give a usable radius of 150-200 feet, but your setup can vary a lot.
Features • Frequency Response: 20 Hz - 12.5 kHz
• Antenna Impedance: 50/75 ohm
• Input Impedance: 100K? Unbalanced, 600? Balanced
• Indicators: Power LED and Clip LED
• Input/Output jacks: XLR balanced INPUT RCA unbalanced input and output
• Power: 12 - 15 VDC 500mA 5 x 1.2 mm DC Jack - Center Negative
• Tuning Range: 87.5 - 108 MHz
• Dimensions: 6.75"w x 4.25"d x 1.6"h
• Simple way to broadcast signals over FM
• Max Power Output 4mW 75 ohm
• Antenna Jack: normal female BNC
• Clean simple design
• All metal chassis
• Included DC power supply
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