The Cushcraft R7000+ is a multi-band vertical antenna designed for amateur radio use, covering the 10, 12, 15, 17, 20, 30, 40, and 80-meter bands. This antenna, along with the R80 Add-On Kit, provides a comprehensive solution for radio enthusiasts seeking broad frequency coverage and reliable performance.
Function Description:
The R7000+ is an electrical conductor designed to radiate and receive radio frequency (RF) signals across multiple amateur bands. Its vertical configuration makes it suitable for various installation environments, and its broadbanded design minimizes the need for frequent tuning. The R80 Add-On Kit extends the antenna's capabilities to the 80-meter band, enhancing its versatility. The antenna utilizes a series of tubing sections, traps, and loading coils to achieve resonance on different frequencies. Counterpoise wires with anti-resonators are integrated to provide a proper match for 80-meter operation while preventing detuning on higher frequency bands. Guy ropes are essential for structural stability, especially given the antenna's height and wind load.
Important Technical Specifications:
- Frequency Coverage: 10, 12, 15, 17, 20, 30, 40, 80 meters.
- Gain: 3 dBi.
- Wavelength: Half-wave on each band.
- VSWR: 1.2:1 typical.
- 2:1 Bandwidth (KHz):
- 10m: 1700
- 12m: 100
- 15m: 450
- 17m: 100
- 20m: 250
- 30m: 100
- 40m: 100
- 80m: 70
- Power Rating: 1500 Watts.
- Radiation Angle: 16 degrees.
- Horizontal Radiation: 360 degrees.
- Height: 34.5 ft (10.5 m).
- Mast Size Range: 1-3/4 to 2-1/8 inches (4.4-5.4 cm).
- Wind Load: 2.5 ft² (0.23 m²) for the antenna, 1.5 ft² (0.13 m²) for guy ropes.
- Weight: 24 lbs (10.8 kg).
Usage Features:
The R7000+ is designed for ease of assembly and installation, though careful planning and adherence to instructions are crucial.
- Location: For optimal performance, the antenna should be mounted vertically and clear of surrounding objects like buildings, trees, power lines, and other metallic structures. It should not be attached to a ground radial system.
- Mounting: A rigid mast, 1-3/4 to 2-1/8 inches in diameter, is required. The mast must be securely mounted and self-supporting.
- Guying: The antenna must be guyed at two specific points using the supplied non-conductive, UV-stable 400 lb. tensile strength rope. Guy anchors are not supplied and must be installed securely. Guy ropes should not be over-tensioned.
- System Grounding: Direct grounding of the antenna mast is critical for protection against lightning strikes, static buildup, and high voltages. A good electrical connection to one or more ground rods using at least #10 AWG ground wire and non-corrosive hardware is recommended. A coaxial lightning arrestor should also be used.
- Adjustment/Tuning: Initial dimensions provided in Chart 1 usually allow proper operation. However, minor adjustments may be necessary depending on the installation environment. Adjustments must be made from the bottom of the antenna to the top, as settings at the top are affected by lower adjustments. The VSWR can be measured using a transceiver's SWR meter or a quality VSWR bridge. Adjustments involve lengthening or shortening specific tubing sections (Dimensions A, B, E, G) to shift the resonant frequency for each band. For example, lengthening Dimension A lowers the frequency of lowest VSWR on 10 and 12 meters, while shortening it raises the frequency.
- Counterpoise Wires: Three 20-foot long counterpoise wires with anti-resonators are attached to the antenna base. These wires are tied off to the guy points and should hang at an angle between 60 and 90 degrees relative to the mast, with their ends at least three feet above ground to minimize detuning. They should not be over-tightened or used as guy supports.
- RF on Feedline: If the antenna is close to the shack, RF on the feedline may occur. Solutions include lengthening the feedline, placing an RF ferrite bead on the coax, or winding the coax into a 10-turn coil (8 inches in diameter).
- Power Handling: The antenna has a power rating of 1500 Watts. Long periods (2 minutes or longer) of key-down operation, such as RTTY, at high power (over 1000 Watts) may damage the antenna.
- Safety: This antenna is an electrical conductor. Extreme caution must be exercised during installation to avoid contact with power lines, which can result in death or serious injury. Neither people nor pets should come into contact with any portion of the antenna, including the counterpoise rods, during operation due to potentially deadly voltages and currents. Long-term exposure to intense RF fields is not recommended.
Maintenance Features:
- Corrosion Protection: For installations in salty or corrosive environments, coating the antenna with a clear marine varnish or equivalent after final assembly and adjustment is recommended.
- Fastener Checks: After the antenna is completely adjusted, all fasteners should be checked to ensure they are tight.
- Guy Rope Inspection: Guy ropes should be checked occasionally for tightness and wear. They should be replaced every three to five years, depending on the environment. Polypropylene rope should not be used. Rope ends should be seared with an open flame to prevent fraying.
- Hardware Inspection: Periodically check for poor contact between the matching network and counterpoise rods, ensuring jumper strap terminals are free of corrosion and all hardware is secure.
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