Alpha Antenna Heavy Duty HF Base Vertical Antennas are designed for permanent outdoor installations covering the 80 through 10-meter Amateur bands. They operate as a full wavelength on 10 meters, half wavelength on 20 meters, and quarter wavelength on 40 meters. The antenna also supports 15 meters as it is the third harmonic of 40 meters. Additional tuning for resonance on 12 and 17 meters is achieved through the included matching network. This antenna system includes a grounded counterpoise element and ground stake, (no radials in addition to this are required). The combination of these components makes this antenna system function like an OCF (off-center fed) Dipole.

Key Features

• Heavy Duty Construction: Built for permanent outdoor installation.

• Multi-Band Capability: Covers 80 - 10 meters, including 12, 15, and 17 meters.

• Balanced Design: Includes grounded counterpoise and NVIS elements.

• Broadband Performance: Ideal for Amateur HF modes, Automatic Link Establishment (ALE), and Digital Spread Spectrum Encrypted modes.

• Easy Setup: Includes a heavy-duty mount, telescopic vertical element, matching network and a SO-239 feedline connector for a near 50-ohm match.

For optimal multiband HF vertical antenna performance, use the included elements that produce omnidirectional NVIS and directional DX. Combining the HF telescopic vertical aluminum element and the wire NVIS element enhances high band directional DX (in the opposite direction the wire NVIS element is run) and mainly omnidirectional low band NVIS. The NVIS element should slope away like a guy wire and not lay on the ground.

The grounded counterpoise wire runs in the opposite direction of the NVIS wire element, completing the balanced circuit at the antenna and providing a path to ground for common mode current and static buildup on the elements. Without grounding, there would be no path for current, resulting in an open circuit and less efficient system performance.

The ProMaster Heavy Duty HF Base Vertical Antenna is usable across a wide frequency range due to its design:)

1. Balanced RF Ground: Provided by the included 8ft. grounded counterpoise wire.

2. Radiating Elements: Utilizes a 17.5ft. vertical element and a 25ft. wire NVIS element.

3. Balun: Ensures balanced impedance of each element.

4. Feed-Point: Equipped with an SO-239 coaxial connector for a near 50-ohm match for your feedline and equipment.

This broadband design makes the ProMaster ideal for Amateur HF modes including CW, SSB (USB/LSB), AM, as well as ALE (automatic link establishment) or Digital Spread Spectrum Encrypted modes. An external antenna tuner may be required if the ProMaster is installed over poor ground, parallels a metal structure, is installed on a roof without adequate grounding, or is not placed in a clear area. The appropriate deployment angles for the grounded counterpoise and NVIS elements are between 90 and 180 degrees.

Included Accessories:

• Heavy-Duty Mount, U-Bolts and Hardware

• (17.50ft.) Telescopic Vertical Element - Self-supporting, with (6) 3ft. sections and (5) Stainless steel clamps

• (25ft.) Wire NVIS Element

• (8ft.) Grounded Counterpoise Wire & Ground Stake - (no radials in addition to this are required)

Specifications:

• Frequency Coverage: 80 to 10m (3.5 to 30MHz)

• Power Rating: 250W PEP SSB, 125W CW, or 25W Digital Modes.

• Feed-Point Connector: UHF SO-239 Female

• Construction Material: Heavy-duty Aluminum Mounting Plate and Hardware

Installation:

1. Use an optional tripod or place a 10ft. long 1-1/4in. O.D. metal mast (sold separately) 3 - 4ft. into the ground and install the included VERY heavy-duty mount and hardware onto the mast with the included U-Bolts. Alternatively, the system can be mounted on a wood post using four of your own wood bolts once the two included U-Bolts are removed.

2. Next, extend the telescoping element to an approximate length of 16ft. 4.8in. and secure each section with the stainless-steel clamps, where each section is not extended beyond the prior sections’ slits.

3. Then, attach the approximate 8ft. grounded counterpoise wire to the bottom bolt on the grey matching unit and run that wire to the included ground stake.

4. Finally, attach the approximate 25ft. wire NVIS element to the top bolt on the grey matching unit and run that wire with the included stake in the opposite direction of the grounded counterpoise before attaching your coaxial feedline to the SO-239 connector on the grey matching unit.