Grazioli HW10V 26-30Mhz 1/2

Main Features

1/2 λ vertical antenna fed at the base, tunable from 26 to 30 MHz by adjusting the whip length and fine-tuning at the base by means of a PTFE insulated high voltage variable capacitor (40 kV)

Extremely robust construction in AW6063-T66 aluminum alloy and CNC machined parts from solid stock.

Supplied with high-quality 304 and 316 stainless steel fasteners for long rust-free operating life.

High input power, up to 3 kW continuous All-mode.

Detailed assembly manual and serial number that identifies the production batch and construction data.

MATERIALS AND CONSTRUCTION

For our tubes, we have used the best antenna construction alloy available: AW6063-T66 is an alloy of Aluminium, Magnesium and Silicon that is hardened to a T-66 temper which gives the stylus exceptional resistance. It is shaped by extrusion and subsequent cold drawing. Our tubes are extremely accurate on both diameters and also on the wall thickness, ensuring a precise fit with less ‘play’ between the tubes.

The vertical whip consists of the following sections, starting from the bottom:

Anchor tube D.42×2

1st stage above the coil D.29×1.5

2nd stage D.25.5×1.5

3rd stage D.22×1.25

4th stage D.19×1,25

5th stage D.16×1,25

The insulator is made of D.38 white fibreglass with a wall thickness of 4.2 mm.

Electrical Data

Antenna Type:1/2 λ End Fed Vertical Dipole

Frequency Range: Tunable from 26 to 30 MHz (with Graph)

Impedance: 50Ω Unbalanced

Radiation Type: Omnidirectional

Polarization: Linear – Vertical

Gain: 0 dBd – 2,15 dBi

Bandwidth @SWR 2:1: ≥ 1,7 MHz a 28 MHz

SWR @resonance: ≤1.2:1 Typical ≤1.1:1

Max. Input Power: 3000 Watts continuos all mode

Feed system: high-Q air wound matching coil, DC-Ground

Input connector: 50Ω UHF female PTFE insulator, gold plated pin

Mechanical Data

Materials: Aluminnum Alloy AW6063-T66 hard drawn tube, Fiberglass, Brass, PTFE. All hardware are made of SS AISI-304 and 316

Wind surface area: 0,195m2

Wind load @ 130Km/h: 19Kgf 

Wind survival (no ice): 130 Km/h

Antenna Height: 5.94m 

Radials length: 5,38m (Half Wave)

Mounting mast bracket: ø 40-54 mm

Antenna Net weight: 3.1 Kg

Package dimensions: 14x14x145 cm

Weight in package: 4,3Kg

Why build an antenna capable of withstanding 3 kW of continuous power?

Because an antenna that accepts high power is a more efficient antenna. Otherwise, it would tend to heat up due to the Joule effect and dissipate a significant part of the applied RF power as heat, something that happens with most competing products but which, unfortunately, users cannot test for want of adequate equipment and instrumentation.

High-"Q" LC matching circuit

For this product, we have made a special parallel LC circuit to adapt the high impedance presented by this type of antenna when it is fed at the base.

The high-Q coil is generously sized, suspended in air, with widely spaced coils and no metal cores. The coaxial variable capacitor (similar to a Gamma Match) is located at the base next to the coil for easy tuning. Made with PTFE insulation, it can withstand extremely high voltages exceeding 40kV, and It is insensitive to ambient temperature, rain and humidity and does not heat up when subjected to high power.

During the development of the matching circuit, we had to carefully adjust both the inductance (L) and the capacitance (C) to obtain a truly efficient circuit that is reliable and trouble-free. All this results in high efficiency and the ability to handle RF power up to 3 kW continuous all-mode.

In addition, the coil is directly DC-grounded to significantly reduce atmospheric noise.

UHF Connector

The FE10V connector is not a commercial SO-239 type connector as most manufacturers use. The connector was designed and built directly by us, has a real impedance of 50 Ohms and can be used up to 500 MHz. The goal was to create a reliable connector capable of withstanding 5kW CW continuous at 30 MHz.

The body is made of CW614N nickel-plated brass, while the pin is plated in 24K gold to avoid oxidation and equipped with a 4-fin insulator that maintains its centering and elasticity, avoiding contact losses.

The insulating part is made of PTFE which is one of the best insulating materials due to its exceptional electrical (low dielectric constant, and reduced loss factor) and thermal (operating temperature from -100 ° to + 260 °) and is protected from a special elastomer hood that prevents water and humidity infiltration

The fixing bracket

Made of 2.5mm thick AISI304 stainless steel, it is fixed to the antenna tube by means of a clamp closure system, creating an extremely strong mechanical locking.

Fixing to the mast is made with AISI304 M6 V-Bolt and high type nuts to facilitate tightening.