Grazioli - Vertical multiband 1/4 λ GP MV6

Main Features
Now supplied with original FAIR-RITE FT240-43 ferrite toroid Made in USA

Vertical multiband 1/4 λ Ground Plane base-fed antenna for the following HAM bands: 20, 17, 15 12, 10 and 6m.

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.

For our tubes, we used the best material that can be used for antenna construction; it is the Aluminum, Magnesium and Silicon alloy named AW6063-T66, hardened to the T-66 state. It gives the stylus exceptional strength, which is made by extrusion and then cold-drawn.
Of extremely robust construction, the central stylus uses 42x2mm diameter tubes at the base and 19x1.25mm diameter at the tip, while the side stubs and ground plane radials are made of 13 and 10mm diameter telescopic tubes;
The ground plane is formed by 4 horizontal radials of approximately 2.7m in length, and the vertical stubs are held in place by 3 crossbars, the first connected to the base of the stylus is made of CNC-machined rectangular-section aluminium tubing, and the other 2 of thermoplastic material, one with 4 arms in the middle part, and one with 2 arms in the upper part.
All hardware is made of stainless steel, the tubes are secured with robust, quality stainless steel AISl-316 clamps, brackets, hardware, and U-bolt and V-bolt U-bolts are made of AISl-304 stainless steel.

A high-performance multiband

The stylus consists of a central radiator for the lower 20m band flanked by 4 side stubs resonating on the higher 17,15,12,10 + VHF 6m bands. The side stubs are 1/4 wavelength without traps that would reduce their efficiency. The antenna is fed directly without the use of impedance adapters or transformers, which would introduce losses and limit the applicable power, and is equipped with a high-impedance inductance that creates a DC short circuit, grounding any disturbances caused by atmospheric events and/or electrostatic discharges.
Calibration is done by adjusting the telescoping parts of the stubs and the central stylus, each frequency is independent and does not affect the other bands, except for the 17m band, which also determines the resonance of the 6m band: We recommend the use of a graphic antenna analyser such as Rig-Expert or Nano VNA, which makes calibration much easier.

NOTE:
If used in very windy areas, bracing with non-conductive cables using the supplied fifth wheel is recommended.
We recommend the use of a CHOKE (not supplied) to be installed immediately below the connector to avoid possible RF feedback on the coax.
The RF Choke for attenuating common mode currents

Now supplied with the MV6 is an original FAIR-RITE Made in the USA FT240-43 ferrite toroid for “Home Made” construction of your high-performance Choke. This arrangement allows you to significantly attenuate common mode currents in the HF band (1.8-30MHz), which could reduce the performance of your antenna.

Material not supplied at customer's expense for fabrication:
- No.2 PL259 connectors suitable for the type of cable you intend to use.
- (1 PL259 + 1 SO239 in case of using plastic protection box).
- Approximately 1.2m of good quality coaxial cable, such as RG58 for continuous powers up to 300 Watt AWG @ 30MHz, or RG142BU in Teflon for continuous powers up to 1500 Watt AWG @ 30MHz.

We absolutely discourage the use of cables with FOAM foam-type dielectric (white spongy dielectric) because they cannot be wrapped around the toroid without compromising its electrical characteristics.
DOWNLOAD CONSTRUCTION INSTRUCTIONS
MV6
UHF connector

The MV6 antenna connector is not the commercial SO-239 type used by most manufacturers. Our connector is designed and built directly by ourselves; it has a true 50 Ohm characteristic impedance and is rated up to 500 MHz. We have created a reliable connector capable of withstanding 5 kW of continuous RF power at 30 MHz and greater than 3 kW at 50 MHz.

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

The insulating material is PTFE, one of the best insulators due to its exceptional electrical and thermal properties (low dielectric constant and reduced loss factor, operating temperature from -100 to +260 °C). The assembly is protected by a special elastomer hood that prevents water and humidity infiltration.
The fixing bracket


Is made of 2.5 mm-thick AISI 304 stainless steel and is attached to the antenna tube by means of a clamping system, creating an extremely robust mechanical lock.

The mast coupler is consists of an M6 V-Bolt in AISI 304 steel and column nuts for easy, secure tightening.

Electrical Data         Mechanical Data
Type     Ground Plane 1/4 λ with parallel stubs     Materials     Aluminum Alloy AW6063-T66 hard drawn tube, Fiberglass, Brass, PTFE.
All hardware are made of SS AISI-304 and 316
Frequency Range     HF 20, 17, 15, 12, 10 + VHF 6m     Wind surface area     0,4m2
Impedance     50Ω Unbalanced     Wind survival (no ice)     130 km/h (braked)
Radiation Type     Omnidirectional     Total Height     6,75m
Polarization     Linear – Vertical     Stylus length     6,2m
Gain     0 dBd – 2,15 dBi     Radial length     2,7m
Bandwidth with SWR 2     ≥ 20, 17, 15, 12 full band 10&6m > 1.5:1     Mounting mast bracket     ø 40-54 mm
SWR @resonance     ≤1.5:1 (Typical)     Antenna Net weight     7,8 Kg
Max. Input Power     3000 Watts continuos all mode     Package dimensions     14x14x145 cm
Feed system     Direct - connected to DC ground     Weight in pack     9,2 Kg
Input connector     UHF female - PTFE insulator, gold-plated centre pin