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DL7RU Germany flag Germany

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40m Mono-Band Mobil-Antenna for Roof Rack installation

Loading coil is 25.2µH / 21 Turns / Diameter 85mm / Lenght 84mm / Q : 953 at 7.18 MHz / Wire is 2mm CuL (enamelled Copper) / self (parallel) resonant at 31.7 MHz / Winding pitch 4 mm / Coil-former 2mm Fiberglass / Isolator tube through the coil is a 20x3mm Fiberglass Tube. The Isolator tube also takes  the bending moment from the coil-former away

Matchbox:  LC-Low pass matching 7.9 Ohm to 50 Ohm / The Coaxial balun has 11 (or more) Turns Coax-cable RG316 (50 Ohm Teflon) on FT140-43 Core and is employed to keep RF off from the exterior of the feedline (~ -30 dB) / matching L (0.4µH) is Part of the Loading coil / matching C is 1020pF (470+330+220pF) to Ground / 100k 2 Watt Mox-Resistor to Ground for discharge static electricity

Two Antenna groundwires (6 mm2, red) are connected to the upper screws of the trunk door lifters (Plug contact)

IC-7000 Controlling Unit clips on the grid of the freshair exhaust (with 3cm distance)

Antenna foot is made from a Boat stanchion base 25mm / a short piece of 23.5 x 1.5mm Aluminum tube is glued in with UHU-Endfest-300 Epoxy cement / Ground base is a part of a 20mm thick Acrylic board

Icom IC-7000 /  A Step-Up Converter (grey housing) gives me a regulated 13.8 Volt DC output for the Transceiver even if the Battery voltage drops down to 10.5 Volts / Battery is 12V/60Ah / They are no connections to the Car (wiring) except the Tuner grounding at the trunk door

Antenna roof rack is made by 19.5x19.5x1.5mm Aluminum square tube

All worm clamps are stainless steel / The U-Bolts are home made and bended from 6mm stainless steel threaded rods

Antenna Dates: Length above the Coil 123 cm / Lenght overall (from the bottom off the acrylicboard to the top) 155 cm / Radiating-Element is a Aluminum tube 23.5x1.5mm ( 100cm), upper adjustable Tuningelement (30cm) is 19.5x1.5mm / Input Impedance (jX=0) 7.9 Ohm at 7.061MHz / SWR with Matchbox at resonance point 1:1.02 / SWR 1:2 Bandwidth 27kHz / Upper end of the Antenna above Earth-Ground: 323 cm / 1mm in length variation gives 2 kHz in Frequency variation / calculated Antenna efficiency (with formula from DL9AH) ~ 78%

All Aluminum-Elements are from the DIY-Market see http://products.alfer.com/Produkte/Eisenwaren/combitech-System-Basis/System-Profile-Aluminium/Rundrohr.html

This Antenna considered the wide experiences of Arno Weidemann (DL9AH) see www.dl9ah.de

Vy 73 Andy DL7RU   2014.07.31 

DARC-DOK: D01   -  e-mail: DL7RU@darc.de

This is the 80m Version / Overall hight 390 cm

2007  DK8NC

1341865 Last modified: 2014-10-12 17:37:08, 4541 bytes

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