July 2016 - AX CB Radio Club | Alpha Xray CB Club Global

Build a CB 11 metre 27 Mhz No Capacitor DDRR AntennaQuarter Wave Vertical Performance but LOW Noise (DIY in 30 minutes)Below is a shot of the original Mag wheel I had my 9 foot Whip on which is clamped to the iron roof and quarter wave whip now removed and the RG58 Coax fly lead PL259 is reconnected into the new CQDX11.com Design DDRR antenna. The DDRR is just an old piece of copper cable 20cm dia. bent in a wobbly circle.This is the perfect STEALTH and Flat Iron Roof Antenna which has Low angle Mainly Vertical but some Horizontal Polarisation to help with DX contacts. IT HAS NO CAPACITOR so SIMPLE to BUILD!Also as the main radiator is at ground potential the ambient noise level is way down compared to the Quarter wave whip!The CQDX11 DDRR CB Radio Antenna is now booming across Australia on skip and proving to be much quieter receiving less noise than the 1/4 Wave 9′ Whip!I have also added some holes in the top of the upright insulators to thread a cable tie through to anchor the radiator to them although it is so heavy being solid copper strands that it did not move much in the wind. We just last night had 100 klm hr winds across the roof and I have no worries about the CQDX11 DDRR going anywhere!-1.1:1 SWR @ 56 Ohms impedance on 27.305 MHz – Prefered setup with Antenna Analyser or good SWR Meter in actual location.D – USE Copper/Aluminium Tube or Coax – Heliax or EVEN RG213 would work I think! (But lower band width, maybe five channels with low SWR)SP – 12 ” high L – 108″ long Copper Tube or Coax cableG – 8″ – 9″ gap from upright to radiator end. NO CAPACITOR!FP – 8 – 9″ tap from upright along radiator. TO BE TESTED for LOWEST SWR on center of most used channels!It looks like a joke but it WORKS like a 9′ S/S Quarter WaveWhip BUT with LOW NOISE!!Low angle Mainly Verticle but some Horizontal PolarisationPerfect STEALTH and Flat Iron Roof AntennaMMM Motor Mouth Maul uses one similar on top of his vehicle and pumps many thousands of watts on AM into it for fun I believe! DDRR CB radio Antenna DDRR CB radio Antenna DDRR CB radio Antenna DDRR CB radio Antenna DDRR CB radio Antenna ALSO would be good for Caravans and Motor Homes – Some Facebook chat:-Greg Campbell I should add that it is important to find the correct FP Feed Point of centre conductor of coax by trial and error with a good swr meter but preferably with a Antenna Analyser to be able to do it quickly with DDRR in positionON A METAL GROUND (Tin Roof or similar) The coax braid must usually be connected to ground at base of upright ground point also but can be moved if required although I have found it works best there unlike other designs that have a capacitor and usual ground directly below FP. This is a very simple construction as you can see by my images on the webpage and looks like there is no way it should work as well as it does! Warwick J Denton Might work on top of the caravan….i wonder Greg Campbell Warwick J Denton It will work brilliantly! As long as it is metal and not fibreglass and it is only 12 inches high off the roof!Warwick J Denton Our caravan is a custom build all aluminum roofGreg Campbell Perfect for it mate! It does act the same as a 9 foot whip but low noise – it does slightly favour the direction of the upright piece away from the ring so mount that at front in center of you roof to project signal forward if needed.Greg Campbell Has high ‘Q’ so diameter of tube/radiator affects bandwidth so 1 inch copper or aluminium tube covers about 10 channels or so with acceptable swr. Probably should ideally use antenna tuner to cover 40 channels. It probably can be a squared off half wave as well I believe if tried and tested. Here is another great Aussie Antenna development with much higher standards of construction:-Amazing VHF Loop – In development [HERE] is a 24 to 54Mhz loop.For CB, Marine and Amateur Bands like 6m –Specifications: 10mm Alloy Construction – UHDP/Polycarb insulator TBA5mm Alloy driver ring – Size 44cm in Diameter.

Build CB 11metre 27MHz DDRR Quarter Wave Vertical Performance LOW Noise

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Month: July 2016

Build CB 11metre 27MHz DDRR Quarter Wave Vertical Performance LOW Noise

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