W8YZ Balanced Multi-Band Wire Aerial

Schematic diagram of the W8YZ multiple band balanced non-resonant antenna with matching device.  The antenna is an inverted "V" constructed of # 8 AWG seven-strand wire with an overall length of 100 feet with each half extending 50 feet.  The apex is at 50 feet with the ends sloping to 20 feet at either side of center.  

Radio engineering theory and practice in commercial services takes advantage of the fact that an antenna does not need to be electrically resonant in order to operate efficiently.  The concept that an antenna must be resonant has arisen because the feed point of an inverted ”V” antenna is approximately 50 ohms which is easily to match to most transmitters.

 

The 450-Ohm balanced feeder is made of #8 AWG copper wire spaced 4.5 inches with custom made acrylic spacers.  Each attachment to the wire is bonded with a soldered tie wire.

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Balanced 450-Ohm feeder attaches to the tower and is routed around obstacles

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Balanced line feed-through is in Teflon tubing.  The brick and mortar is kept dry by a wide eave overhang and there is low loss in the sill plate and brick veneer wall.

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In English, what you see is an aerial coupler.  The function of this device is to “couple” the transmitter to the aerial; hence, it is an aerial coupler.  The input is routed though a Ten Tech "L" pad model 238 tuner to touch up the match on frequencies above 3 MC.

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This is the tuning condenser shown in the schematic and is, not to be confused with a noodle cutter.  Fully meshed, it has a capacity of 560 Micro Micro Farads

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This is one of several transformers shown in the schematic having a 12-turn secondary made of solid #10 AWG copper insulated with 1/16-inch Teflon tubing.  The primary is three turns of stranded #14 AWG machine tool wire that is driven from a 50-ohm unbalanced source.  The secondary current is 23 amperes when tuned to 1860 KHZ at 1500-watts carrier power.  This high current is caused by high circulating current.  The tuning condenser is across the secondary.  The core is #2 powered iron mix weighing about two pounds.

The toroidal core is #2 (red) powdered iron material 4.00-inch OD by 2.25-inch ID by 1.30- inch high.  It is Amidon part T400A-(#2).  The present cost is $24.00 plus shipping.

The Teflonâ-FEP tubing is 1/8-inch ID by 3/16-inch OD.  The FEP specification is more flexible than the less costly TFE specification.  Teflonâ has been found a good choice because of low dielectric loss the insulation on #10 AWG house wiring has so much dielectric loss that it is unsuitable and will melt at near full legal power.  A source for the tubing is Consolidated Plastics Item No. 10457LW which is listed at $35.48 per 25 foot coil.

The toroidal core is attached to a 1/4-inch thick piece of phenolic fiber plastic and had Amphenol plug in connectors to permit quickly changing to a core with a different turn ratio.  The primary is three turns #14 AWG machine tool wire.  There is very little circulating current in the primary but the secondary has a circulating current of 23 amperes in portions of the 160-meter band.

A single coupling transformer coil is sufficient for frequencies near 2 MC to above 8 MC.  It is advised to make the coupler so it matches es the lowest frequency of interest without a tuner in line.  The tuner works efficiently at frequencies above 3 MC and higher.

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The end insulator is made of 1/4-inch thick acrylic plastic

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