. QST . ed to or removed from the carantenna. It might be pointed out at this time that inany mobile installation where it is desired to usethe existing auto antenna on the converter, thisloading-coil arrangement can be used to advan-tage. On 40 meters and 20 meters, signals whichare unreadable using the standard auto antennabecome S9-plus when the extension is attachedand the proper loading coil plugged in. In ourcase, since the portable transmitter has a verylow-power output, separate loading coils weremade for each band in the interest of highestpossible efficiency. However, if the antenna
. QST . ed to or removed from the carantenna. It might be pointed out at this time that inany mobile installation where it is desired to usethe existing auto antenna on the converter, thisloading-coil arrangement can be used to advan-tage. On 40 meters and 20 meters, signals whichare unreadable using the standard auto antennabecome S9-plus when the extension is attachedand the proper loading coil plugged in. In ourcase, since the portable transmitter has a verylow-power output, separate loading coils weremade for each band in the interest of highestpossible efficiency. However, if the antenna wereto be used onh for receiving, the coil could bemade sufficiently large for use on the lowest-frequency band to be used, and tapped down forthe higher-frequency bands. Construction The construction of the center insulated sectionis shown in the drawing and photographs. It wasmade entirely from readily available parts, since The miniature mobile an-tenna with the loading coil inplace. September 1955 33. The center loading section connected to the , with the 40-meter coil in place. At the risk ofsomewhat lower efficiency, this single coil could betapped for use on the higher-frequency bands. we did not have tools or materials to do anymachining of connectors, tapping of polystyrene,etc. Undoubtedly, anyone with proper equipmentcould produce a better center section from amechanical standpoint. The bottom section of ordinary automobile an-tennas is approximately 5^6-inch in diameter, andmakes a fairly close fit into the ^-inch end ofthe reducer fitting. The outside diameter of theJ^-inch end of the fittings is smaller, thus pro-viding a larger shoulder to bear against the endplate when the retaining nut is tightened. In normal use of the copper-tubing fittings, thenut is tightened until the copper compression ringis compressed tightly against the tubing, thusproducing a leakproof seal. In our apphcation,the ring cannot be compressed enough becausethe antenna tubing is
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
