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TPEE MOVEMENT DURING tflNOSTOF-M CAUSES PAIL TO »IDE UP ftMlJ DOwr* PAE VEHT. IHG OtMitiE TO AfiRAY

TAP5 ADJUSTED AlaOUT l\/A "UFN5 EACH SHJE Of L.I CENTER PCtNT

The interconnecting open-wire I me is referred to as a phasing line. To ensure that the two sections of the array, upper and lower, are driven in phase and receive equal-ampli-rude rt currents, the feedpoint for the system should be located at the center of the open-wire phasing line, positioned a quarter wavelength away from the apex feedpoint of each vee section.

To the center feedpoint of the phasing line, connect another identical open-wire line but only one quarter-wavelength long. This quarter-wavelength line plus the quarter wavelength of line from the apex feedpoint of each vee sect ion down to the phasing line feedpoint will be equal to a distance of one half a wavelength and will cause the open end of the second quarter-wavelength line to appear as a highimpedence point. To feed a high-imped-a nee point on a line, you need a parallel-resonant tuned circuit. Such a circuit is useful for resonating the system and for matching the feedpoint to a 52-Ohm coaxial cable transmission line back to the transmitter.

Vee Beam Adjustments

The vee array, singly, stacked, or excited in quadrature, is virtually foolproof.. If you follow the dimensions and instructions given here the array won't fail to perform with good results. For maximum performance, all dimensions and adjustments should be made as accurately as possible.

The exact leg lengths arc not extremely criiieal for a given frequency; the exact lenglhs specified here have been pruned to allow you to use the array over a bandw kith of about 200 kHz without having to retune the coupling circuit at the antenna or change the loading at the transmitter. The longer the leg lengths, the less critical the adjust-

ments w ith respect to a change in frequency Once the array has been installed, connect the two output terminals of the 4:1 tmpedence ratio toroidal balun transformer at points about one or two turns each side of the LI

WlH SECTIONS ABOUT 45 Jt center point, Connect an swr (reflected power) meter in series with the 52-Ohm line and the coaxial input terminal of the balun iTest Point A in Fig, 4). Set the meter selector switch on F (forward), and turn the indicator sensitivity control all the way off From the transmitter, apply an unmodulated carrier signal of about 5 Watts or less, and of the correct frequency, to the 52-Ohm line. Adjust the swr meter sensitivity control until the indicator pointer reads exactly full-scale forward. Now, throw the meter selector switch to indicate reflected power (Ri Quickly rotate C\ for the lowest meter indication rnuH" or "dip"). If you can I bring the indicator pointer to zero, move the balun tap connections away from or closer in the center of LL

When the tap connections arc correct and the indicator pointer reads zero by adjustment Of CI, the 52-Ohm line wit I be "matched'* through the balun to the 208-Ohm balanced feed points on LK At the transmitter, the line should "match" the transmitter 50-0hrtl output impudence without having to use an antenna "tuner/h The transmitter output circuit should load normally to the rated output power level

Fit Id Strength Adjustments

To adjust the array for maximum gain (field strength). : used a portable. baitery-op-erated solid-state short-wave receiver The General Electric Model 7-2990A or equivalent is ideal for this purpose, i heGfc! receiver is equipped with a digital-readout frequency

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