//************************************************************************** // Display window with the G3OGR document. //************************************************************************** function View_G3OGR( ) { G3OGR=window.open('','G3OGR_Win', 'menubar=yes,resizable=yes,scrollbars=yes,status=yes,width=750,height=650'); with (G3OGR.document) { write("\n") write("\n") write("EASY END FEED Z-MATCH By G3OGR\n") write("\n") write("\n\n") write("\n\n") write("\n") write(" \n") write(" \n") write(" \n") write(" \n") write(" \n") write("
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Javascript Electronic Notebook
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\n") write(" by G3OGR

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This is an article written by G3OGR and orignally\n") write(" published in the January 1972 issue of 73 Magazine. I do not have any\n") write(" information, other then the authors call sign, because my copy had that\n") write(" information deleted. I tried to look up the call sign but came up with nothing.\n") write(" If anyone has more information about the author, I will gladly add it to the credits.\n") write(" You can send me email through my\n") write(" Contact Page.

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EASY
END FEED
Z-MATCH

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\n") write(" If we look for the quickest, easiest, cheapest way to put\n") write(" out a signal on any band from 80 to 10, we see that the answer is an end-fed wire. This has \n") write(" extremely variable characteristics in terms of radiation, depending on length, band, direction, \n") write(" etc. On any particular band it is generally about as good as a dipole, if similar in length \n") write(" to a dipole for that band. On lower frequencies it may be a quarter wavelength or less, \n") write(" while on higher frequencies it would be two half-waves, or more.

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The beauty of the end-fed wire is that in practice\n") write(" it can be any length. This means it is strung between the two best available supports,\n") write(" with one end (adequately insulated) decending into the shack. It may be vertical, sloping,\n") write(" horizontal, or a mixture of these, and i sprobably longer than about 20 ft, though it is\n") write(" unlikely to be over about 125-150 ft unless you are lucky with space.

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It's feed impedance will be a variable thing, according\n") write(" to frequency, length, and other factors. The usual transmitter or transceiver pi output\n") write(" tank is mostly intended to work into a load of about 50 to 75 Ohms. So inevitably, this\n") write(" and the end-fed wire will be incompatible on some bands.

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Z Match

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\n") write(" \n") write(" An impedance or Z-matching defice between transmitter \n") write(" and end-fed wire corrects matters so that all but extremely short wires will load the\n") write(" transmitter. Figure 1 is a simple but practical circuit. L is a robust tapped coil, \n") write(" and the variable capacitor is about 150 pF, wide spaced for other than low power.\n") write(" This was found satisfactory for any wire from 10 to 150 ft. With shorter wires arcing\n") write(" occurred. The longer wires naturally radiate better.

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This is a good opportunity to use a surplus inductor.\n") write(" The one actually used was wound for the job, however. It had 26 turns of 16-gage wire \n") write(" on a 2-1/2 in. diameter ceramic form, the winding taking up 3-1/2 in. Stout leads soldered\n") write(" on go to the tabs of a 12-way rotary switch (Fig. 2). The switch selects the following\n") write(" numbers of turns - 0 (coil shorted), 1, 2, 3, 5, 7, 9, 12, 16, 21, and 26 (whole coil).

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\n") write(" \n") write(" An swr indicator may be put in the coax from the\n") write(" transmitter to Z match. A good earth ground is helpful. Remember, there may be\n") write(" considerable rf on the antenna connection.

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The receiver or transceiver S-meter should give \n") write(" a guide to tuning. Begin with the capacitor at minimum, and no turns in circuit.\n") write(" Rotate the switch to bring up signals. When the best point is passed (too many turns)\n") write(" rotate the switch back one position, and peak the variable capacitor for best\n") write(" reception.

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Adjustments are somewhat similar for transmitting.\n") write(" If the TX pi output capacitor is at about a setting which would work into around \n") write(" 50-75 Ohm, rotating the capacitor with the correct number of turns in circuit\n") write(" will show a point where the system draw poer and can load the transmitter.

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It was found that with quite long wires, the\n") write(" variable needs little or no adjustment over a fair section of a band. But\n") write(" with short wires, it has to be retuned with other than small changes in frequency.

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...G3OGR

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\n") write("\n") write("\n") close() } // End of "with (G3OGR.document)" statement } //************************************************************************** // Display window with the G3OGR document. //************************************************************************** function View_MFJ16010( ) { MFJ16010=window.open('','MFJ16010_Win', 'menubar=yes,resizable=yes,scrollbars=yes,status=yes,width=850,height=650'); with (MFJ16010.document) { write("\n") write("\n") write("MFJ-16010 Random Wire Antenna Tuner\n") write("\n") write("\n\n") write("\n\n") write("\n") write(" \n") write(" \n") write(" \n") write(" \n") write(" \n") write("
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Javascript Electronic Notebook
\n") write(" \n") write(" MFJ-16010 Random Wire Antenna Tuner
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MFJ-16010 Random Wire Antenna Tuner

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\n") write(" Thank you for purchasing the MFJ-16010 Random Wire Antenna Tuner.

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GENERAL INFORMATION

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\n") write(" The MFJ-16010 is a variable L-network designed to match the low output\n") write(" impedance of your transmitter to the high impedance of a random wire (or vice\n") write(" versa). It will match almost any random length of wire to any transmitter from 160\n") write(" thru 10 meters. The transmitter may have an output RF power up to 200 watts. For\n") write(" best results, the random wire should be as long, high, and clear of surrounding\n") write(" objects as possible. Do not ground the random wire antenna.

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\n") write(" The connectors are labeled properly to match a transmitter to a higher\n") write(" impedance. This is the normal connection.

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\n") write(" To match impedances that are lower than your transmitter impedance (such as a\n") write(" mobile whip), simply interchange the normal transmitter and antenna\n") write(" connections to the MFJ-16010.

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\n") write(" Remember the MFJ-16010 is designed to match a single random wire and not a\n") write(" coaxial line, even though coaxial connectors are used for both antenna and\n") write(" transmitter connections (these connectors make it easy to interchange antenna\n") write(" and transmitter connections).

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\n") write(" A standard banana plug will fit nicely into the center of the S0-239 coaxial\n") write(" connector and can be used to connect the single random wire in lieu of a\n") write(" coaxial plug (PL-239).

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\n") write(" A standard coaxial cable having an impedance that matches your transmitter\n") write(" output impedance, should be used to connect your transmitter to the\n") write(" MFJ16010. Make sure the MFJ-16010 is well grounded to the transmitter.

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\n") write(" If you are using the MFJ-16010 to match a vertical or mobile whip, the tuner needs\n") write(" to be at the feed point of the antenna and not at the transmitter end of the\n") write(" coaxial transmission line.

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USING THE MFJ-16010

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\n") write(" To match high impedances, the transmitter connector of the MFJ-16010 should\n") write(" be connected to your transmitter or receiver and the random wire connected to\n") write(" the antenna connector. The Inductance switch of the MFJ16010 presents a\n") write(" minimum inductance when pointed straight up. Low inductance is for high\n") write(" frequency operation and high inductance is for low frequency operation. The\n") write(" capacitor is completely closed (maximum capacitance) when the control is\n") write(" pointed straight to the left. When tuning up your transmitter, it is best \n") write(" to use a SWR meter. Connect the MFJ-16010 as in figure A.

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\n") write(" Tune your transmitter for minimum SWR using the following procedure:\n") write("

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  1. \n") write(" For each position of the Inductance switch, rotate the Capacitance control\n") write(" for maximum noise.\n") write("
  2. \n") write(" Apply enough transmitter power to give adequate indication on your\n") write(" SWR meter. Do not apply full power while tuning for minimum SWR.\n") write("
  3. \n") write(" Turn the Inductance control for a drop in SWR.\n") write("
  4. \n") write(" Adjust the Capacitance control for minimum SWR.\n") write("
  5. \n") write(" If minimum SWR is not achieved, increase or decrease the Inductance\n") write(" control one position then adjust Capacitance until minimum SWR is\n") write(" achieved. If arcing between capacitor plates occurs, increase or\n") write(" decrease the Inductance control one position then adjust Capacitance\n") write(" control for minimum SWR.\n") write("
  6. \n") write(" After minimum SWR is obtained, full power up to 200 watts output may be\n") write(" applied to the MFJ-16010.\n") write("

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\n") write(" For receiving, repeat step 1 then adjust Capacitance control for maximum\n") write(" noise or signal strength.

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