Johnson Viking Matchbox Antenna Coupler
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Viking Matchbox
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0
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Informacja

The Johnson Matchbox is an Antenna coupler designed for matching Antenna and transmission line impedances to a 52 ohm impedance within the amateur bands from 3.5 to 30 megacycles. The Matchbox also provides band switching and transfer of the coupler from Transmitter to Receiver and in addition mutes the Receiver and grounds the Receiver Antenna terminals during transmission. The Matchbox is capable of matching the 52 ohm coaxial output of a Transmitter into loads ranging from approximately 50 ohms to 1200 ohms for balanced lines, and 50 to 2000 ohms for unbalanced lines. Large amounts of reactance can be compensated for by the coupler, the amount depending upon the frequency, line or Antenna resistance. The Matchbox, or any coupler, installed at the Transmitter end of the transmission line cannot correct the standing wave on the transmission line. This standing wave is a matter of impedance match between the Antenna and the transmission line and may be eliminated in various ways described in Antenna and transmission line literature. The coupler circuit consists of a parallel resonant network utilizing an inductor with a coaxial wound coupling link, a dual tuning capacitor, and a dual differential matching capacitor as shown in Figure 1. Impedance matching for either balanced or unbalanced transmission lines and antennas is accomplished by the front panel controls of the two dual capacitors without resorting to the customary coil taps or link adjustments. Adjustment of the Matchbox must be accomplished by the use of a directional coupler, such as Johnson no. 250-37, The Matchbox tuned circuit provides additional harmonic attenuation of the Transmitter output by at least 15 db. The 52 ohm coaxial line between the Transmitter and coupler provides for the insertion of a low pass (TV1) filter such as the Johnson 250-20 for improved harmonic attenuation. A terminal is provided on the terminal board for the installation of an R. F. probe for use with an oscilloscope, modulation indicator The Kilowatt Matchboxes (part nos. 250-30 and 250-30-3) have a switching relay system designed for ,ffast make-slow break" operation allowing the final Amplifier plate voltage to be cut off before the Transmitter load is removed. The time of delay is fixed between . 15 and .25 of a second which is ample to allow the relay contacts to break without any arcing,

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Instrukcja obsługi
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Instrukcja obsługi
Strony:
11
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604.67 Kbytes (619177 Bytes)
Język:
english
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Ręczny ID:
2-0250-023
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Skanowany dokument, wszystko czytelne.
Data przesłania:
2014 03 01
MD5:
6e0506d16f60b0bc8e6d43dddcbc81c4
Pobrane:
1234