MFJ MFJ-932 User Manual

MFJ-932 Mini Loop Tuner

Instruction & Technical Manual

INTRODUCTION & FEATURES

MFJ-932 MINI LOOP TUNERTM INTRODUCTION

The MFJ-932 Mini Loop Tuner

is a small, versatile, high -efficiency device that turns any wire loop into a high -efficiency multi-band transmitting loop antenna system designed for 50-ohm use at 20 Watts maximum input (all modes). It consists of two functional units:

• MFJ-932 Mini Loop Tuner

(Shown in Figure 1)

• Wire Loop(s) (not included)

Figure 1: MFJ-932 Mini Loop Tuner

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MFJ-932 Mini Loop Tuner

Instruction & Technical Manual

INTRODUCTION & FEATURES

One function of the MFJ-932 Mini Loop Tuner

tunes/resonates various lengths of wire into a very Hi-Q tuned-circuit used as a transmitting loop antenna. It uses an MFJ low -loss Butterfly capacitor with no rotating contacts in this circuit. The second function is a matching network that serves to match the Hi-Q transmitting loop circuit to any length of 50-Ohm coaxial cable.

No ground, radials, or counterpoise system is required or needed. The MFJ-932

Mini Loop Tuner

tunes any shape loop: circle, square, rectangle or any odd shape. However, a wire approaching a quarter wavelength shaped as a circle is the most efficient configuration.

The MFJ-932 Mini Loop Tuner

uses fixed wire lengths, which cover about 1.5 to 1 frequency ranges (i.e. 28 – 18 or 10 – 7 MHz, etc.). Exact frequency coverage depends on each individual installation configuration involving choice of wire length and diameter, shape of loop, Mini Loop Tuner

height above ground

level, and operating environment.

MFJ-932 MINI LOOP TUNERTM FEATURES:

• Powerless: No power supply required.

• Maximum Input Power: 20 Watts (all modes)

• Small Physical Profile: 4 ½ ” W, 4 ½” D, 1 ½ “ H

• Low Radiation Angle: Rivals full size dipoles.

• Quiet Reception: Extremely quiet receiving antenna. Hi-Q rejects out-of-

band interference, reduces overloading, and rejects harmonics.

• Indoor Use: Perfect for apartments & hotel/motel rooms, antenna restricted, and portable locations.

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MFJ-932 Mini Loop Tuner

RF HAZARD BACKGROUND INFORMATION

The following WARNING should be obeyed when using the MFJ-932 MINI LOOP TUNERTM:

Instruction & Technical Manual

RF HAZARD PRECAUTIONS

WARNING

DO NOT touch or come into contact with Loop

Connectors or Loop Antenna while transmitting

YOU CAN BE SERIOUSLY INJURED !!!

Using the MFJ-932 Mini Loop Tuner voltages and HIGH CURRENTS during normal operation. The Hi-Q circuit produced by resonating the wire loop connected to the tuner, and matching it to the 50-Ohm coax supplying power creates this unique operating environment.

can, and in fact does, produce LETHAL

NOTICE

It is imperative that the operator specifically follows operating instructions and

complies with all CAUTIONS, WARNINGS, and FCC Guidelines for Human

Exposure to Radio frequency (RF) Electromagnetic Fields

Radio frequency (RF) Radiation

Radio frequency (RF) energy is one type of electromagnetic energy. Electromagnetic waves and associated phenomena can be discussed in terms of energy, radiation or fields. Electromagnetic "radiation" is defined as waves of electric and magnetic energy moving together (i.e., radiat ing) through space. The movement of electrical charges generates these waves. For example, the movement of charge in a radio station antenna (the alternating current) creates electromagnetic waves radiating away from the antenna and intercepted by receiving antennas. Electromagnetic "field" refers to the electric and magnetic environment existing at some location due to a radiating source such as an antenna.

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MFJ-932 Mini Loop Tuner

Instruction & Technical Manual

RF HAZARD PRECAUTIONS

An electromagnetic wave is characterized by its wavelength and frequency . The wavelength is the distance covered by one complete wave cycle. The frequency is the number of waves passing a point in a second. For example, a typical radio wave transmitted by a 2-meter VHF station has a wavelength of about 2 meters and a frequency of about 145 million cycles per second (145 million Hertz): one cycle/second = one Hertz, abbreviated Hz.

Electromagnetic waves travel through space at the speed of light. Wavelength and frequency are inversely related by a simple equation: (frequency ) times (wavelength) = the speed of light. Since the speed of light is a constant quantity, High Frequency (HF) electromagnetic waves have short wavelengths, and Low Frequency (LF) waves have long wavelengths. Frequency bands used for amateur radio transmissions are usually characterized by their approximate corresponding wavelengths, e.g., 12, 15, 17, 20 meters, etc.

The electromagnetic "spectrum" includes all of the various forms of electromagnetic energy ranging from extremely low frequency (ELF) energy (with very long wavelengths) to all the way up to X-rays and gamma rays, which have very high frequencies and correspondingly short wavelengths. In between these extremes lie radio waves, microwaves, infrared radiation, visible light and ultraviolet radiation, respectively. The RF part of the electromagnetic spectrum can generally be defined as that part of the spectrum where electromagnetic waves have frequencies that range from about 3 kilohertz (kHz) to 300 gigahertz (GHz). Figure 2 illustrates the electromagnetic spectrum.

Figure 2: The Electromagnetic Spectrum

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MFJ-932 Mini Loop Tuner

Instruction & Technical Manual

RF HAZARD PRECAUTIONS

FCC OET Bulletin 65, Supplement B, Evaluating Compliance with FCC

Guidelines for Human Exposure to Radio frequency Electromagnetic Fields.

The FCC Office of Engin eering Technology (OET) Bulletin 65, Supplement B,

Evaluating Compliance with FCC Guidelines for Human Exposure to Radio frequency Electromagnetic Fields impacts directly the use and operation of the

MFJ-932 Mini Loop Tuner

. It establishes safe operating distances from the loop antenna and associated power levels in order to permit the operator and persons that may be impacted by operation to exist in a safe, RF radiation hazard-free environment. Guidelines for Maximum Permissible Exposure (MPE) are defined in Supplement B of the bulletin.

IMPORTANT NOTE

Use Supplement B in connection with FCC OET Bulletin 65, Version 97-01. The information in the supplement provides additional detailed information used for evaluating compliance of amateur radio stations with FCC guidelines for exposure to radio frequency electromagnetic fields. However, Supplement B users should also consult Bulletin 65 for complete information on FCC policies, guidelines and compliance-related issues. Definitions of terms used in this supplement appear in Bulletin 65. Bulletin 65 can be viewed and downloaded from the FCC’s Office of Engineering and Technology’s World Wide Web Internet Site:

http://www.fcc.gov/oet/rfsafety

OPERATING ENVIRONMENTS

Under some circumstances, such as an antenna located unusually near humans, an indoor antenna in a living space, or a balcony-mounted antenna a foot or so away from a neighbor’s balcony, the FCC could require a station evaluation or take other action. Computer models of small HF loops, for example, yield RF fields very near the antenna that are much higher than the standard amateur radio station outdoor antenna installation yields. Therefore, when you use the MFJ-932 Mini Loop Tuner (outdoors), or one such as a hotel/motel room care must be taken not to exceed established MPE to yourself and others who may encounter the RF field associated with your operation.

in your Ham Shack, at a portable location

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