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Summary of Contents for MFJ MFJ-933C
- Page 1 High-Efficiency Magnetic Loop Tuner MFJ-933C INSTRUCTION MANUAL ©2020 300 Industrial Park Rd. Starkville, MS 39759 P: (662) 323-5869 F: (662) 323-6551...
- Page 2 The copy of this manual provided to the customer will not be updated to reflect current data. Customers using this manual should report errors or omissions, recommendations for improvements, or other comments to MFJ Enterprises, 300 Industrial Park Road, Starkville, MS 39759. Phone: (662) 323-5869 Fax: (662) 323-6551 Business hours: M-F 8:00 AM - 4:30 PM CST.
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Page 3: Table Of Contents
The MFJ-933C ........ -
Page 4: Radio Frequency Hazards
MFJ-933C High-Efficiency Magnetic Loop Tuner Instruction & Technical Manual RADIO FREQUENCY HAZARDS BACKGROUND INFORMATION The following warning is printed on the back of the MFJ-933C High-Efficiency Magnetic Loop Tuner ™. WARNING DO NOT touch or come into contact with Loop Connectors... -
Page 5: An Electromagnetic Plane Wave
MFJ-933C High-Efficiency Magnetic Loop Tuner Instruction & Technical Manual Figure 1: An Electromagnetic Plane Wave have short wavelengths, and Low-Frequency (LF) waves have long wavelengths. The frequency bands used for amateur radio transmissions are usually characterized by their approximate corresponding wavelengths, such as 12, 15, 17, 20 meters, et cetera. -
Page 6: Rf Precautions
HF loops, for example, yield RF fields very near the antenna that are much higher than the standard amateur radio station outdoor antenna installation fields. Therefore, when you use the MFJ-933C High-Efficiency Magnetic Loop Tuner ™ in your shack, at a portable location, or in a hotel room, care must be taken to exceed established MPE to yourself and others who may encounter the RF field associated with your operation. -
Page 7: Rf Radiation Exposure Concerns
OPERATING ENVIRONMENTS & GUIDELINES Tables 1 and 2 list various MFJ-933C High-Efficiency Magnetic Loop Tuner ™ operating environments, average power level, and safe distances that should provide compliance with the FCC’s MPE recommendations and standards for controlled and uncontrolled populations. -
Page 8: 100W Indoor And Outdoor Operating Environment
MFJ-933C High-Efficiency Magnetic Loop Tuner Instruction & Technical Manual Table 1: 100W Indoor and Outdoor Operating Environment Frequency (MHz) Controlled Population Uncontrolled Population Height (m) Exposure (ft m) Exposure (ft m) 1.18 0.36 1.68 0.51 1.25 0.38 2.48 0.75 1.88 0.57... -
Page 9: The Mfj-933C
• MFJ-933C High-Efficiency Magnetic Loop Tuner ™ • Wire or Coax Loop (not included) The MFJ-933C Deluxe High-Efficiency Magnetic Loop Tuner ™ has two functions. First, it uses various lengths of wire to create a very-high-Q tuned circuit that is used as a transmitting loop antenna. -
Page 10: Features
MFJ-933C High-Efficiency Magnetic Loop Tuner Instruction & Technical Manual The MFJ-933C High-Efficiency Magnetic Loop Tuner ™ has a mount for either an MFJ-57B or MFJ-58B PVC Cross assembly or your own homebrewed assembly. The assembly is inserted into the three-quarter-inch PVC receptacle mounted on the top of the unit’s cover. Assembly takes less than five minues from opening the packaged kit to operating! Care should be taken, to secure the... -
Page 11: Loop Theory
4. COAX OUTPUT: This is one of two output ports for using a coax loop instead of wire. The MFJ-933C High-Efficiency Magnetic Loop Tuner ™ front panel controls and indicators function to permit matching the wire or coax loop to the coaxial line at the input of the tuner. Refer to Figure 4 and the numbered component locations. -
Page 12: System Setup
flowing in the soil via capacitance between the loop and soil surface. These are all reduced by increasing the height of the MFJ-933C above the ground as measured from the tuner box. An operational height equal to... -
Page 13: Loop Construction
Designing an outdoor loop for a band such as 7 MHz could be a challenge yet result in a very good radiator and especially good receiving antenna for DX-ing and rag-chewing. We at MFJ think the experimental aspects of the MFJ-933C are exciting, and can provide hours of quality operating, even at QRP levels. -
Page 14: System Operation
The MFJ-57B or MFJ-58B make this simple by providing a precut PVC frame and wire lengths. Step 3 Set up the MFJ-933C High-Efficiency Magnetic Loop Tuner ™ as illustrated in Figure 6. -12-... - Page 15 • Once a peak is found, alternately adjust the TUNING and MATCHING controls until the peak is maximized. Step 6 Apply 10 to 20 Watts of power to the MFJ–933C and adjust the TUNING and MATCHING controls for minimum SWR on your external SWR/Wattmeter. Readjust the controls until you see no further improvement in minimum SWR.
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Page 16: Quick-Start Instructions
S-Meter reading. The tuner will produce a peak when the exact position for the controls and switches is found. Step 5 Apply 10 to 20 Watts of power to the MFJ–933C and adjust the TUNING and MATCHING controls for minimum SWR on your external SWR/Wattmeter. Readjust the controls until you see no further improvement in minimum SWR. -
Page 17: Mfj-933C Accessories
This concludes the MFJ–933C High-Efficiency Magnetic Loop Tuner ™ operating instructions. MFJ-933C ACCESSORIES Two kits are available for use with the MFJ-933C High-Efficiency Magnetic Loop Tuner ™ , and each gives the operator expanded operational capabilities and use of pre-made/fabricated wires and equipment. These kits are: •... - Page 18 USER NOTES...
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