Operating instructions

MFJ-933 Loop Tuner
TM
Instruction & Technical Manual
- 18 -
SYSTEM OPERATION
Step 4
Make the following preliminary settings on the controls of the Loop Tuner:
• TUNING control to position “0, Low Freq”.
• MATCHING control to position “10, Min C”.
Step 5
Tune the transceiver or receiver to the band and frequency of interest and “Ear-
ball” tune the MFJ-933 Loop Tuner controls for maximum noise and S-Meter
reading. “Ear-balling”, like “Ball-parking” is a term often used to describe the
listening process as used to hear a “peak” in reception before actually applying a
transmit signal to the tuner. The tuner will produce a peak when the proper
positions for the controls are achieved. The normal process consists of the
following suggested instructions:
• Slowly rotate TUNING control clockwise while listening for a peak until you
reach position “5, High Freq.”
• If no peak is found, re-position TUNING control to “0, Low Freq.”
• Rotate MATCHING control counter-clockwise one position to “9”.
• Slowly rotate TUNING control clockwise while listening for a peak until you
reach position “5, High Freq.”
• If no peak is found, re-position TUNING control to “0, Low Freq.”
• Rotate MATCHING control counter-clockwise one more position to “8”.
• Slowly rotate TUNING control clockwise while listening for a peak until you
reach position “5, High Freq.”
• Repeat this sequence until the MATCHING control reaches position “0”.
• If no peak is found, the loop length is incorrect for the frequency of
interest. (See Table 3 for the Most Efficient Loop Length for the frequency
of interest.)
• Once a peak is found, alternately adjust TUNING and MATCHING
controls until the peak is maximized.
Step 6
Apply 10 to 20 Watts of power to the MFJ – 933 Loop Tuner 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.