MFJ-998 Legal Limit IntelliTuner Automatic Antenna Tuner Instruction Manual
© 2007-2010 MFJ Enterprises, Inc.
23
Function
Indicates By
One Beep
Indicates By
Two Beeps
By Pressing
Antenna 1 2 [ANT] < 1 second
Memory Bank
Bank A
(1 beep)
Bank B
(2 beeps)
Bank C
(3 beeps)
Bank D
(4 beeps)
Off
(5 beeps)
[ANT] > 1 second
Bypass Toggle
Bypass Mode
(L = 0 and C = 0)
Restore Last L/C Setting [TUNE] < 0.5 second
[C-DN] + [L-DN]
Tuned SWR
SWR
≤ 1.5
(1 beep)
SWR
≤ 2.0
(2 beeps)
SWR
≤ 2.5
(3 beeps)
SWR
≤ 3.0
(4 beeps)
SWR
> 3.0
(“SWR”)
[TUNE] for
0.5 to 2 seconds
StickyTune
TM
On Off [TUNE] for 2 to 10 seconds
[TUNE] < 0.5 sec. To Bypass To Tune [TUNE] > 10 seconds
Manual L/C
Adjustment
L/C at Lower Limit
L/C at Upper Limit
[C-DN] or [L-DN]
[C-UP] or [L-UP]
Capacitors
Switch to
Antenna Side
Switch to
Transmitter Side
[C-UP] + [C-DN]
Tuning Mode Automatic Semi-Automatic [TUNE] + [ANT]
Memory Overwrite X [TUNE] + [C-DN] + [L-DN]
Amplifier Bypass
Control
TM
On Off [MODE] + [L-UP] + [L-DN]
Disable Radio
Interface
X
[TUNE] + [MODE]
+ [POWER]
Delete
Confirmation?
DELETE BANK
DELETE ANTENNA
TOTAL RESET
Yes
DELETED
or
RESET
No
CANCEL
[C-DN] for YES
or
[L-DN] for NO
Table 2. Tuner Beeps.
Transceiver Foldback
Modern transceivers with solid-state finals usually have a foldback circuit to protect the final transistors
from damage due to high SWR. A foldback circuit detects the SWR during transmit and reduces the
output power as the SWR rises above a preset threshold, usually 2:1. The higher the SWR the lower the
power is set to prevent damage.
If your transceiver has a foldback circuit, you can simply key down and tune at any power level from 5 to
100 watts. If your transceiver does not have a foldback circuit, you should manually set the power level
to 10-30 watts for tuning. At higher power levels, the reflected power that occurrs during tuning can
damage your transceiver or amplifier and causes component arcing which can damage the relays in the
tuner.
Check your transceiver owner's manual to see if it has a foldback circuit. When an amplifier is used, the
amplifier must be bypassed during tuning.
Note: MFJ recommends that a transceiver-specific interface cable be used between the MFJ-998
and your transceiver, and that an amplifier enable/bypass connection be used between the
MFJ-998 and your amplifier, to ensure that tuning only occurs at low power.
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