MFJ-998RT Legal Limit IntelliTuner
TM
Automatic Remote Antenna Tuner Instruction Manual
© 2011 MFJ Enterprises, Inc
MFJ-998RT Version 1A
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matching. One beep indicates changing to bypass mode. Also, the decimal point in the SWR reading is
replaced with a comma.
Pressing [TUNE], [C-DN] and [L-DN] simultaneously overwrites the tuner memory with the current tuner
setting; settings with SWR greater than 3.0 will not be stored. One beep indicates memory overwrite.
Morse Code and Beeps
If not enough power is applied for tuning (less than five watts), the display will flash INCREASE POWER
three times and “QRO” (dah-dah-di-dah di-dah-dit dah-dah-dah) will be sent on CW. Increasing the input
power above five watts ends this message. When input power is too high, the tuner enters a self-
protection mode. The tuner will not allow any of its relays to change. This feature is to prevent damage to
your tuner.
If too much power is applied when tuning, the tuner will cease the tuning routine, flash DECREASE
POWER three times and send “QRP” (dah-dah-di-dah di-dah-dit di-dah-dah-dit) on CW. This occurs when
the forward power exceeds 75 watts and the SWR is greater than 3.0, or when the forward power
exceeds 125 watts regardless of the SWR. If more than 1500 watts is applied to the tuner, the tuner will
go into bypass mode, flash OVERLOAD three times and send “QRT” (dah-dah-di-dah di-dah-dit dah) on
CW. If the tuning process is activated under these conditions, the tuner will not start the tuning. It will
display a warning message on the LCD and send the appropriate code on CW. The following table shows
the various tuner beeps:
Function
Indicates By One Beep
Indicates By Two Beeps
By Pressing
Antenna Bank
1
2
[ANT] <1 second
Memory Bank
A
1 Beep
B
2 Beeps
C
3 Beeps
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 seconds or
[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 0.5-2 seconds
StickyTune
TM
ON
OFF
[TUNE] for 2-10 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
Figure 9 Beep Indicators
Transceiver Foldback Circuit
Modern transceivers with solid-state finals usually have a foldback circuit to protect the final transistors
from high SWR, which can damage or destroy them. 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 must manually set the power level to 20 watts or less for tuning. At higher power
levels, the reflected power occurred during tuning can damage your transceiver and causes component
