MFJ-991B IntelliTuner Automatic Antenna Tuner
Instruction Manual
2005-2012 MFJ Enterprises, Inc.
22
Power-Down Circuit Test
When the 12 VDC power to the tuner is turned off, the tuner saves all settings to non-volatile memory.
The Power-Down Circuit Test checks the power down detection circuitry. It is recommended that this
test be done immediately after the regular self-test described above.
Note:
The tuner must be reset to factory defaults before performing this test.
Here is the test procedure:
1.
Make sure power to the tuner is off.
2.
If the tuner has been reset to factory defaults, skip to step 6; otherwise continue with step 3.
3.
Press and hold
both
the [TUNE] and [L-DN] buttons while turning the power on.
4.
Release both buttons when both meter needles read full scale.
5.
Turn the power off.
6.
Press and hold
only
the [L-DN] button while turning the power on.
7.
If the power down detection circuitry is okay, both meter needles will go to full scale. If there is a
problem, the forward needle will bounce and the reflected needle will read 40, per Table 3 above.
8.
Turn the power off.
Relay Test
WARNING:
Turn off the transmitter power or disconnect the transmitter before performing
this test; otherwise, damage to the tuner can result.
To test the relays and their control circuitry, press and hold the [C-DN] button while turning the power
on. Both meter needles will bounce. Release the button. The relays are tested in groups of four as shown
in the table below. The [C-UP], [L-UP], [C-DN] and [L-DN] buttons are used to toggle each relay in
each group of four. Press button to engage the relay and release it to disengage the relay. Listen for relay
clicks. Press the [TUNE] button to proceed to the next group of four relays. There are 18 relays in the
tuner. Repeat the above procedure to test all the relays. Normal operation is resumed after this test. The
reflected power needle indicates which group of relays is being checked as follows:
Reflected Needle
[C-UP]
[L-UP]
[C-DN]
[L-DN]
1-watt mark
1
Not used
3
4
2-watt
mark
5 6 7 8
3-watt mark
9
10
11
12
4-watt
mark
13 14 15 16
5-watt
mark
17 18 19
Keys Radio
Interface
Since there are no relays #2 and #20, pressing the [L-UP] button in the first group and the last button [L-
DN] in the last group will not produce a click.
