MFJ-926B HF Automatic Remote Antenna Tuner
Instruction Manual
2010 MFJ Enterprises, Inc.
4
Internal Components
The MFJ-926B was designed for remote operation with no manual operation required. The tuning process
starts automatically when the transmitter is keyed with at least two watts of power when the SWR is
greater than 2:1. The MFJ-926B has been pre-set with default settings at the MFJ Factory. However, if
you remove the unit from the box, you can change the default settings as well as verify proper operation
of the unit. The following will guide you through the process.
•
SWR LED:
A green LED that illuminates when the SWR is 1.5 or less.
•
TUNE LED:
A red LED that illuminates when automatic tuning is in progress.
•
TUNE Button:
Has three different functions based on the length of time you press and hold it before
releasing. Press and release [TUNE] quickly (less than 0.5 second) to bypass the tuner. One flash
indicates bypass mode, where RF from the transmitter goes directly to the antenna with no matching.
A second quick press toggles the tuner back to its last L/C setting, and the tuner responds with two
flashes.
Press and hold [TUNE] for 0.5 to 2 seconds to start the automatic tuning process. Tuning starts after
the [TUNE] button is released during the 0.5-2 second time frame. The transmitter must be keyed
first with at least two watts of power. When the SWR is already below the target SWR of 1.5,
pressing [TUNE] will fine-tune the match for a lower SWR, if possible. When the automatic tuning
is completed, a series of flashes indicates the tuned SWR where one flash indicates an SWR of 1.5 or
less, two flashes indicate an SWR of 1.6 to 2.0, three flashes indicate an SWR of 2.1 to 2.5, and four
flashes indicate an SWR of 2.6 to 3.0. For SWR above 3.0, “SWR” (di-di-dit di-dah-dah di-dah-dit)
will be sent on CW and indicated on the green LED.
“
StickyTune
” enables the tuning process automatically when the transmitter is keyed with at least two
watts regardless of the SWR. To toggle the
StickyTune
mode on and off, press and hold the [TUNE]
button for two seconds. One Flash indicates “on” and two Flashes indicate “off”. The default is
“off”..
Automatic/Semi-Automatic Tuning Mode
The Automatic tuning mode should always be left on (default is “on”. In automatic mode, the tuning
routine is automatically started when at least two watts of power is applied and the SWR is greater
than 2.0. In semi-automatic mode, the tuning routine starts only when the [TUNE] button is pressed
for 0.5 to 2 seconds. Since the [TUNE] button is only available when the unit is opened up, the Semi-
Automatic mode should NOT be selected. Simulataneously pressing [TUNE] and [ANT] toggles
between automatic and semi-automatic tuning modes. One Flash indicates automatic mode and two
Flashes indicate semi-automatic mode.
Note:
During the tuning process, the tuner will make some noise. These are the relays
switching at a very high rate and is normal. Do not be alarmed.