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MFJ-1278B MULTI-MODE ADVANCED OPERATION
signals up to 9600 baud, but an external modem is required for operation above 1200 baud.
An optional 2400 bps PSK modem board is available from MFJ Enterprises, Inc. This 2400
bps PSK modem board can be installed inside the MFJ-1278B. Radio data rate of 2400/9600
is selectable with software command by the MFJ-1278B. When an external modem is
installed and when it is in selected to operate the TURBO LED on the front panel of the
MFJ-1278B will light. Contact MFJ Enterprises, Inc. for more detail. For installation of an
external modem, see APPENDIX F in this manual for more details.
Special Protocol Timing
You can set up a connection time-out with the command CHECK, which specifies a time in
multiples of 10-second intervals. This function prevents the MFJ-1278B from getting stuck in
a connection when the other station disappears for longer than the specified time. The MFJ-
1278B uses this time somewhat differently depending on the setting of AX25L2V2.
The command RESPTIME sets a delay between the receipt of a packet and the transmission
of the acknowledgment packet. This delay is used to prevent collisions between an
acknowledgment and another packet from the sending station. This is primarily necessary
during file transfers; otherwise the delay is best set to 0. During file transfers the stations
receiving the file should set RESPTIME to 10 or 12 (default).
The timing of packet transmission in Transparent Mode is determined by the command
PACTIME. You can choose the way packet transmission is timed. If you are typing input to
a remote computer it is usually best to have packets transmitted at regular intervals. If your
computer is operating a remote-host or bulletin board program you should send packets after
an interval with no further input from the computer. You can enable the use of PACTIME in
Converse Mode with the command CPACTIME.
Monitor Functions
The MFJ-1278B's protocol is designed for setting up "circuits" between two stations.
However it can also operate in a mode more suitable for a "net" or "round-table" discussion
with several participants, although reliable reception of all transmissions by every station
cannot be guaranteed. This is done by enabling the monitor functions. Most of the monitor
functions are described in Chapter 4.
Monitoring is enabled by the command MONITOR ON, and separate monitor functions are
individually enabled.
If connected packet QSOs are taking place on the frequency of your group conversation, you
may wish to ignore all connected packets while your group operates in unconnected mode.
The command MALL OFF causes the MFJ-1278B to ignore connected packets.
If you want to be able to monitor packet activity when your station is not connected, but have