11
FT-8800R Operating Manual
I
NSTALLATION
Note that 9600 bps packet transmit-deviation adjustment is very critical to successful opera-
tion, and can only be accomplished using a calibrated deviation meter (such as that found on
an FM Service Monitor used in a communications service center). In most cases, the Packet
Data Input level (set via a potentiometer inside the TNC) must be adjusted to provide a
deviation of ±2.75 kHz (±0.25 kHz). Check with your packet node’s sysop if you have any
questions about the appropriate deviation level for your network. Note also that high through-
put on 9600 bps frequently requires strong signals, so you may wish to consider the use of a
directional antenna such as a Yagi for communication with high-speed packet nodes.
The setting of the 1200 bps Packet Data Input level is much less critical than it is at 9600 bps,
and satisfactory adjustment to the optimum (±2.5 ~ ±3.5 kHz) deviation can usually be done
“by ear” by adjusting the TNC’s 1200 bps TX Audio Level potentiometer so that the outgoing
packets (as monitored on a separate VHF or UHF receiver) are approximately the same level
as (A) the DTMF tones or (B) the 1750 Hz Burst tone produced using the microphone.
Finally, note that the Menu (“Set”) mode allows you to set the Packet data rate (1200 or
9600 bps) independently for each band, and set the Packet Receiving Band (Main band,
Right band, or Left band: Transmit band is fixed on Main band). If you have trouble getting
your
FT-8800R
to respond correctly during packet operation, check to be certain that you
do not have Menu #26 (
PKT.SPD
) set to the wrong data rate, and/or Menu #27 (
PKT.RXB
)
set to the wrong operating band.
B
ASE
S
TATION
I
NSTALLATION
13.8VDC
ANT
EXT SP
DATA
DATA
OUT
DATA
IN
PTT
PKS
GND
DATA IN
DATA OUT
(9600bps)
13.8VDC
ANT
EXT SP
DATA
DATA
OUT
DATA
IN
PTT
PKS
GND
DATA IN
DATA OUT
(1200bps)
9600bps Packet Setup
1200bps Packet Setup
