FT-2600M O
PERATING
M
ANUAL
14
Note that 9600 bps packet transmit-deviation adjustment is very critical to successful op-
eration, 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.
The setting of the 1200 bps Packet Data Input level is much less critical, 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 by the MH-36
B6J
or MH-42
B6J
microphone.
Typical connections to a TNC are shown below.
Installation
Finally, note that M
ENU
#18 (“PCKT”) allows you to enable or disable the microphone
during packet operation. Normally, the default setting (“Microphone Disabled during Packet
TX”) is appropriate; when the microprocessor detects PTT input from the Data connector,
the microphone will be disabled.
