WATCH DOG TIMERS
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Watch Dog Timers
Jumpers are appropriately labeled on the PC board. Refer to the parts location diagram for help in
locating them. Also refer the Assembly and Disassembly section for information on obtaining ac-
cess to the interior of the TNC.
KAM – VHF Timer – Jumper K3
This jumper is provided to disable to disable the VHF watch dog timer. The timer is disabled if the
jumper is installed. Time-out of the KAM will occur after approximately 2.5 minutes, un-keying the
VHF PTT line. The KAM is shipped with the jumper not connecting the jumper posts; therefore, the
timer is in effect.
KAM – HF Timer – Jumper K4
This jumper is provided to disable to disable the HF watch dog timer. The timer is disabled if the
jumper is installed. Time-out of the KAM will occur after approximately 2.5 minutes, un-keying the
HF PTT line. The KAM is shipped with the jumper installed; therefore, the timer is not in effect.
KAM Operating Note
As shipped from the factory, the VHF watch dog timer is in effect and the HF watch dog timer is
not. The HF timer is not enabled since it cannot distinguish between RTTY and Packet signals.
Should you plan to operate a mode other than Packet, the HF timer will limit your transmission to
approximately 2.5 minutes if it is enabled.
KPC-4 – Timers – Jumpers K5 (Port 1) and K6 (Port 2)
These jumpers are provided to disable the watch dog timers. The timer is disabled if the jumper is
installed. Time-out of the KPC-4 will occur after approximately 2.5 minutes, un-keying the PTT line.
The KPC-4 is shipped with the jumpers not connecting the jumper posts; therefore, the timers are
in effect. Should you wish to have a SHORTER timer interval, it may be obtained by changing the
appropriate resistor shown in the following chart:
KPC-2400
The KPC-2400 is shipped with the Optional Watch Dog circuit board installed. (This applies to units
after serial number 73400. An optional circuit board may be ordered from Kantronics for units with
serial numbers before 73400 and should be installed for digipeater or unattended operation.)
K1 jumper on both pins disables watch dog circuit. If harness is unplugged from watch dog board
a 2.2 kΩ 5 % ¼ Watt resistor MUST be inserted between pins 1 and 5 wiring harness connector to
allow normal operation. WARNING: A resistor larger than ¼ Watt will damage the connector. PTT
shut-off time is approximately 2 minutes.
KPC-1 and KPC-2
These TNCs do not come with a watch dog timer installed. An optional circuit board may be or-
dered from Kantronics and should be installed for digipeater or unattended operation.
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