Elecraft KIO2 User Manual
Page 21
21
Connecting Other Equipment to the KIO2
The KIO2's 9-pin connector provides a number of signals in addition to those needed for the RS-232 serial
interface (Table 2). Note: Use pin 1 as the electrical ground for any external devices. Pin 5 should only be
used as the RS-232 ground return to the computer.
Table 2. KIO2 Signal Descriptions.
J1 Pin
Signal Description
Notes
1
Chassis Ground
RF/DC ground (use pin 5 for RS-232 signal ground)
2
TxD
RS-232 data from K2 to computer (RF filtered)
3
RxD
RS-232 data from computer to K2 (RF filtered)
4
ALC
Automatic Level Control from an external amp to the SSB
adapter. Refer to our web site for related application notes.
5
RS-232 Sig. Ground RS-232 ground return (for computer serial data; RF filtered)
6
AuxBus
K2 configuration network (RF filtered), intended for use
with external AuxBus-compatible peripherals. Connections
made to this line must be shielded, and total bypass
capacitance should be between .001 and .005 µF. Excessive
capacitance may cause auxBus data transmission errors.
7
RF Detect
RF level feedback (DC), intended for use with external
SWR bridges (when a KAT2 is not installed). A low-
impedance (< 100 ohms) DC signal driving this line will
override the K2's internal RF detector. Refer to the KAT2
ATU schematic for an example. Improper use of this line
could result in incorrect K2 power settings, high current, etc.
8
DC Supply Voltage
This is intended as a power-on signal from the K2, and/or
for powering low-current external peripherals. Total load
current should be kept under 50 mA continuous, 80 mA
peak to avoid damage to L1 on the AUX2 board. A 150-Ω
or larger series current limiting resistor should be used.
Bypass capacitors in external equipment must be placed on
the far end of the limiting resistor (i.e., not on the K2 end).
9
8 V Receive
8 V on receive, 0 V on transmit (approx.), current-limited to
2 mA. This signal is intended for use sequencing external
amplifiers. A new firmware feature allows the 8 V receive
line to remain low during the entire
T - R
delay to reduce
CW-mode relay switching. See the K2 Rev. 2 Firmware
manual for further details.