microHAM STATION MASTER Manual page 26

The EXT position connects the common terminal to the special "input" pin on the PORT A connector. This pin is
used for a POSITIVE external control voltage up to 28V DC.
The INT position connects the common terminal to the SRC/SNK jumper. In the SRC position, the common
terminal is connected to Station Master's power supply (+13 Volts); in this configuration the outputs are voltage
sourcing. In the SNK position, the common terminal is connected to Station Master's ground; these outputs are
sinking (switch to ground).
PORT B: Contains six (6) outputs with single common terminal (B1-B6) and four (4) outputs (B7B10) with
isolated contacts. The common terminal of relays B1-B6 can be configured for internal or external power and
source/sink operation by using the PORT B jumpers in the same manner as the PORT A jumpers.
NOTE: Default factory settings for both PORT A and PORT B are INT / SRC (internal sourcing).
microHAM © 2016 All rights reserved
Simplified schematic of PORT A
Simplified schematic of PORT B
26