Expandable multiport transfer switch

A transfer switch having a test signal input and first and second ports. The transfer switch includes a first routing switch and first and second port termination switches. The first routing switch has a routing switch input for receiving the test signal input and first and second outputs. Each output is connected to the routing switch input by a first switching element and each output is connected to ground by a second switching element. The first and second port termination switches are connected to the first and second outputs, respectively, of the first routing switch. Each termination switch includes a common-base transistor, and preferably, a Darlington amplifier with feedback. The common-base transistor is connected to the output of the routing switch and the Darlington amplifier has an output connected to a corresponding one of the first and second ports. The first and second switching elements are controlled such that only one of the first and second outputs is connected to the routing switch input at any given time. A transfer switch having 4 output ports can be constructed by including second and third routing switches and third and fourth port termination switches of the types described above. A transfer switch having 2 output ports can be constructed by the successive addition of routing switches and port termination switches.