N8UR PPS Logging System --
Switch Configuration

The PPS logging system uses two HP 59307A "VHF Switches" to route the various PPS signals to the time interval counter. The 59307A is GPIB controlled, and each unit has two independent 4-pole, single-throw switch units.

By cascading switches, two units can provide a total of 14 inputs and outputs, in practical configurations of 10 start and 4 stop channels or 7 start and 7 stop channels. I'm currently using the 10 and 4 configuration, with the routing shown as in the table below

1A commonTo HP 5334A START 
1A1To 1B common 
1A2To 2A common 
1A3From HP 5061APPS B2
1A4From HP 5065APPS C2
1B commonTo 1A1 
1B1From CNS II 
1B2From Spectracom 8170PPS D1
1B3From Z3805A 
1B4Spare 

2A commonTo 1A2
2A1From patch 01-8
2A2From patch 01-9
2A3From patch 01-10
2A4From patch 01-11

2B commonTo HP 5334A STOP
2B1From HP 5061A
2B2From Z3805A
2B3From CNS II
2B4From patch 01-12

The cable from switch 2B to the HP 5334A STOP input is several feet longer than the cable to the START input. This provides enough delay that system noise tests can be performed by selecting the same source for both start and stop channels.