Question:  Please contact us ASAP. We have two tempest 2400 4 channel wireless systems and are having real difficulty syncing both stations. Yes we have the sync cable in place but the beltpacks can't communicate across the two connected base stations.  Please advise what we are doing incorrectly?
Answer:  The accu-sync cable only provides the RF hopping pattern sync stability between the two Tempest base stations.  No audio path linking is done through this ribbon cable. 
To provide the audio link between the two base stations the user has to link the 2-wire PL channels between bases together for each channel (in this case if all 4 channels are used each channel has to be linked together, that is A to A on both bases, B to B, C to C and D to D etc) and then each channel has to be connected back to a Clear-Com main station or power supply.  Verify that the base station front panel slide switches are set to Clear-Com and that each channel is set to 2-wire mode (3-pin XLR input / output).  Also auto-null each base station to reduce any PL echo in the system. 
If the base stations are used in stand alone mode (no wired PL connection) setup one base station in "Master Mode"  this allows the master base station to supply +24Vdc to the other connected base station's PL connectors so that the PL audio interface can work properly on all connected base stations. 
Up to 10 base stations can be connected in this manner. 
Do not mix 2400 base stations with 900 base stations when using Accu-Sync, they are not compatible in this mode.