The Radio Information Board

I am trying to place a variable pot between these 2 radios to be able to set 3 KHz dev. A 22K in a previous posting only gives me 2.2 Khz out, a 10k variable pot maxes at 2.6 Khz. Any suggestions. Also, need to use an external 2 tone encoder with the VHF radio, should the tone input be connected to ...

Waht brand of duplexors should you use with this repeater. Will the RFS PD 633 6 cavity work ?

Thanks.