[Elecraft] Remote Antenna Switches and K2 Questions

[Brian Hunt]

Looking a the schematic it appears they use 0V, +V, -V and ACV for the 4 switching states but only + or - voltage is applied to the relays. The big cap is used to smooth out the AC ripple.  I would put a back diode across each relay coil and add a MOV of appropriate voltage across C203 (V to ground).  Reference the QST article in January 2013 issue. I built one with those guidelines and it's been fine for a couple of years. 

73,
Brian, K0DTJ