FWIW - When I purchased a used (excuse me - pre-owned) RCB-5 antenna
switch, I had to replace a few of the LEDs. Upon opening the control box, I
noticed that there was a RS bridge rectifier pack soldered to the board in
place of what I assumed was the normal single diode. I figured this was
installed by the previous owner to boost the DC available to the relay
contacts at the end of a LONG control cable. (I bought the switch from a
TT'ian and I've seen his station/antenna field.)
It might be easy enough to replace a single half-wave rectifier with a
full-wave bridge and increase the pull-in voltage available to the relays,
thereby causing them to wipe more vigorously upon closure.
Gene Smar AD3F
P.S. After I replaced the LEDs in the control box, I bypassed the control
cable screw terminals (which are in parallel with the LEDs) with 0.001 pF
caps. I still have the LEDs in service after four months and more than a
few lightning/thunder storms.