Bob,I haven`t used one of these in years ,But, I think that 4 volts at
rec terminals would be acceptable ..At 4 volts on rec terminals not
enough current would flow to do any damage to the input circuit..High
voltage to rec terminals ,like lightning surges etc are the ones that
do damage.. GL Harold W4PQW

Harold, Thanks for your reply. It puts things in perspective. 73, Bob AD3K