Well, a trap is just that. It passes frequencies below the resonant
length of the trap, but stops signals at the resonant frequency. I
am surprised that a tuner can't tune the very high swr two half wave
elements, but automatic tuners don't have the range I have become
accustomed to. You will need a grid dip meeter to make sure the
traps are resonant. Maybe their is a more modern way to do that to.