Hi Kevin, when you plug just the center of your coax connector in to your
antenna port, you are using the coax and antenna as a long wire, wich is
why it will hear more than if you have it fully connected. The dual band
antenna is not enough of an antenna to hear anything at the lower
frequencies! Hope that helps!
73:
J.
John Jacques
Amateur Radio Station: KG7FA
"Where Cat Is, Is Civilization!"