pa0rdt-mini-whip-schemaCircuit of the PA0RDT Mini-Whip. The "probe" is a piece of copper, about 3 x 4.5 cm. The circuit is powered with 12 Vdc over coax. Circuit of the PA0RDT Mini-Whip. The “probe” is a piece of copper, about 3 x 4.5 cm. The circuit is powered with 12 Vdc over coax.