Cecil, W5DXP wrote:
"I`m putting a vertical back up for transmitting and will probably
receive on my horizontal dipole."

If your grounded tower is near 1/4-wavelength on your favorite band, why
not shunt-feed the tower and use it as your radiator?

On the other hand, if you want to support another antenna and eliminate
radiation from the supporting tower, outrig a wire from the tower top,
hanging parallel to the tower, and connected to the tower top through an
L-C network tuned to make current in the outrigged wire equal ond
opposite that in the tower. The balanced currents cancel the tower`s
radiation. This may be tedious for frequency hopping, but it works.

Best regards, Richard Harrison, KB5WZI