XiD-P cable box RF Output Channel 3/4 change

I recently "upgraded" to X1 capable boxes for all my TVs and the RF (coax) output seems to be always on Channel 3.  My previous (non-X1) boxes allowed me to set the RF output to Channel 4 and the picture was always clear.  I must be able to use Channel 4 as there is a local over-the-air broadcast station (KYW-Philadelphia) in my area that broadcasts on Channel 3.  I live only a few miles from their towers and there is too much interference on my TVs when using the RF output of my XiD-P cable box when is is set to Channel 3.  

Can someone tell me how to change the XiD-P box's RF output from Channel 3 to Channel 4?

PS. don't suggest using the HDMI output as I have external equipment that requires RF