• Get involved.
    We want your input!
    Apply for Membership and join the conversations about everything related to broadcasting.

    After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
    If you use a disposable or false email address, your registration will be rejected.

    After your membership is approved, please take a minute to tell us a little bit about yourself.
    https://www.radiodiscussions.com/forums/introduce-yourself.1088/

    Thanks in advance and have fun!
    RadioDiscussions Administrators

Third and fourth adjacent rules for up coming educational band translator window

R

Radio Bob

When I read the FCC rules prohibiting overlap of a proposed translator with an existing full power station on a third or fourth adjacent channel I wonder if there is an exception to the rule because where I live there are many translators operating in violation of the rules relative to third and fourth adjacent channels. In one case we have a full power on 104.7 and a translator on 105.1 located on the same tower! Anybody know what's up with that? Thanks Bob
 
Let’s see if I can explain this assuming that the translator wasn’t licensed under the rules prior to 6/1/91 and the full-power station is not a Class B or Class B1 (which have slightly different rules). To be licensed, on a second adjacent or third adjacent channel (400 kHz. or 600 kHz. away) the translator’s 100 dBu contour can’t overlap the full-power station’s 60 dBu contour (a 40 dB difference). In practice - due to the power levels involved, the type of the translator’s antenna, and the height of the translator’s antenna - the translator’s 100 dBu contour can be engineered to be “in the air” and not reach the ground or any building where a receiver might be. The FCC allows a waiver of the overlap that occurs above ground or building level. As long as the co-channel and first adjacent channel interference requirements are also met, the translator can be licensed. Second adjacent translators are common around antenna farm areas where the full-power station is close by and the translator’s interfering contour can be kept from reaching the ground or buildings.
 
I am reasonably certain that waiver has been applied to many of the Albuquerque translators up on Sandia Crest. It's so high up, the prohibited interference never extends to ground level.
 


Back
Top Bottom