LP-FM vs 'Full Service' FM Question

[MHVRadiofan]

LP-FM stations are non-commercial broadcasters licensed to operate with 100 watts or less. Why are some stations such as the new WWQZ 89.5 Baptist Village, MA at 33 watts listed as a ‘full service’ station.

 

[Kmagrill]

They are a class A. Class A is anything from 100W up to 6kW. In the case of WWQZ, they are transmitting from 117m using only 33W, but the combination of height and power exceeds the coverage of an LPFM. Or, to put it another way, an LPFM at 117m would only be licensed for a few Watts.

 

[w9wi]

http://edocket.access.gpo.gov/cfr_2009/octqtr/47cfr73.211.htm

Class A stations may have an ERP less than 100 watts
provided that the reference distance, determined in accordance with
paragraph (b)(1)(i) of this section, equals or exceeds 6 kilometers.

Translation:
- A new "full-service" FM station must be of at least Class A.
- A Class A station must either:
- Use 100 watts ERP, or
- Deliver at least 1mV/m (60dBu) of signal at a distance of 6km.

According to the propagation curves, 100 watts at 35m delivers 1mV/m at 6km. So a station with an antenna height of more than 35m can be licensed at an ERP of less than 100 watts. WWQZ's antenna is 117m high. (at that height, it could be licensed with an ERP as low as 8 watts)

 

[PTBoardOp94]

WWQZ probably could not have been an LPFM because the rules for licensing an LPFM are stricter than a class A (at least in the NCE reserved portion of the band). That will be changing, assuming the FCC ever implements the Local Community Radio Act of 2010.

It also could not have been licensed as an LPFM because there has not been an LPFM filing window in 7 or 8 years, and the application for WWQZ did not take place until 2008.

 

[DudeFan]

Also, non-grandfathered non-reserved band Class A's must meet the class-minimum 6kw ERP (any combination of height/power).

Reserved-band Class A's can be, as you noted, licensed with much less.

Like the example you noted, the difference between a Class A and LPFM becomes how much protection they enjoy from interference.

The FCC will implement the Local Radio Act. It's just a matter of whether it is this century or next.

 

[w9wi]

Also, non-grandfathered non-reserved band Class A's must meet the class-minimum 6kw ERP (any combination of height/power).

Reserved-band Class A's can be, as you noted, licensed with much less.

The rule I posted is applicable to non-reserved band stations. (I quoted it out of the commercial FM rules; the same rule is incorporated by reference for reserved-band stations)

What is different for commercial stations... is that they can only be built on allocated channels. A channel can only be allocated if a site exists where a 6kw/100m station could be built without causing interference. However, once the channel is allocated, a station can be authorized on that channel at any power between the 100-watt minimum and the 6kw maximum.

There are no allocated channels in the reserved band. You can use any frequency that doesn't cause interference.

In practice it's pretty rare for a commercial Class A to apply for anything less than the maximum permissible power. However, it is legal and does occasionally happen. I know I've seen two in Texas since the beginning of the year.

 

[Kmagrill]

There was also one in Florida's panhandle operating at low power to save electricity and quite a few more all over that are licensed under 73.215 directional rules.

 

[TomT]

Many Class A stations are stuck at the equivalent of 3 kw/100 meters because they are short-spaced to other stations. Although stations can reach agreement to mutually raise power (for example, two 98.3 stations near me), if an agreement can't be reached they are stuck.

Also you can operate at reduced power to use a site that may be slightly short-spaced. One of my stations operated under that basis, although we eventually ended up with full power after a later move by the adjacent channel station.