Southern California's 50,000 Watt AM Stations

[semoochie]

You mention 1090 in Seattle. Their nighttime directional pattern is intended to protect Mexico. If and when XEPRS operates at night with full directional power giving them an ERP of around 200 kW or so, this station actually causes interference to Seattle's 1090 within 20 miles of the station's transmitter. Except for frequent selective fading distortion XEPRS's signal strength is "local" from BC to BC...

1090 didn't used to come into Tacoma for beans but the situation seemed to have improved many years back.

 

[davideduardo]

I know a number of directional AM stations no longer want to maintain complicated tower arrays. And they want to collect the money that selling those large transmitter sites would bring. (How much did Cumulus pocket by selling WMAL/WSBN 630's acres of transmitter land north of DC? It was tens of millions of dollars!)

Two different situations:

In big metro areas, stations that were built in the 30's out in the boonies are now sitting on land worth more than the station. So, many sell the land and move to a new site or a shared site. In some cases, like KABC, there was no degradation of the signal. In others, like several of the DC stations, the new site is not as good.... but no AM in DC ever had a good signal after the post-WW II sprawl of the District and suburbs.

The other case involves complicated directional stations in smaller markets like Tallahassee or Macon. The markets are mostly FM listening... much more than the larger markets... and a translator covers the market pretty well. Cut the engineering costs, save on land property tax, utilities and go to low night power but non-directional. The translator will do better than the AM ever did.

So these stations consolidate on one tower and go non-directional 24/7, even if it means a big loss of nighttime coverage.

In many cases, the translator does better than the directional signal. In lots of cases, the nulls of the directional are over the newer big population areas of the market, in fact.

Often they have an FM translator for nighttime listening. Or they sacrifice their nighttime listeners for the cash, especially if they're running a format like talk, religion or adult standards that doesn't have a lot of nighttime listening anyway.

So many of those AMs had very limited protected signals at night, while a translator at a good height covers better and with a clean signal and audio.

But that's not XEPRS. An all-sports station would have significant nighttime listening for live sporting events (even though The Mighty 1090 is not the Padres flagship anymore).

We don't know if that facility will really be implemented. The 800 night watts won't even get to downtown, and be useless for SD coverage.

Could it go 50,000 watts non-directional in the daytime if it wanted? A check of stations on 1090 AM shows almost nobody on that frequency nearby in Mexico or the U.S.

There are stations on 1070 (LA) and 1080 and 1100 and 1110 that need protection to some extent.

There's a fulltime 50,000 watt station on 1090 in Seattle but that's far enough away that in the daylight they wouldn't overlap. There's also a Denver station running 50,000 watts by day, with a big reduction at night. So that's not a problem either. Nothing else within 1000 miles.

You have to protect adjacent channels and next adjacents, too.