Friday, August 13, 2010

Mediumwave Oddities - Transmitter Power

We've talked about geographical mediumwave oddities for the United States, let's shift the discussion to transmitter power. Again, we will use data from current FCC records, this time from August 7, 2010. There are 4784 licensed stations in this survey. I have found 4787 licensed stations in the database, one more than the 4786 total the FCC publishes. I am excluding WR2XJR-670, Portsmouth, Virginia, a questionable FCC record for a synchronous station, and WWWS-1400 and WWGP-1050, both of which are reported licensed and on the air, but have no current antenna engineering record in the FCC database.

Daytime and nighttime data differ, so I will try to be explicit on the figures presented.


As you probably already know, 50,000 watts (50KW) is the maximum power allowed for a US mediumwave station. All 50KW stations used to be Class A clear channel stations, but that is no longer the case. 50KW stations can be Class A, Class B, or Class D, depending on the area they serve.


First of all, how many total stations are on the air during daytime hours?

All 4784 FCC-licensed stations can operate during daytime hours.

How many 50KW stations are there?

Throughout the FCC dragnet, there are 245 stations transmitting at 50,000 watts during daytime hours. 324 stations are transmitting at 20,000 watts or higher. 600 stations at 10,000 watts or higher. The vast majority, 4184 stations, transmit at a power under 10,000 watts.

Here's some figures for other power levels:

10,000 watters - 331
5,000 watters - 1172
1,000 watters - 1819
500 watters - 271

717 stations transmit with a power less than 1,000 watts during daytime hours.

Which station transmits with the lowest daytime power?

Lowly WBCP-1580, Urbana, Illinois with 135 watts. Only 10 stations total transmit with less than 200 watts.

What is the total power output of all stations combined?

A whopping 27,323,022 daytime watts! (27,323.022 kilowatts)

Currently, power companies in the US charge anywhere from about 8 cents per kilowatt hour to about 20 (Hawaii has the highest rate at 27 cents).

Considering 15 cents per kilowatt hour an average rate, how much does it cost to run all of these transmitters for one hour?

27,323.022 kilowatts per hour costs $4,098 each hour to operate. Over a 12 hour daytime period, the grand total paid to the power companies is an astounding $49,181, essentially 50 thousand dollars per half day in power costs alone.


How many total stations are on the air during nighttime hours?

4178 stations can operate during nighttime hours, out of 4784 stations total. This leaves 606 stations which are licensed for daytime only operations.

How many 50,000 watt stations are authorized to transmit at this power level at night?

97 stations are at the 50KW level during nighttime hours, versus 245 during the daytime. 122 stations are transmitting at 20,000 watts or higher (versus 324). 212 stations at 10,000 watts or higher (versus 600). 3966 stations transmit at a power under 10,000 watts.

Here are the other figures for nighttime hours:

10,000 watters - 78 (versus 331)
5,000 watters - 408 (versus 1172)
1,000 watters - 1360 (versus 1819)
500 watters - 250 (versus 271)

2031 stations transmit with a power less than 1,000 watts during nighttime hours.

Under 1,000 watts, things start to get really interesting, as nighttime operations are a totally different ballgame than daytime due to greatly enhanced signal propagation. Many, many low powered stations abound.

Which station transmits with the lowest nighttime power?

We have a tie. 14 stations transmit with a flea-power signal of only one watt! In fact, 120 stations are on the air transmitting with less than 10 watts! Between 1 and 99 watts, there is at least one station transmitting at each unit of power level, i.e., at 1,2,3,4,5,6,7,8,9,10,11,12,13....47,48,49....all the way to 99 watts.

There are 1028 stations transmitting less than 100 watts at night. Of those, 908 are at power levels between 10 and 99 watts. Between 100 and 500 watts, we have 551 stations.

So, the record holders at 1 watt output level are these 14 stations:

WNBL-1540, Booneville, IN
WRFM-990, Muncie, IN
WGAB-1180, Newburgh, IN
KBOA-1540, Kennett, MO
WZRK-1550, Lake Geneva, WI
WJJT-1540, Jellico, TN
KLKC-1540, Parsons, KS
WSRY-1550, Elkton, MD
WSQR-1180, Sycamore, IL
KDYN-1540,Ozark, AR
KLEY-1130,Wellington, KS
WCKB-780, Dunn, NC
WPGR-1510, Monroeville, PA
WHFB-1060, Benton Harbor, MI

Of these, Indiana is the clear winner with 3 of the lowest powered stations in the US.

What is the total power output of all nighttime stations combined?

10,856,121 nighttime watts (10,856.121 kilowatts). This is opposed to the daytime total wattage output of 27,323,022 watts. The nighttime power level is about 40% of the daytime level. One hour of nighttime electricity costs the radio stations $1,628. Twelve hours of operation at night costs $19,541.

So, the total cost of mediumwave broadcast transmitter power in the US, operating 24 hours per day, comes to approximately $68,722, based on a 15 cents per kilowatt hour charge by the power companies!

How many of you mediumwave DXers have heard these flea power stations, under 10 watts? Maybe we should have a certificate award for receiving a prescribed number of flea powered stations, perhaps under 100 watts, or even under 10 watts?

Coming up next: Mediumwave Oddities - Towers

More power to you, mediumwave DXer!


Unknown said...

When you mention 1 watt
station power, do you
mean radiated power of 1 watt or transmitter power of, say 1 watt.
ERP of 1 watt would indicate a greater transmitter power to achieve this figure, under normal circumstances
Best regards
Finbar O'Connor EI0CF


Hi Finbar,

All powers indicated are transmitter power and not ERP.

Radio-Timetraveller (Bill)

Unknown said...

Hello Bill,

Thanks for confirming the power is actual transmitter output.
Amazing to find stations
power levels so low.
Nice web site and most
Finbar EI0CF

Stephen said...
This comment has been removed by the author.
Stephen said...

I noticed something seemed to be missing.... What stations actually are authorized with a HIGHER power at night than they are allowed in the daytime? I'll mention one - 760 KFMB San Diego, CA, about 7 miles from me. In the daytime they're only allowed a paltry 5kW omnidirectional, but at night they step up to 50kW (estimated RSSI on my PL-380, if it didn't cap at 63dBu, would be around 82dBu or so), with a 3-tower directional array that has a null toward Detroit to protect WJR. The bulk of the power is sent in a swath from north to west to south (actually rotated a bit counter-clockwise from that), with north and south I think getting slightly more power than west, if I remember correctly.

What others do you know of, especially those authorized with 50kW at night and less in the daytime?


Hi Stephen,

An interesting point, and one I had not thought of.

I tweaked my database code and came up with the following results:

73 stations run higher power at night than during the day.

KFMB-760 is the only one which runs 50KW at night. The next closest in higher nighttime power is WLIB-1190 at 10KW/30KW, in New York, NY.

The one with the most power differential is WLAN-1390, 18KW/1100KW, Lancaster, PA, at 61.1 times more power at night.

I'll write this up soon and add it to the blog.


Radio-Timetraveller (Bill)