Saturday, August 28, 2010

Early Radio Publications

This week I uncovered a treasure trove of early radio magazines in downloadable PDF format. If you love radio history like I do, you will enjoy browsing through these publications. Two magazines are represented.

Radio Broadcast Magazine, available issues from 1922 through 1930, covers in great detail the early years of broadcasting and includes much technical information for the early experimenter. The advertisements from these years alone are worth checking out. Articles in Radio Broadcast run the entire spectrum from MacMillan's expedition to the Arctic in the summer of 1926 to detailed descriptions of current vacuum tube circuit technology, projects for the amateur, to coverage and questions about governmental standards and practices in this early era of radio, to programming content and personalities. What a wealth of interesting information for the historian!

Radio Broadcast Magazine

Also available on this site is Radio Corporation of America's Radio Age  Magazine, available issues from 1942 through 1957. This was a quarterly publication produced by RCA. A lot of interesting World War II coverage can be found during the war years, as well as new technology.

Radio Age Magazine

Be sure to check these out while they are still available.

Tuesday, August 24, 2010

Internet Radios

I guess I'm too much of an old timer to get into this current Internet "radio" thing. Too many years spent toying with tuned circuits and antennas, too many years a radio DXer, radio listener, even a radio "Ham" - some 47 years - though I really haven't done the Ham thing for some time. WE7W lives on though, and I still keep my license current.

For better or for worse, sometimes words or things in life "evolve" over time to mean different things. I'm thinking radio is becoming one of them. Radio at one time meant "wireless" transmission of electromagnetic waves through the air, from starting point to finishing point. It was picked up magically with a wire or a coiled loop, fed to a tuned circuit which selected one signal out of many, detected and converted to audio which was then amplified so you could hear it. Internet "radio" is no such thing. No aerial, no tuned circuits, no detection. A friend of mine says real radio has to pass through your body (meaning: the waves) - that's the definition of real radio. I say that too, plus a tuned circuit must surely be involved, and almost certainly a detector. Internet "radio" has none of the above. What would Marconi think?

Internet radio probably is radio only in the sense that for a small segment of its "transmission" to you, millions of digital bits are perhaps beamed up to a satellite and back down. Maybe. The rest of its journey, both before and after, it is transmitted through wire or fiber optic cable, passed from one computer device to another to another, arriving in numerical perfection just as it was sent, down to the last, solitary, Boolean bit.

Merriam-Webster says about the noun RADIO:
a: the wireless transmission and reception of electric impulses or signals by means of electromagnetic wave.

b: the use of these waves for the wireless transmission of electric impulses into which sound is converted.
As I was saying: "waves", like the kind that pass through your body.

There was even a time when I used to subscribe to various radio magazines, until the articles became more computer articles than radio articles, each filled mostly with links to web sites. Recent shortwave magazine articles I've seen basically contain narrative on how to navigate a radio station's web site to get its streamed Internet content. Radio magazines have evolved to something different than they once were, too.

I just don't get it. There is no magic for me in Internet radio. See accompanying photo of toaster, er, I mean Internet radio. How about you?

Maybe it's the semantics of the whole thing that bothers me more than anything else. The new "radio" is not the old radio, and never will be. It is something wholly different.

Okay, a reality check. Yes, I do listen to a podcast now and then (now there's a new word unleashed on modern society for you: podcast), or streamed audio via my desktop or laptop. I've even been known to listen to a streamed radio station on occasion (try streamed KTNN-660 sometime, The Navajo Nation, 50KW out of Window Rock, AZ for an interesting experience). But the listening is done for "content", without the accompanied magic of original radio. There is no "feel" to it. I attempted to capture this feel in another post in this blog. I was talking about mediumwave towers:

...."A tower is a thing of beauty to the radio aficionado....Ah, the mediumwave broadcast tower! Think of it! Stately, striped sentinels with strobe lights flashing, they number thousands and thousands across the country, each emitting invisible waves of electrons through the late night air, spanning that mysterious thing called "the ether" to deliver communication to unknown distant masses. It conjures up thoughts of far-away points on the landscape, souls crouched in cramped corners with headsets fixed in the dark of night, straining to make sense of distant babble through static crashes and heterodynes. That would be me. The whistle of a far off freight train gives the same feeling of wonder."

Internet radio does not. Do you like your toast light or dark?

Sunday, August 22, 2010

Mediumwave Oddities - Towers

Today, we move on to tower oddities in the mediumwave broadcast band. Broadcast towers have always been an interesting subject to me. Did you see the news earlier this month on the WWVA-1170 towers collapse, due to severe storms in the Wheeling, WV area? The photo at left shows how they looked in the 1940s. WWVA-1170 started broadcasting in 1926.

Like last time, we will use data from current FCC records dated August 7, 2010. There are 4784 licensed stations in this survey. Previous posts in this series were Mediumwave Oddities - Transmitter Power and Mediumwave Oddities - Geography. Information has been gathered using the Radio Data MW program.

Again, daytime and nighttime data will differ. I will be explicit on which is which when the statistics are presented.


Many mediumwave broadcast stations use multiple tower arrays to direct their signals towards intended markets, or away from other stations which they may cause inteference to. There are thousands of towers out there.

If we total all the towers of all the mediumwave stations transmitting in the daytime, how many would there be?

Answer: 7164. That's a lot of metal in the air.

Out of the 4784 licensed stations, how many stations have only one broadcast tower?

3569 stations have only one broadcast tower, which is 75% of all broadcast facilities. Surprisingly, the remaining 25% actually have more towers total than the single-towered 75%. Multi-towered stations average 2.95 towers per facility.

Essentially, a station with one broadcast tower has an omni-directional signal pattern, in other words, the station broadcasts with equal signal strength in all compass directions. Multiple tower arrays use phasing techniques to form skewed patterns of radiation, often in figure-eight or cardioid shapes. The lobes, or strong points of the pattern are directed towards market areas of interest. The nulls, or weak points of the pattern, are positioned toward areas to lessen interference with other stations or unwanted markets.

Back to tower counts, how many stations have two broadcast towers?

515, or 10.7 percent of the total have two towers.

How about three towers?

384, or 8 percent of the whole. The percentage drops dramatically off from there of course.

Which station has the most broadcast towers in use during daytime hours?

That would be KNTH-1070, Houston, Texas, with 11 towers. They are arranged in an odd grouping of three parallel rows of 3 each, with towers #10 and #11 jammed between the two rows. The rows head generally in a south to north direction. KNTH-1070 uses two less towers (9) during nighttime hours.

Are there more towers in daytime use east of St. Louis, Missouri, or west of St. Louis?

East of St. Louis, there are 4240 towers in use during daytime hours. 2924 towers are used west of St. Louis.

Radio station signal patterns are sometimes further modified at the tower site by what are called "augmentations". Augmentations are modifications to the standard broadcast signal pattern, usually to further null the signal strength in a certain direction to bring it into FCC "signal contour" compliance. An interesting discussion can be found on augmentation over at The Virtual Engineer AM forum.

Stations can have up to 28 augmentations to their signal pattern. This must be a technical nightmare for the broadcast engineer.

Which station has the most augmentations?

Four stations have 28 augmentations in use during daytime hours.


Again, like we saw in Mediumwave Oddities - Transmitter Power, nighttime seems to be the more interesting as it has more odd variety.

How many total towers are used for broadcasting during nighttime hours?

Answer: 7877 towers. 713 more towers are used at night than during the day.

Being a mediumwave DXer, you know that signals travel much farther at night than during the day, commonly upwards of 1,000 miles and more. Stations often must follow different signal pattern guidelines at night to prevent interference to distant stations. This generally requires use of either a different tower arrangement or different number of towers, or both. Stations also may operate at reduced power at night.

Which station has the most broadcast towers in use during nighttime hours?

That would be KFXR-1190, Dallas, Texas, with 12 towers. They are arranged in two parallel rows of 6 each, heading from southeast to northwest. KFXR uses only 4 towers during daytime hours. Texas holds the record for stations with the most broadcast towers for both nighttime and daytime hours. They always do things in a big way in Texas.

Are there more towers in nighttime use east of St. Louis, Missouri, or west of St. Louis?

East of St. Louis, there are 4427 towers in use during nighttime hours. 3450 towers are used west of St. Louis.

Which station has the most augmentations?

Nine stations have 28 augmentations. Among them again is KFXR-1190, Dallas, Texas. I think KFXR-1190 should be considered for the record here. It is the station with the most towers (12) and tied with 8 others with the most augmentations.

I was thinking about ground radials this morning, which are the (generally) buried wires that are placed under broadcast towers to create the artificial ground that they operate over. Usually broadcast towers must have at least 90 quarter-wave length wires, and as many as 120 or more. Seeing as how we know the number of broadcast towers used in nighttime operation, the following question occurred to me:

If we assume 120 radials under each tower, how many total ground radials are in use?

Answer: 945,240. Almost a million radials.

Using an average length of 245 feet for each radial (a quarter wave length at 1000 KHz), how may feet of radials lie under mediumwave broadcast towers in the US?

231,583,800 feet. That is 43,860 miles of wire, enough to encircle the world almost two times. Time to buy stock in copper.

Hope you have enjoyed this series. For more mediumwave oddities on RADIO-TIMETRAVELLER, see the Tower Talk article.

The WWVA-1170 towers after the August 4th, 2010 storm.

Wednesday, August 18, 2010

Australian Mediumwave Database

I came upon an official Australian government link (ACMA - The Australian Communications and Media Authority ) the other day which documents licensed mediumwave stations for Australia in PDF format. Digging deeper, I found an official government database, published in XCEL (.XLS) format. This file has the basic information, such as call sign, frequency, latitude, longitude, power, and service. No tower information is available, and only a crude maximum signal strength of the antenna pattern's maximum lobe is given. It is also a comprehensive file of all Australian transmitter data: MW, FM, and TV. None the less, it will be useful.

Using an XCEL viewer, the mediumwave information can be copied in its entirety and saved as a text file. Further "massaging" can put it into a proper format. Then the information can be incorporated into a database of Australian mediumwave stations. The file is updated once per month.

List of licensed broadcasting transmitters (main page)

Broadcast transmitter data (EXCEL format)

Mediumwave stations, by call sign order (PDF)
Mediumwave stations, by frequency order (PDF)
Mediumwave stations, by area served (PDF)

Tuesday, August 17, 2010

Radio Station Databases 101

Let's explore the details of some of the governmental mediumwave station databases available to us. Much information is there for the taking if you can extract it. But where do we find it? And how do we do that?


Although the FCC's AM Query provides a usable output of AM radio station information, the entire story is not told. Much technical information is left out, particularly field strength, tower, and other engineering data, information which can be found by digging deeper into the actual FCC database files. AM Query is simply a mechanism that extracts predetermined data from the real database, hidden in numerous files in the cellars of the FCC web site. These files are found in the FCC's Consolidated Database System (CDBS) electronic filing system. This database contains some very interesting and useful data.

CDBS file index via http site
CDBS file index via ftp site

If you choose the FTP route, be aware that some modern browsers are deprecating FTP mode.

I wanted more information than the FCC's AM Query could deliver. CDBS files document in detail the AM, FM, and TV (including digital) services, right down to measured signal strengths and distance between towers. Being an old programming hand for many years, some time ago the idea occurred to me to write a program which would use these files as input and provide a varied display of interesting and useful station data. My Radio Data MW program was born, and has become a sort of sideline hobby for me ever since. If I ever get it to a distributable state, I may one day publish it.

For the enthusiast or budding programmer wanting to extract information out of these files, where does he or she begin? Actually, once unzipped, all of these files are simple text files which can be opened in any text editor. My choice for a text editor in recent years has been Notepad++. It is an excellent freeware editor, useful not only for text files but also programming and scripting.

Okay, now that we have our text editor/viewer, how and where does one begin to gather information on mediumwave stations? From the CDBS database, here are the FCC files which must necessarily be examined. The pertinent information in each file is described. Be careful to note that these FCC files cover all services: AM, FM, and TV, including Traveler's Information Services.

The facility file, (facility.dat)
This is the key file for unlocking all the others. There is one record here for each facility (station). The facility ID number within each record will eventually lead you to the rest. Keep it handy.

Information found in this file:

* The station's facility ID
* The station's service community city, state, and country
* The station's call sign
* The station's frequency
* The station's current licensing status
* The station's digital status (IBOC or not)

The engineering index file, (am_eng_data.dat)
Multiple records usually exist for each facility. The application ID in each record points you to the station's antenna system record in am_ant_sys.dat. Keep this handy too.

Information found in this file:

* Cross reference back to facility ID
* The station's class (A, B, C, D, or unknown)
* The FCC application ID (an identifying number)

The application file, (application.dat)
This file contains a historical list of all applications filed by every station in the FCC database. It is a huge file, some 60MB.

Information found in this file:

* Cross reference back to facility ID
* The FCC application ID with cross reference to the more commonly known application resource number (BL-19990713DC)
* A secondary call sign reference (can be an old or new call sign)
* A secondary frequency reference (can be an old or new frequency)

The antenna system file, (am_ant_sys.dat)
Multiple records usually exist for each facility. An individual record exists for each service a station is authorized to use (Unlimited, Daytime, Nighttime, Critical Hours), and multiples of these may even exist. In this file we get to the heart of the station's information.

Information found in this file:

* Cross reference back to application ID
* The station's antenna system ID
* Number of augmentations to the signal pattern
* Hours of operation (its service: Unlimited, Daytime, Nighttime, Critical Hours)
* The station's latitude (tower site coordinates)
* The station's longitude (tower site coordinates)
* The station's power for this service
* RMS signal strengths at 1 kilometer in three varieties
* The station's domestic licensing status
* Number of towers
* Antenna mode (DA2, ND1, etc.)
* Indicator showing if record is current or archived (important)

With a station's latitude and longitude, using proper programming it is possible to calculate its distance and bearing from your home location. It is also possible to calculate the sunrise and sunset times at the distant transmitter. Using the station power and/or measured signal strengths at 1 kilometer, and knowing the distance you are from the transmitter, the path loss and a rough relative received signal strength can be calculated for daytime reception of stations within a few hundred miles of your home location. Of course nighttime, with its enhanced signal propagation and atmospheric conditions, would preclude any calculated value.

The towers file, (am_towers.dat)
In short, this file contains everything you need to calculate a station antenna's broadcast pattern. You can also plot tower positioning. A record exists for each tower in a station's tower array.

Information found in this file:

* Cross reference back to antenna system ID
* Antenna system resource number (ASRN - FAA number)
* Tower height, measured in various ways
* Top load switch (tower type: 0, 1, 2, 3, etc.)
* Signal field strengths
* Relative tower positioning
* Tower spacing
* Tower phasing

AM broadcast station signal pattern graphs are calculated through a rather complicated formula. A description of this and other formulas can be found at:

Directional Antenna Systems
Modification of directional antenna data

An excellent treatise on using these formulas can be found at:

A Modern Method Of Predicting AM Tower Vertical Radiation

The augmentations file, (am_augs.dat)
This file documents the augmentations to the station's signal pattern. Multiple records can exist for each facility if augmentations are used. Radio station signal patterns are sometimes further modified at the tower site by what are called "augmentations". Augmentations are modifications to the standard broadcast signal pattern, usually to further null the signal strength in a certain direction to bring it into FCC "signal contour" compliance.

Information found in this file:

* Cross reference back to antenna system ID
* Azimuth of augmentation
* Span (in degrees) of augmentation
* Radiation strength of augmentation

Using this information, we can further refine a generated graph of the station's signal pattern.

The facility index, (fac_party.dat)
This file is a simple cross reference of facility ID to owner information in the party.dat file.

Information found in this file:

* Cross reference back to facility ID
* Index forward to party ID (for owner information)

The owner information file, (party.dat)
A huge file of all kinds of owner information.

Information found in this file:

* Owner names and addresses indexed by party ID

And finally, to decode what all the above files mean, be sure to examine:

Code Table
Engineering Data Description (PDF)


Counting Licensed Stations

Have you ever seen the official FCC licensed station count? Lately the count has been 4786. The FCC uses the facility.dat file to determine this number. In this file, each facility has one line of information. There is a field in each line indicating the station's licensing status. Simply by totaling the number of LICEN (licensed) and LICSL (licensed but silent) entries gives you the licensed count. Total the LICSL entries by themselves, and you have a count of the number of licensed but silent stations.

Counting Digital (IBOC) Stations

Again, the the facility.dat file is used. A single character field in each record contains the letter "H" or "D" if a station is digital. Currently no "D", or purely digital mediumwave stations exist, they are all hybrid ("H") IBOC. Non-digital stations show a blank field. Count the number of "H"s, and you have the IBOC count.

Gathering It All

Combine the facility.dat file information with the engineering data index file information (am_eng_data.dat) and you know the station's class and most recent application ID. Look for this application ID in the antenna system file (am_ant_sys.dat) and you will have the station's position coordinates, hours of operation, and a host of other information. Cross reference the facility ID to the party.dat file and find the owner information. And finally, inspect the am_towers.dat file using the station's antenna system ID for the detailed field strength and tower information. Use the tower information and theoretical field strengths to calculate the antenna broadcast pattern.

Simple, it is not. It is overwhelming at first. The FCC's file layout is not friendly. But a tremendous wealth of information is available to the enthusiast or programmer who wants to work at it.


The FCC database has information on Mexican stations. Use it with caution. The two neighbor countries on our borders, Mexico and Canada, must file with the FCC for every station that wishes to broadcast. We do the same for them. Much of the data within is hopelessly outdated, especially the data for Canada, as Canada continually loses many of its mediumwave stations to the FM service.

The published link for official Mexican government mediumwave data is:


It is a PDF document of all supposed currently licensed and on the air mediumwave stations. All I have ever been able to get out of this link is a "503 - Service Temporarily Unavailable" response.

The next best bet comes from the official Mexican telecommunications site, Cofetel. The only government list I have found available, also in PDF form, is the Infraestructura de Estaciones de Radio AM list. Though the URL address is dated 2008, the actual PDF retrieved is dated 31-Dic-2009, or December 31, 2009, so hopefully the information is somewhat current.

Unfortunately, this station information lacks transmitter latitude and longitude coordinates, and a host of other needed technical information. It might be possible to correlate the Mexican stations with the FCC's database to get this. I haven't put forth the effort yet.


Canada has a search page of its own for broadcasting databases, but like the FCC's AM Query, the entire story is not told and much technical information is left out. But we are in luck. It turns out that Canada has a set of files that will fill the bill for all technical information.

The Industry Canada engineering database houses it, with link shown just below.

Industry Canada engineering database (

Rather than simple text files, Canada has chosen a dBase file format (.DBF) for its files. Download and unzip and you will have them. Though the records are somewhat textual in nature, they are more like XCEL records and a text editor cannot be used to view them. You must use a specialized viewer in order to look inside.

CDBF for Windows by WhiteTown Software, which used to be available as a shareware DBF viewer/editor/converter, seems now to be purchase only. A demo is available but usable only for a short time. A better choice now is Exportizer, totally free. It also supports conversion of the DBF file to other formats.

Once again we have our text editor/viewer, how and where does one gather information on Canadian mediumwave stations? From the Industry Canada database files, here are the ones which should be examined.

Information found in this file:

General AM station data, like the FCC's facility.dat file.

Information found in this file:

Tower info, like the FCC's am_ant_sys.dat and am_towers.dat files.

Information found in this file:

Description of codes used.

Information found in this file:

Country codes

Information found in this file:

Owner information

Information found in this file:

Signal pattern augmentations, like the FCC's am_augs.dat file.


Combining the Industry Canada information with the FCC's, we now have two countries with a wealth of information about their mediumwave service. If the missing information from Mexico's PDF file can be extracted from the FCC's database (namely the latitude and longitude coordinates of the stations), we can then create a single, comprehensive file with all the station data we need.

See also: Canadian/Mexican AM Station Search

Another country of interest but outside the North American realm is Australia. Under a separate post, Australian Mediumwave Database, I show where to find detailed technical information on Australian mediumwave stations.

The current build of Radio Data MW.

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!