AM – Page 21 – Engineering Radio

AM Radio Improvement Plan

There has been lots of hand wringing and ink spilled regarding the sorry state of affairs in the senior service. AM is plagued with problems; interference, poor bandwidth, etc. To that end, the NAB has launched studies and initiatives and hired all sorts of pricey consultants to consult with. Here is my own AM improvement plan and it is rather simple:

Clean up the transmitter site.
Get rid of AM HD radio.
Variable IF bandwidth receivers.
Improve Programming.

How many of us have seen AM transmitter site dumps? Deferred maintenance, malfunctioning directional arrays, trees growing up on the ground system, flooded buildings and ATU’s, rusty towers, transmitters not a full power, ground system deteriorated or missing all together, just to list a few problems. Many AM transmitter sites are technical disasters. Think that these things have no bearing on the AM station’s signal? Think again.

differed maintenance, AM transmitter site — Differed maintenance, AM transmitter site (there is a tower in there somewhere)

Trees growing around the tower base can attenuate the signal by 30%. A comment from a well known engineering firm:

…Recently XXX field engineers had occasion to measure an AM station at XXXX kHz before and after removing vegetation in the vicinity. The station had a quarter-wave tower. The base area had grown up in brush and hardwood trees to a height of perhaps 30 feet (9m) and this extended from near the base across the entire ground system. After clearing (cutting, no ground system disturbance), the signal measured at some 16 locations on four radials went up a uniform amount of about 15% or 1.2 DB. That’s about a 30% increase in radiated power…

That is an inexpensive power boost and they didn’t even have to file with the FCC! A 1 – 2 dB power gain is pretty nice and can mean the difference between a listenable signal and static. How many times have I heard the lament that AM band is full of noise and not listenable. Certainly, there are major challenges in the urban listening environment. Putting forth a better signal will overcome some of this electrical noise.

There is a reason why engineering standards were developed for the physical plant; they work.

There is no cure for the noise that AM HD Radio puts out into the adjacent channels. This self interference benefits none, not even the station transmitting AM HD Radio. This dubious technology has proved itself a non-starter and should be discontinued. For smaller station owners, the cost of implementing AM HD Radio is prohibitive. Licensing of a proprietary modulation scheme, new transmitting equipment, specialized exciters plus any needed bandwidth improvements to AM antenna arrays can easily exceed $100,000.00. Unfortunately, it is often the small AM radio operators that are making a good showing, and serving their community of license and making money. These are the very stations that are hurt the most by adjacent channel AM HD Radio interference.

Receiver design over the last twenty to thirty years has been the greater issue with perceived low AM broadcast quality. AM receivers have an average bandwidth of just 3-4 KHz, which is slightly better than telephone quality. AM broadcasting has gotten a bad wrap because of this and there are many comments about how AM is “inferior quality” to FM. With a quality older receiver, AM can sound very good. Of course, the receiver manufactures all point adjacent channel interference as their rational for reducing IF bandwidth. Why not leave it in the hands of the user? The GE Superradio had this feature with a “wide” and “narrow” setting for AM reception. They worked remarkably well. A receiver could also be designed to automatically increase IF bandwidth at higher received signal strengths.

Finally, as the saying goes; Garbage in, Garbage out (GIGO). This holds true for many things including radio programming. Expecting that mediocre satellite syndicated news talk will garner great ratings and huge revenues is silly. For years and years, station owners have put minimal effort into AM radio and expected big returns. It is not working. AM stations that go against that trend; those with unique formats (Gasp! Music, on AM?), local content, and community oriented programming can and do succeed. They are fighting an up hill battle in both directions. With all of the business pressures from larger broadcast groups, interference issues and negative viewpoint on the viability of the AM band, one wonders how long they can last.

Hums no more

My first job as Chief Engineer was at WPTR and WFLY in 1991. I was young and it was a learning experience. The WPTR transmitter was a Harris MW50A, which reliably went off the air every six months. The transmission lines going out to the towers had fallen off of their wooden support posts, trees were growing up in the antenna field, and sample lines were going bad. In short, it was a mess. Even so, the station was well-known and well-liked in the community. One could still see echoes of greatness that once was.

When Crawford Broadcasting purchased the station in 1996, they put much money and effort into renovating the facility. Replacing the Harris transmitter with a solid state Nautel, replacing the phasor and transmission lines, cutting the trees from the field, painting the towers, renovating the old transmitter building into a new studio facility, and finally removing the old Butler building that formerly housed the “Gold Studios.”

Then the depression of 2008-20?? hit. Once again, the place has fallen on hard times. WDCD-AM has been silent since last April. The cost of running the 50 KW AM transmitter being too much to bear in the current economy. Formatically, the station drifted around for several years. According to the STA to go silent:

WDCD WILL SUSPEND OPERATIONS FOR A PERIOD DURING WHICH IT WILL DEVELOP AND PREPARE TO DEPLOY A NEW PROGRAM FORMAT AND REPOSITION ITS VOICE AND IDENTITY IN THE COMMUNITY.

They may need to do something slightly non-religious to survive.

While we were waiting for the utility company to turn the electricity back on after yesterday’s fire, I took a short walk around the WDCD-AM site and took some pictures. The transmitter disconnect thrown, fuses are pulled, it is kind of sad to see the Nautel XL-60 dark:

Nautel XL-60 AM transmitter. WDCD Albany, NY

I apologize greatly for the blurry picture, it was taken with my cellphone camera, my good camera being back at home on my desk. Radio stations, when they are on the air, seem like they are alive. Machinery hums, fans move air, meters move, and there is a sense of purpose. Silent radio stations give me a sense of foreboding like something is terribly wrong.

View of the towers without Butler Building. The towers are 340 feet tall, which is 206 electrical degrees on 1540 KHz. The site was constructed like this to suppress skywave signals toward ZNS, Nassau, Bahamas. ZNS is the only clear channel station allotted to the Bahamas by NARBA. The other station WDCD is protecting is KXEL, Waterloo, IA. During the 90’s, I received many QSL requests from Norway/Finland and even a few from South Africa. I know that the station had a large following in most of New England.

WDCD tower base, tower three — WDCD tower base, tower one (furthest from building)

Tower one tower base. This IDECO tower had to have the top 60 feet replaced after it was hit by an airplane in 1953. The tower base also had to be replaced in the late 1980’s as it was crumbling and falling apart. To do this, Northeast Towers used railroad jacks and jacked the entire tower up off of the base insulator. They re-formed and poured a new base, carefully letting the tower back down on a new base insulator about a week later.

WDCD towers looking back toward the transmitter building

Antenna field looking back at the transmitter building. If you work at radio transmitter sites, I encourage you to take pictures of all these things, as someday, they will all be gone.

The “bomb shelter” and 220 KW backup generator, constructed by FEMA in 1968 as part of the BSEPP. This used to have an emergency studio and enough diesel fuel for fourteen days of operation. Now, the bomb shelter has a kitchen and bathrooms. The underground storage tank no longer meets EPA standards and has been pumped out.

The Onan generator is conservatively rated at 220 KW, surge rating 275 KW. These things were way over-constructed, so it is likely it would easily run 225 KW all day. It has an inline six-cylinder engine with a massive flywheel. When the engine is stopped, it takes about twenty seconds for the generator to stop turning.

National Grid, 3 pot, 480 volt, 3 phase service, original to the 1947 building.

I wonder if it will return.

Troubles at the Tower

Troubles at the AM tower; I don’t know why, it won’t switch power.
Over the phone I can tell, the program director’s day is not going very well.
Press the “day” button but there is no kerchunk, the directional coupler shows the load is junk.
Out into the big field, I go to find the problem quickly and fix it just so.
The wind is cold, the snow is deep, I think of the contract terms I must keep.
Reaching the tuning house, take out the keys, lock, do not be frozen, please.
Once inside, there I find, no big surprise, the mice have been a working this pre-sunrise.
A nest they have build in a most inconvenient place, in the back of the phasor wiring chase.
Oh, the wires they have chewed, the circuit’s destroyed, all for the lack of mousetraps deployed.
As I reach in to clean out the mess, the smell of mouse makes me gag, I confess.
The fuses are blown, the contactor is jammed, perhaps, if I am lucky, I can move it by hand.
A large screwdriver strategically employed, I pry up slowly, further damage to avoid.
The bar thunks up, the contacts engage, the transmitter is ready to apply amperage.
Call on the cell phone, tell them it’s fixed, stand back and watch the base current meter, transfixed.
Then; Up it goes! Wonderful radio frequency current flows!
I clean up, lock the door, lock the gate, carrying bad news the owner will hate.
The damage is grave, the repair bill is steep, if a good relationship with the FCC you desire to keep.
Business is off, the accounts are low, is this really necessary, he wants to know.
The terms of the license are your obligation to keep, getting caught out of tolerance will not be cheap.
Looking forlorn, the owner says in disgust, it is only the AM, but fix it if you must.
Happy as a lark, with a song in my heart, I dig though the manual and order the part.
Time to go home, eat breakfast, brush teeth, take a shower. I have another client to see before the noon hour.

Dedicated to all those who have been there, done that and the breed of RF men and broadcast engineers who are slowly fading away.

WNAW North Adams

Originally signed on as WMNB in 1947, it is a Class C AM station on 1230 KHz, one of thousands in the country. Initially, it had a power of 250 watts, upgrading at various times to its current power of 1,000 watts.

WNAW-WUPE-FM, North Adams, Ma circa 2012

What is different about this station is the studio building. It is located in its original place on Curran Highway on the south side of North Adams. The studio is a late Art Deco design, complete with a small glass atrium in the lobby. Like many older radio stations, this installation was built on a raised floor. The walls and doors are all well constructed for maximum sound attenuation. The doors are large, heavy, and solid wood.

WNAW news room, formerly the performance studio — WNAW newsroom, formerly the performance studio

Inside, the original studios are laid out with a control room, a broadcast studio and a live performance room. At one time, the live performance room had a grand piano. Several times per week, live music shows were broadcast on the station. There was a large newsroom, and a big corner office for the General Manager and sales managers.

WNAW studio, looking into the control room. Back in the day, the announcer, whose only concern was announcing, worked in a separate studio from the engineer on duty, who worked console in the control room. The audio level limiting consisted of turning down the level on the console if the announcer started speaking loudly. They often communicated with each other with hand signs through the windows.

At the time that WMNB was signed on, the Adams/North Adams Massachusetts area was in the heart of the northeast manufacturing belt. Sprauge had a capacitor plant in Adams, GE was making plastics in Pittsfield, There were many textile mills still in operation and so on. The population was predominantly working middle class.

Obviously, the console has been changed since those days. The current console is a Audio Arts R-60. This serves as the control room for WNAW and WUPE-FM. The programming for WUPE-FM comes from Pittsfield on a T-1 line. From here, it is relayed to the transmitter site on a 950 MHz STL. WNAW transmitter is located about 2/10 of a mile south of the studio building on Curran Highway. It consists of a skirted self supporting tower with a Gates 1 solid state transmitter.

Equipment racks containing the T-1 equipment, modulation monitors and STLs. Note the very old Moseley TRC-15 remote controls. We have been unwiring these at the transmitter sites and disconnecting the TELCO lines. The transmitter sites now have Sine Systems dial up remote controls.

In 1961, WMNB-FM (now WUPE-FM) signed on the air from a tower north east of downtown, off of Mohawk Trail (MA route 2). It broadcast on 100.1 MHz with an ERP of 1,000 watts using a Gates FM1B transmitter.

WNAW continues on today as a community based radio station and is well liked and supported.