By Ed Stroh

(Reprinted from the September 1997 of DX Chicago)

I recently had the opportunity visit a local radio station. The station is WEJM AM. Although these were the call letters of the station at the time that I visited it, I believe that the call letters of this station have since changed, because the station was in the process of changing ownership around the same time that I was there. This was only the transmitter site that I visited, not the studios. This site is located in Burnham, Illinois, about 4 blocks east of Torrence Avenue at about 142^nd Street. My visit was not by invitation, nor was it planned. I guess you could say it was sort of by accident that I was able to take the "Grand Tour". You see I work for ComEd, and I was at the transmitter site doing electrical work, when the station electrician/engineer showed up. I did not get his name, but he was very friendly and was eager to show me around and answer any questions that I had.

This is a rather very unique AM station. This site in Burnham, Illinois is only used at night. The daytime transmitter is somewhere in Chicago according to my "tour guide". Another unique thing about WEJM is the fact that they use more power at night, than they do during daytime. Most AM stations are just the opposite; they decrease their power at night. WEJM uses 1,000 Watts during the day and 5,000 Watts at night. Their signal is directional at night, with the strongest signal current lobe favoring northeast, toward Lake Michigan. The engineer said that is strange, because their target audience is Chicago, which is toward the north to northwest.

The antenna system consists of 6 towers, which I believe are 244 feet tall. He was telling me so much information in a short period of time that I am not positive on the tower height, but I think he said 244 feet. The coaxial cables leading from each of the towers back to the transmitter building are all exactly the same length. The reason for this is so that the signal arrives at each tower at exactly the same time. Taking into account that radio signals travel at the speed of light, which is 186,000 miles per second, the time difference of the signal arriving at each tower, if the cables were different lengths is so small, that I would think that it would be almost immeasurable. Apparently it does make a difference though. The transmitter building, which is nothing more than a concrete block building about 25 feet long by 15 feet wide, is in the middle of the property with 3 towers on either side of the building. The distance from the farthest north tower to the farthest south tower is about the length of 2 city blocks. That is a lot of extra coax coiled up somewhere when you consider that all the coaxial cables are the same length. The whole tower is the antenna, that is, the whole 244-foot tower radiates the signal. The tower is not in direct contact with the huge slab of concrete that it is mounted on. There is a sort of plastic type cone that the tower is balanced on, which insulates it from the ground. There are also hundreds of ground radials consisting of #10 copper wire buried 1 foot below ground level, which make up the ground system as well as the other half of the antenna system. These ground radials fan out from the base of each tower in every direction of the compass. The ground radials also have to be all the same length, within a matter of inches. Each ground radial is the same length as the tower, 244 feet. That is a lot of wire when you multiply the hundreds of radials times 244 feet each. In addition to all these radials there is also a large 1 foot wide by ¼ inch thick copper strap connecting all the towers and going back to the transmitter building, which ties together the solid state transmitting gear cabinets, switch box cabinets, tuner cabinets, etc. Just about anything inside the building that is metal is connected to this ground strap. This copper strap is buried in the ground about 2-3 feet. One last thing about the antenna system. You might be wondering if such tall towers ever get struck by lightning. The answer is yes. The engineer told me that the ground system is so effective, that they have endured many lightning strikes with very little or no damage to the equipment. The lightning arrestor for each tower is ultra simple. It consists of a 12 inch long bar with a ball at the end. This bar is bolted to the bottom of each tower, and another 12-inch bar with a ball at the end is connected to the ground system. The balls at the end of each bar are about 1 inch apart. That is, the two balls have an air gap between them of about 1 inch. This air gap is the lightning arrestor. The air gap is small enough to cause a lightning strike to jump the gap and arc over to the ground system and be safely discharged. The air gap is large enough though that the transmission signal current would not jump the gap and be discharged to ground.

As I said earlier, the station engineer/electrician was a very friendly fellow. I did not get his name, but he told me a few things about himself. He does a bit of shortwave listening as well as ham radio listening. I believe he said that he owns a Hallicrafters S-30A receiver, as well as a Panasonic portable shortwave receiver. He also told a few stories about some reception reports that the station received. They have received several reception reports from the Scandinavian countries. He says that some of the Scandinavian listeners go up to the Lapland area for vacation and string out their 1,000 foot plus beverage antennas and monitor AM bands to try and log U.S. AM stations. One time the station sent out a nice goodies package to a Scandinavian listener that had sent in a taped reception report. The package included bumper stickers, t-shirts, etc. Soon after that, the station started receiving several taped reception reports from the same area. They were all exact copies of the first tape. These guys all got together and made duplicates of the original tape and submitted them as a supposedly valid reception reports, just so they could all get the same goodies package. It didn’t take the station too long to figure out what was going on, and promptly stopped sending out these packages to our fellow Scandinavian radio listeners.

I hope that you have enjoyed this report of my tour of WEJM radio. I did not ramble on too much did I? I found the tour to be quite interesting so I thought I would share it with you to the best of my literary capabilities.

2001 NOTES BY CHRISTOS RIGAS:

CALL LETTERS WNTD
FREQUENCY 950 kHz
OWNERS Radio Unica of Chicago                   
STATION ADDRESS Radio Unica
8400 NW 52^nd Street, Suite 101
Miami, Fl 33166

FORMAT Spanish language

TRANSMITTER

Daytime: Chicago, Illinois
Near Western Av. & 16^th St.
1 tower – 320 ft. tall
Power - 1,000 Watts

Nighttime: Burnham, Illinois
Near Torrence Av.
6 tower – 285 ft. tall                     
Power – 5,000 Watts

PREVIOUS CALLS WIDB, WEJM, WJPC