AM Radio Stations

[Jeffhs]

Originally Posted by NowhereMan 1966

I've noticed some of the same thing here in the Pittsburgh area. Mom likes to listen to KDKA-AM in the morning and sometimes I hear in the signal some interference like someone firing up a diathermy machine or a heavy motor. Come to think of it, KDKA's signal isn;t as great at time since they switched to the new 1994 antenna and retired their 1937 one. They should have kept the latter.

When I lived in suburban Cleveland, 18-20 miles east of the city, I had excellent AM reception, but one station in particular (50kW then-WGAR-AM 1220) would come in louder than normal whenever I would pass by a pole that supported the school speed-limit sign (I lived near an elementary school at the time). I've always wondered why. The only explanation I can come up with that makes any sense to me is that I may have been directly in line with the station's daytime signal pattern when I walked near that pole. I did not notice this, however, with the other 50kW station in Cleveland (then-WKYC-WWWE-AM, now WTAM 1100) or with any of the smaller stations (Cleveland has a handful of 5kW stations, one 1kW station, and a bunch of stations 1kW or less in the suburbs).

I was not aware that KDKA-AM had changed antennas in the mid-'90s. What happened? Did the old tower come down in a storm? If the original antenna tower had been up since 1937 (57 years), it may have been due or even overdue for a change.

KDKA-AM, like most 50kW AM stations these days, must share its frequency (1020 kHz) with smaller stations, in accordance with new FCC rules that did away with clear-channel AMs (and allowed former daytime-only stations to operate full-time under certain conditions) in the mid-1980s. It may be, since KDKA is no longer a "clear channel" station, that its signal isn't as strong during the day as it once was; at night, the station may have to reduce its power output and/or change its signal pattern so the latter is directional (concentrating the signal in one direction). The station may be running directional during daytime as well.

How far are you from KDKA's transmitter? If you are some distance away, the signal could be weak to begin with; any interference could chop up or even mask it entirely.

Interference to AM radio is a real problem these days, even more so than it was, say, 25 years ago. Today we have cellular telephone towers, pager towers, police radio, etc. all operating at the same time. If you are near any of those towers, your AM radio reception could and likely will be riddled with noises; the noise you report on KDKA's signal that sounds like diathermy could be interference from a nearby cellular or pager transmitter.

Noise levels in apartment buildings are often high as well. I live on the first floor of a 2-story building; my AM reception is often marred by noise, especially on my Zenith C-845. I oftentimes cannot hear a 50kW sports station on 850 or a talk station on 1100 because of the high noise levels. The problem is especially bad when listening to AM on my C845 because the radio has a 6BJ6 RF amplifier that works for both bands, AM and FM; the tube winds up amplifying everything the antenna picks up, including the signals. The irony is, IMHO, that there is no noise whatsoever on FM on any of my vintage radios. Being a ham radio operator, I ought to know why: because AM signals are much more prone to interference from sparking brushes in motors, microwave ovens, etc. than are FM signals. FM is almost completely immune to noise interference, which may be yet another reason why hit music left AM and migrated to FM. It was probably the best thing that ever happened to vintage and classic rock, not to mention classical music.

BTW, I was very sorry to hear (have read in one of your posts) that another of your cats has passed away. I know the feeling, as I had to have my first white cat, Shawn, put to sleep in 2002 (he was in the last stages of severe liver damage at the time, according to the vet). My second cat, Jonah, also pure white and looking exactly like Shawn, however, is doing very well. He's sleeping on the floor about three feet behind me as I write this.

Seventeen years is a very long life for a cat. I'm sure both Pansy and Boo have left you with tons of nice memories. I know my Shawn did, and Jonah will too, when the day comes (heaven forbid) that he either dies on his own or I have to have him put to sleep.

Just remember all the good times you had with Boo and Pansy, and you'll be just fine. If I remember correctly, you still have several other cats around, so you'll have their company for at least a few more years.