ECN Forum Forums General Topics of the Trade General Discussion Area AM Radio?

Paul,

I can give a little reference to AM broadcast stuff right now, and reply later with more detailed info.

Commercial AM radio broadcasts spectrum range = 540 kHz to 1.6 mHz.
Channel Size = 10 kHz (example: 540, 550, 560, etc.)
Bandwidth = 5 kHz (5 kHz of audio max.)
Envelope (Signal Composition): Double Sideband Full Carrier Signal (LSB / Carrier / USB).

The 5 kHz max. for audio information results in the "Muddy Mid-Range Only" sound, which drives me crazy!!!
The ease of atmosphere noise falling in, and being included with the audio information, is "Too Much B.S." for me to tolerate

Let me see what the books say!

Scott35 S.E.T.

Yes, they've been the standard specs for decades. Wasn't there talk of extending beyond 1600kHz to squeeze in some extra low-power local channels? Not much use for those with a receiver which won't tune up high enough!

AM broadcast here has become much more noisy over the years. The plethora of stations that have sprung up all over the U.K. and Europe coupled with horrendous levels of wideband interference from computers and all the other modern gadgets means that listening to anything other very strong local signals results in a lot of heterodyning and other assorted crackles, whistles, and noises.

The MW band extension to 1700 kilocycles was done in the late 80s/early 90s.

Not all that many stations have moved there....besides you would only have room between 1600 and 1700 for maybe two stations

The warped (IMHO) reason for that extension was not to place new stations, but to move existing very low power stations to the new part of the dial where they could broadcast with higher power (10,000 watts daytime; 1,000 watts nighttime) and using a non-directional antenna.

The licence for the "old" station would be turned in after 5 years of the new "expanded band" station going on the air and would be deleted permanently.

Unfortunately things have changed.

Waivers have been granted and now in New York City we have a station on AM 1660 (WWRU) that broadcasts with 10,000 watts daytime and night-time and uses a directional antenna at night.

The stations may also be sold separately, which means the "old" station that would have been deleted continues to stay on the air in addition to the new station on the "expanded band".

Also, you may see some cheap radios where the dial goes up to 1700khz but the tuner mechanism is such bad quality that the radio may not tune up that high, or if it does it will start drifting off station. Had that problem with a small Philips pocket radio I bought brand new a couple of years ago.

The space between 1600 and 1700 is THE WORST place for an AM station to be.

[This message has been edited by SvenNYC (edited 01-31-2003).]

Just a small question,
someone mentioned AM Stereo, this was mooted as a competitor to FM, when it was first brought out, tell me, did it ever take off where you are?, I've heard that it is used quite prolifically in Australia, we never got it over here in NZ, though, the broadcast authorities, thought it to be a waste of money.
It apparently has better Frequency Response
than standard AM Mono, is this true?.

Although I don't share Scott's dislike for AM 640 KFI:
They are a "Clear Channel" station, meaning no other station shares their frequency.(hence the 3 letter designation KFI).
50,000 watts of power, they occupy the CONELRAD (remember the old triangles on your radio?) frequency.
They are our best emergency station, and don't worry, they come through...they covered the 9-11 well.
I've even got KFI in Wichita, Kansas (conditions were right?)
In an emergency, they kick butt ...S

Electure,

The three letter call sign has nothing to do with the channel designation.

It is merely a VERY old station...the first call signs given out by the Federal Radio Commision (predecessor to the FCC) used three letters (KHJ Los Angeles, KYW Philadelphia, WBZ Boston, WOR New York, WLS Chicago).

Some famous "clear channel" (not to be confused with the company of that same name) stations with four letter call signs that have been around forever are WABC New York, WEAF (defunct) New York, KABC Los Angeles, KIRO Seattle, WMAQ (defunct) Chicago.

The FCC no longer assigns three-letter calls. However in special cases, they will let you get your original three-letter call sign back if you happen to own the curent station at that exact dial position.

This happened a couple of years ago with KHJ/Los Angeles which had switched to KKHJ and then was permitted to change back to KHJ.

The reason was (and I'm not joking) because KKHJ was a Spanish statoin and management said that if you said the call letters in Spanish it would sound like this: KA KA ACHE JOTA (hard J).

In Spanish, KA KA (actually written caca) is slang for feces. So you get the idea.

So now the station IDs itself as KA AHCHE JOTA (hard J)

Sorry.....I'm a radio geek...so this is one thread that got me hooked

Ooops.
Again my foot is in my mouth Sometimes I'm a fountain of misinfo.

Interesting thing about 93 KHJ, they were very progressive in the 60's. I heard an interview with an "new,unknown" artist that played very odd music....Jimi Hendrix.

The KFI tower is just a few miles away, and yes, it's VERY old. I'll try to get a pic.
I've got 3 customers within about 2 blocks of it. One, next door to it, has nearly every fastener in the place tack welded, but was that the doing of some crazy engineer? Nothing else in the area has loosened up.
BTW, I heard long ago that Lucille Ball got KFI on her tooth fillings. Is this just another myth??...S
PS Sorry, there's no hard J in Spanish, but yes, the letter comes very close to another Spanish word for homosexual.
How about car names: Chevy Nova= No Va=No Go,
and the Ford Pinto didn't fare too well in Argentina where it's a slang term for genitalia



[This message has been edited by electure (edited 02-01-2003).]

electure,

Sorry for that.

I meant an English H sound when pronouncing 'jota' - as in "hoe-tah" (so one doesn't confuse it with joe-tah) - the sound of getting phelgm caught in your troat after a cold...

In Spanish, when used in a word, the H is silent (ex. hotel is pronounced O-tel)

One of the problems with AM is the local oscillator of 455kHz if you are in a bad area where skips are present, you can pick up the same station on the lower end at multiples of the 455. If for instance in our area local AM station is 570 it can be picked up at about 1025 and again at 1480, Or sometimes, KDKA ou of Pittsburgh is 1020 that can be had on the lower end if atmospherics are right.
But with skips AM can be picked up all over the world where FM is almost line of sight.
In the Mediterranean(SP) we were able to WLS out of Chicago with a cheap transistor radio.
But as Scott said the guardbands on FM are great for getting rid of interference especailly locally.

WOC

Trumpy:

Re: the AM Stereo--I don't know if KYW still broadcasts in Stereo. I don't have a clue if AM Stereo ever made a big wave...