KWTX-AM 1230

[radioguyntx]

Hi,

I was wondering if anyone knows anything about this station, I live about 15 miles away and I listen to it frequently and it fades out alot, other stations bleed through constantly. I don't really know anything about the technical aspect of radio transmission but have always been interested, and would love to learn more about it.

I thought about getting a better antenna to remedy the situation, but I can't really find anything out-of-the-box , and as I stated above, don't really know about engineering or building one. So if anyone would be willing to point me in the direction of a good website to read up on, or help me out I would greatly appreciate it.

 

[w9wi]

I was wondering if anyone knows anything about this station, I live about 15 miles away and I listen to it frequently and it fades out alot, other stations bleed through constantly. I don't really know anything about the technical aspect of radio transmission but have always been interested, and would love to learn more about it.

Day or night?

KWTX is a Class C station. That means that it, and all other stations on 1230, are protected from interference from each other during the day. At night, they're allowed to use the same power they use during the day - and it's assumed that since there's no daytime interference there will be no nighttime interference.

As you can tell by listening to any Class C frequency (1230, 1240, 1340, 1400, 1450, 1490) at night, that's not a very good assumption!

I would suggest the situation was created in the late 1920s/early 1930s when the FRC, later FCC, came into being. They were trying to reduce a really bad interference situation to manageable levels, and to do so without revoking the licenses of hundreds of law-abiding stations. They ended up dumping many of the smaller stations on "interference graveyards"...

 

[CW]

I was wondering if anyone knows anything about this station, I live about 15 miles away and I listen to it frequently and it fades out alot, other stations bleed through constantly. I don't really know anything about the technical aspect of radio transmission but have always been interested, and would love to learn more about it.

Day or night?

KWTX is a Class C station. That means that it, and all other stations on 1230, are protected from interference from each other during the day. At night, they're allowed to use the same power they use during the day - and it's assumed that since there's no daytime interference there will be no nighttime interference.

As you can tell by listening to any Class C frequency (1230, 1240, 1340, 1400, 1450, 1490) at night, that's not a very good assumption!

I would suggest the situation was created in the late 1920s/early 1930s when the FRC, later FCC, came into being. They were trying to reduce a really bad interference situation to manageable levels, and to do so without revoking the licenses of hundreds of law-abiding stations. They ended up dumping many of the smaller stations on "interference graveyards"...

The Class C channels have always been called backyards or graveyard channels...local usage and ok during the day..at night they USED to drop to 250watts....and could barely be heard outside of their COL....IF even that!...then the Commish (something about that word decided to allow Class Cs to use day power at night....NOW the noise on those channels is worse because of the number of stations clobbering each other...
Case in point...1450 in Beaumont (formerly KAYC) used to be heard in Port Arthur in the 70s (I was DJing on it then)...
and that was at 250watts out of the MW1....NOW??? 1450 out of Crowley LA ~100 miles to the east kills 1450 Beaumont in Port Arthur and Orange at night.....That's just wrong.....

 

[Mediafrog+]

The Class C channels have always been called backyards or graveyard channels...local usage and ok during the day..at night they USED to drop to 250watts....and could barely be heard outside of their COL....IF even that

Prior to the mid-60's the graveyard stations were 250 watts day and night. As for nighttime coverage in those days, I recall many of them would go about 15 miles before co-channel interference started ripping the signal apart, and about 20-25 miles before being completely lost in the noise.

Those stations did serve a useful purpose--covering a small or medium size town with a decent signal, from a simple single tower antenna running comparatively low power. Without the graveyard channels (which altogether contained around 1,200 stations 40 years ago) many communities would not have had AM radio in its heyday. The old Class A FM allotments served much the same purpose.

BYW, I recall being able to receive KWTX with a listenable signal in Austin (90 miles away) during the 60's.

 

[jd]

Looks like we need a little more info from radioguyntx, because reception at night could be pretty tough indeed if he's 15 miles away from the KWTX tower (about a mile NE of I-35 and Valley Mills).

On the other hand, from my post over on the "DX and Reception" board: "...as 'graveyard' stations go, KWTX in Waco has excellent daytime coverage. There are some areas in Texas with very high ground conductivity and that includes much of central and north-central Texas. In fact KWTX and co-channel KSST in Sulphur Springs can both be heard (individually or mixing it up) in many parts of the Dallas Fort-Worth Metroplex. (KWTX is almost 90 miles south of downtown Dallas; KSST is roughly 70 miles to the East-northeast.) Likewise KAND 1340 Corsicana puts a listenable signal into the downtown Dallas area, about fifty miles to the north."

 

[amfmhd]

KWTX has a 12.9 mV/m nighttime interference free contour. KSST and KEVR are the two biggest contributors to the night time interference. According to Commstudy, 12.9 mV/m goes about 9.6 miles. So you live outside the NIF contour and reception at night will be spotty.
You might try a nice loop antenna and see how that works.

 

[jd]

I take it you're referring to KERV in Kerrville?

 

[amfmhd]

yup

 

[radioguyntx]

What kind of info. you looking for? ....I live about 15 Mi. S.E. of Waco. (about 1.5 Mi. as the crow flies, from KBBW night-transmitters. I don't know how to make an antenna... But the main reason I posted is, I am interested in Broadcast engineering, and learning more... Thanks for the help.

 

[jd]

FWIW, 1010 + 1/2 of 455kHz (227.5) = 1237.5 kHz, just 7.5 kHz away from KWTX. Are you getting actual interference from KBBW or a strange whistle (heterodyne) just above KWTX?

 

[radioguyntx]

The best description I can give is it is like a high pitched whine, and also spanish and english voices wavering in and out at a fast pace.

 

[Ryan Williams]

The best description I can give is it is like a high pitched whine, and also spanish and english voices wavering in and out at a fast pace.

We carry no spanish programming at all. Can you make out any of the english?

Also, where are located in relation to the antenna farm?

Ryan Williams

PD/OD
KBBW (1010 KBW)

 

[slim101]

FWIW, 1010 + 1/2 of 455kHz (227.5) = 1237.5 kHz, just 7.5 kHz away from KWTX. Are you getting actual interference from KBBW or a strange whistle (heterodyne) just above KWTX?

jd,
I don't get the math here. Could you explain how that would cause interference?
All I can figure is that you are suggesting KBBW mixing with KWTX in the radioguyntx's receiver creating an mixing product (227.5) strong enough to have a second harmonic (455) strong enough to interfere with the desired signal. That doesn't seem likely with 1230 being 15 miles away.

Intermod is most often produced in the PA of one of the transmitters involved.
The most likely product is 790 khz from the KBBW tx ((2 X 1010) - 1230)) or 1450 khz from the KWTX tx ((2 X 1230) - 1010).

Seems more likely to me that he is hearing other stations on 1230.
If he is 15 miles away and the NIF only goes 9.6 miles he is in never-never-land as far as a signal free from skywave interference on 1230.

I would think that a good loop antenna is the (closest hope for a) cure, radioguyntx. Use it to null out the interfering stations, not maximixe the desired signal.

 

[jd]

Slim, it was just a guess on the IF possibility, considering how close he is to the KBBW towers, the high ground conductivity in the area and the chance of some quirk in his radio's circuitry. (IF's alone can and do cause problems but I'll admit the most common is the single and the 2X multiples, like I noticed a few years back in the Dallas area with 570 and 1480, which happen to be 910 kHz apart.) Strange things can happen, but your theory (and math) is probably more likely than mine...

 

[radioguyntx]

I have listened to 1010 and it comes in clear, and crisp.... and doesn't resemble any of the interference on 1230.
What may be a good loop antenna, as mentioned above I don't know any of the engineering aspects of radio, but want to learn more... Maybe I could build one? The only thing i find odd, is that I can go down the road about 3 miles and 1230 comes in clear again.

Radioguy

 

[CW]

I have listened to 1010 and it comes in clear, and crisp.... and doesn't resemble any of the interference on 1230.
What may be a good loop antenna, as mentioned above I don't know any of the engineering aspects of radio, but want to learn more... Maybe I could build one? The only thing i find odd, is that I can go down the road about 3 miles and 1230 comes in clear again.

Radioguy

If you live close to the other station, likely its signal is DESENSING your radio (caused by its carrier overloading the front end amp in your receiver).....A simple loop antenna can be bought at Radio Shack or other places but it has a short connecting cable...For outside and serious AM reception, look at the Belar Shielded loop antenna.. The loop operates in the magnetic instead of the electrical side...ALL radio signals have a E and M component...the electrical is usually stronger and easier to pick up with a simple whip or wire antenna..but the magnetic side (thought weak) is better because MOST noise is electrical and vertically polarized which a whip is and thus interfers with the E signal more easily. Also a loop is bidirectional...thus you can use that to null or notch the signal from a stronger station nearby while still getting the one you want (provided you dont live TOO close and you can even hear the desired signal in the 1st place; physics DOES has it limits!..and as "Scotty" often told Capt Kirk, you canna change the laws of physics!
Do a google search for AM shielded loops..you CAN built one BUT if your AM receiver does not have external antenna connections, you either must 1) modify the radio or 2) use a coupled amplified antenna like the one CC Crane sells (and I dont really like it)....

 

[radioguyntx]

My radio does have external output, i have tried putting up some 23 AWG strung up, but it doesnt work too well.... so i went back to the factory external loop antenna...

 

[CW]

My radio does have external output, i have tried putting up some 23 AWG strung up, but it doesnt work too well.... so i went back to the factory external loop antenna...

For that connection, it needs to be a tuned antenna. Just any old wire wont do as its not tuned or resonant...a loop antenna is and provides the chance to null out noise, etc while peaking on the signal...or at least a compromise...
Those antenna connections can work with coax or high impedance connections...but a good loop with proper connecions will probably give you the best.....Let me know what you decide and come up with.