When A Shortwave Transmitter Is Running Amuck

[SomeRadioGuy]

Radio Vision Missionaria in Brazil has 3 SW transmitters, one is on 11750khz with 2 or 5kw.. not sure

Well, one day the 11750 transmitter was running amuck. It was literally running and having amuck.
It was drifting as they broadcast and I'm not talking a few hz here and there. Im talking whole khz's and quickly.

Listen to my clip... you'll hear it all of a sudden go static. Then when it starts to drift and i dont catch it. And other times you hear that unmistakable sound when youre kind off tune, a khz or 2 and its kinda flat... and you hear me tune away and catch up with it.. back and forth, back n forth for 20 minutes.

RVM 11750khz 0304UTC Tue apr 29, 2025.mp3

drive.google.com

 

[Mediafrog+]

I just checked several online SDRs in Brazil, and Radio Voz Missionaria sounded “okay” on 11750. Modulation not great, but typical of the station. 9665 also on the air with similar quality, but the third transmitter on 5940 was off the air.

It was recently reported on SWDX forums that RVM had acquired a couple of secondhand shortwave transmitters from another broadcaster in Brazil. One of them was to replace their existing 5940 unit that had failed; the other would allow a power increase to 10kw on 11750. I have heard the 5940 transmitter via the SDRs recently, but it is missing today.

There are only eight domestic shortwave frequencies still active in Brazil: 5940, 9665 and 11750 from RVM, 6010 and 15190 from Radio Inconfidencia, 9819 from Radio Nove de Julho, plus the well heard 6180 and 11780 from Radio Nacional da Amazonia. The 2025 World Radio TV Handbook lists three other stations that are now apparently no longer on the air (no recent sign of them via the SDRs nor reported on SWDX forums).

Sixty years ago Brazil had around 200 domestic shortwave stations, so a typical story of the collapse of that platform.

RVM website is here: Rádio Voz Missionária - Sistema Gideões de Comunicação

 

[SomeRadioGuy]

I just checked several online SDRs in Brazil, and Radio Voz Missionaria sounded “okay” on 11750. Modulation not great, but typical of the station. 9665 also on the air with similar quality, but the third transmitter on 5940 was off the air.

It was recently reported on SWDX forums that RVM had acquired a couple of secondhand shortwave transmitters from another broadcaster in Brazil. One of them was to replace their existing 5940 unit that had failed; the other would allow a power increase to 10kw on 11750. I have heard the 5940 transmitter via the SDRs recently, but it is missing today.

There are only eight domestic shortwave frequencies still active in Brazil: 5940, 9665 and 11750 from RVM, 6010 and 15190 from Radio Inconfidencia, 9819 from Radio Nove de Julho, plus the well heard 6180 and 11780 from Radio Nacional da Amazonia. The 2025 World Radio TV Handbook lists three other stations that are now apparently no longer on the air (no recent sign of them via the SDRs nor reported on SWDX forums).

Sixty years ago Brazil had around 200 domestic shortwave stations, so a typical story of the collapse of that platform.

RVM website is here: Rádio Voz Missionária - Sistema Gideões de Comunicação

I've heard all of the Brazilian SW signals..

A friend and I refer to de Julho as "radio 9, 9819.xx whatever". Their modulation is in the terlet, always. Like Iran and Cuba. Theyre nto a regular, but theyre there from time to time..... quite often, just a carrier.

11750 is kinda common in the late spring through early fall. 9665 is very very common year round and in summer can be VERY Good. 5940 isnt very common.

6010 from R. Inconf. isnt too common at all, ever.. but its not impossible. I hear 15190 way better than youd think

6180 isnt too common in spring through fall, but it winter it can be heard here, not often too good, but now and then it can be good. It beams at 239 deg aazimuth, so it's going southwest ish to serve south america. 11780 is just banging.. i'm at the perfect location for a 2nd or 3rd hop and im only 18 degrees off the 312 deg azimuth dead center. I've become somewhat well known among listeners to the show "Eu de ca voce de la" because i regularly correspond on air using whatsapp voice notes and because the hosts english is self admitted to be very poor, ive learned several portuguese words to sprinkle into the conversation.

 

[Mediafrog+]

A friend and I refer to de Julho as "radio 9, 9819.xx whatever". Their modulation is in the terlet, always. Like Iran and Cuba. Theyre nto a regular, but theyre there from time to time..... quite often, just a carrier.

Modulation on 9819 was lousy but understandable at my SDR check this morning, which is typical. Often heard weakly direct here in Houston.

11750 is kinda common in the late spring through early fall. 9665 is very very common year round and in summer can be VERY Good. 5940 isnt very common.

9665 is the easiest for me to receive directly, but I can sometimes get a very weak signal on 11750. Have never heard 5940 direct, lost in the slopover from WWCR on 5935.

6010 from R. Inconf. isnt too common at all, ever.. but its not impossible. I hear 15190 way better than youd think

Not unusual to find one or both of those frequencies off the air during SDR checks.

6180 isnt too common in spring through fall, but it winter it can be heard here, not often too good, but now and then it can be good. It beams at 239 deg aazimuth, so it's going southwest ish to serve south america.

6180 was off the air at my SDR check this morning. Poor to fair direct reception when on.

11780 is just banging.. i'm at the perfect location for a 2nd or 3rd hop and im only 18 degrees off the 312 deg azimuth dead center.

11780 is a solid signal in Houston. This is the transmitter that has had all sorts of problems in the past few years…unit is from the 1970s.

 

[SomeRadioGuy]

Modulation on 9819 was lousy but understandable at my SDR check this morning, which is typical. Often heard weakly direct here in Houston.

9665 is the easiest for me to receive directly, but I can sometimes get a very weak signal on 11750. Have never heard 5940 direct, lost in the slopover from WWCR on 5935.

Not unusual to find one or both of those frequencies off the air during SDR checks.

6180 was off the air at my SDR check this morning. Poor to fair direct reception when on.

11780 is a solid signal in Houston. This is the transmitter that has had all sorts of problems in the past few years…unit is from the 1970s.

I can hear 5940 even with WWCR... often, theres at least minor slop over from WWCR.. somedays none.

Interesting, Eibi lists 11780 and 6180 as being on 0750 to 0300... but since the beginning of A24, theyve been signing off at 02. Some days, theyre so strong and steady, i can open my audio filters on my radio to 8khz and it sounds like FM Mono and im in the stadium watching the futbol match in person

 

[Mediafrog+]

Our friend in McGrath also posted this about the demise of another Brazilian on shortwave: Another One Bites The Dust In Brazil?!?!

 

[kevtronics]

The correct spelling is "amok", although the transmitter may indeed have some muck in it.

 

[sasha23]

I am somewhat off of Brazil's 11780 beam, so most of the time, strong to moderate signal with rapid fading.

6180 does not come in too well in the NE Illinois region, I wonder if that transmitter is on reduced power. Better reception in the fall/winter months, of course.

Wish that EBC would move 6180 down to at least 6175 so there's less interference to Mexico on 6185. When 11780 is really strong, 11750 (Radio Voz Missionaria) comes in alright S5/6 (when it's actually on the air)

 

[SomeRadioGuy]

I am somewhat off of Brazil's 11780 beam, so most of the time, strong to moderate signal with rapid fading.

6180 does not come in too well in the NE Illinois region, I wonder if that transmitter is on reduced power. Better reception in the fall/winter months, of course.

Wish that EBC would move 6180 down to at least 6175 so there's less interference to Mexico on 6185. When 11780 is really strong, 11750 (Radio Voz Missionaria) comes in alright S5/6 (when it's actually on the air)

11780 is 100 kw at 312 deg, which is NW, which on a 2nd and 3rd hope cuts right across the midwest us....based upon my reception and what ive seen from others..... i think youre after the 2nd but before the 3rd hop.

Im 12 degrees off dead center from 11780

6180 is 100kw at 239 degrees, which is SW of them, hitting south America.

 

[sasha23]

11780 is 100 kw at 312 deg, which is NW, which on a 2nd and 3rd hope cuts right across the midwest us....based upon my reception and what ive seen from others..... i think youre after the 2nd but before the 3rd hop.

Im 12 degrees off dead center from 11780

6180 is 100kw at 239 degrees, which is SW of them, hitting south America.

where did you obtain beam info.?
short-wave.info has 0/344 degrees respectively.
possibly that site is somewhat inaccurate like radio-locator lol

at any rate, the signals for either at my location in Northern Illinois are almost always fluctuating considerably.

when I tune in on an SDR closer to the east or west coasts, the signals are usually more steady. likely the takeoff angle on their curtain arrays have been designed to hit northern/western Brasil, which would make sense.

I don't think that EBC ever really followed through to be an international broadcaster, even though they were at one type equipped to do so.

I remember reading somewhere that at one time EBC had 4 high power transmitters, and their curtain arrays were at least capable of targeting at least S/N/C America, Caribbean and Europe...now only 2 tx working with 11780 seems to be the most reliable

wonder what happened to their experimental DRM transmissions...did anyone hear these?

 

[Mediafrog+]

I don't think that EBC ever really followed through to be an international broadcaster, even though they were at one type equipped to do so.

I remember reading somewhere that at one time EBC had 4 high power transmitters, and their curtain arrays were at least capable of targeting at least S/N/C America, Caribbean and Europe...now only 2 tx working with 11780 seems to be the most reliable

Brazil did have a modest multilingual international service in the 1980s and 90s. Scheduling was sometimes a bit difficult to figure out, IIRC, but signal levels into Texas were decent. Would have to dig into some old WRTH editions from that era for more details; the station was never a major player and my memories of it are a bit fuzzy decades later.

wonder what happened to their experimental DRM transmissions...did anyone hear these?

I could hear the “digital roar” here in Houston (frequency was 11910 kHz IIRC) but I don’t have any DRM decoding capability. There were some North American DXers who were able to decode audio.

Haven’t heard anything lately about where EBC’s DRM plans are going, assuming they still have any.

 

[Patrick 29582]

where did you obtain beam info.?
short-wave.info has 0/344 degrees respectively.
possibly that site is somewhat inaccurate like radio-locator lol

at any rate, the signals for either at my location in Northern Illinois are almost always fluctuating considerably.

when I tune in on an SDR closer to the east or west coasts, the signals are usually more steady. likely the takeoff angle on their curtain arrays have been designed to hit northern/western Brasil, which would make sense.

I don't think that EBC ever really followed through to be an international broadcaster, even though they were at one type equipped to do so.

I remember reading somewhere that at one time EBC had 4 high power transmitters, and their curtain arrays were at least capable of targeting at least S/N/C America, Caribbean and Europe...now only 2 tx working with 11780 seems to be the most reliable

wonder what happened to their experimental DRM transmissions...did anyone hear these?

Same here in coastal SC. 11780 easily the strongest signal on the band most nights. 6185 trace of signal mixed with 6180.

 

[sasha23]

Same here in coastal SC. 11780 easily the strongest signal on the band most nights. 6185 trace of signal mixed with 6180.

are you saying that 6185 Mexico is mixing with Brasil 6180? I am hearing both well separately, actually Mexico has better modulation than Brasil. 11780 is modulated much better than 6180.

 

[SomeRadioGuy]

are you saying that 6185 Mexico is mixing with Brasil 6180? I am hearing both well separately, actually Mexico has better modulation than Brasil. 11780 is modulated much better than 6180.

Not even close on 6185 vs 6180

The modulation is awfully low all the time on 6185.To the point sometimes atmospheric noise and static take it out up here. 11780 and 6180 are just fine.

 

[Patrick 29582]

are you saying that 6185 Mexico is mixing with Brasil 6180? I am hearing both well separately, actually Mexico has better modulation than Brasil. 11780 is modulated much better than 6180.

They mumble along equally here. I can barely identify the program as matching 11780, with a narrow filter.

 

[SomeRadioGuy]

They mumble along equally here. I can barely identify the program as matching 11780, with a narrow filter.

Not even close here.. i think the problem is signal not audio.. 6180 beams at 239 deg towards south america, 11780 is at 312 deg

 

[Patrick 29582]

Not even close here.. i think the problem is signal not audio.. 6180 beams at 239 deg towards south america, 11780 is at 312 deg

Yes the 11780 is ideal for Eastern NA. 6180 much less so.

 

[SomeRadioGuy]

Yes the 11780 is ideal for Eastern NA. 6180 much less so.

Obviously so, for reasons I just pointed out. 11780 is GREAT here.. never had modulation issues