From Cuba with noise? Massive jamming on the 40 meter band.

Many thanks to SWLing Post contributor, 13dka, who shares the following guest post:

Massive jamming on 40m (possibly from Cuba) is bugging the radio community

by 13dka

Apparently this is going on for a week now on 40m:

Spent last night at my beach listening post on the German North Sea coast and found this fairly strong signal and a 40m band mostly cleared of any other signals. As soon as I found out that it wasn’t something local, I was wondering who’s responsible for this mess again. It looks like Josh (“Ham Radio Crash Course” YouTube channel) may have found a possible origin of that signal:

Here’s what it sounds like on each of the apparently manually controlled jamming channels:

Cuba would’ve probably been my last guess here on the other side of the big pond. 🙂 In other words, they – whoever they are – jam the band for at least half of the world. Luckily 40m isn’t exactly a pleasure in most of the summer anyway but after having to suffer OTH radars, FHSS blips and politically motivated broadcasting with associated jamming on 40m for a long time, this is a new low. I don’t want to get all political here but trying to erect some electromagnetic fence around a country has never really worked out, it’s just a futile, at most temporarily effective and symbolic act, perceived as pointless and aggressive vandalism out of blank despair by the rest of the world.


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25 thoughts on “From Cuba with noise? Massive jamming on the 40 meter band.

  1. Paul

    Hi thanks , the PL-660 goes back that far i was not aware of that at all , this new one is a nice portable after a 2 week of use all over the place , its bedside atm .
    A S-8800 is on the way as i type , i’ll decide if the S-8800 will eventually be permanent bedside or the FRG-100 here at the laptop , those decisions will be made after checking out the S-8800 and remote control , 🙂

  2. Jim, n4mxz

    These signals are identical in structure and around the same strength as the Cuban jamming of Radio Marti. This, and triangulation, leave little doubt that the source is Cuba. However, the assertion that they are specifically designed to prevent Cuban Hams from communicating with the outside world is absurd. The signals center at 7105, 7115, 7125, 7130, 7140, 7150, 7157, 7178, and 7215. Rumor to the contrary, they do not and have not moved. They are narrow enough that there is plenty of room for SSB and CW communications to take place. Further, I talked to a Cuban Ham in 15m on Wednesday, There is no jamming on 75m (open almost 24/7 to Florida), 20m or 15m., so it is not very effective. I don’t know what the Cuban gvt is up to, but it is not to prevent the handful (likely less than 20 total) of 40m Cuban hams from communicating on 40m.

  3. Desmond Walsh

    Is it true that the Cuban authorities have radio jamming installations near all cities and towns , similar to those in the ‘socialist ‘countries in Eastern Europe during the ‘Cold War’ era ? Supposedly they use what is called ‘an umbrella ‘ antenna ( widebanded fat vertical ?) so that all frequencies from bottom of medium wave to high HF can radiate jamming signals . A perceptive tourist in Cuban should be able to spot these installations. Surely by direction finding techniques the source of the 40m jamming signals should have been discovered by now ? We have enough rogue signals in the 40m band already .
    Des Walsh EI5CD

  4. Samuel Rhine

    I wonder if it is intentional though. Given how incompetent the government is at HF transmissions I wouldn’t be surprised if this was just another slip up. Hm01 for example has been a mess and slightly off schedule and dropping out a lot. I’ve seen their intentional jammers on non-Martí frequencies before and they look different and are much more powerful. As others have said this useless so my money is on a government LID.

    1. Mike Callahan

      Yes, it is intentional. I have been listening to shortwave since my youth and I’m 64 now. Back in the days of the old Soviet Union, jamming was commonplace. Governments are not incompetent. They just was people to believe they are. Another Cold War game is brewing now. As any knowledgeable person knows, a cold war can turn hot in the blink of an eye.

  5. PT

    TomL you’re obsessed with socialism. The problem is not that they’re “socialist” but that they’re corrupt. And the world has seen enough corrupt right-wing politicians to know that corruption can be found anywhere and everywhere.

  6. Tom Servo

    What I don’t get is why just target 40 meters, when there’s a whole plethora of other useful bands. 80m should work for making contacts in South Florida where many ex-pats and refugees have made their home. Even 20 meters could be useful in a pinch despite the poor solar conditions.

    I honestly don’t think Cuba has the ability to jam just any frequency on HF.

    1. W5OHR

      Cuban hams generally have 40 meter radios that were build many years ago. They don’t have the funds to buy commercial equipment. Also, the bounce of 40 meter band easy to get into areas of the US that have higher Cuban populations.

      The Coffee and Ham Radio YouTube show did a great job of explaining why 40 is being blocked by Cuba so heavily right now on Saturday.

      1. Tom Servo

        Thanks! That actually makes a lot of sense, W5OHR, although it does highlight the need for amateurs to be flexible in the face of adversity. With the resourcefulness of the Cubans in some many other aspects of their lives, I’m surprised they don’t have a backup plan for the loss of 40 meters.

    2. Samuel Rhine

      They do but it’s saved for blocking Radio Martí as well as jamming themselves (RHC/HM01) accidentally on occasion. I blame sloppy operations more than ill intent.

    3. Mike Callahan

      The 40 meter band is where a good bit of communications between the Ham Operators between Cuba and USA take place.

  7. Jay Bree

    Ah, the wonders of those progressive Socialist regimes! Nothing says “progressive” like censorship.

    This has gone on since the 60’s and the Cubans have been in the forefront of trying to block communications in and out of Cuba since.

  8. Steve

    I did an internet search for the Cuban consulate in Washington, D.C., and sent them an email expressing my displeasure with the blatant disregard for the free use of the radio spectrum. I encourage everyone to do the same.

    [email protected]


  9. Ivan - NO2CW

    40m is traditionally very busy at night here in South Florida and sometimes hams from PR, Colombia, Cuba, etc get in heated discussions. If you check out my kiwi receiver (NO2CW) you can see what 40m looks like now.

  10. Paul

    Be Damned if i could find a comment section for the Tecsun PL-660 , so its here 🙂 .
    New from ANON-CO this week , Firmware 6622 , build date 03/21 , pcb version REV.31 04/20 .
    No auto mute detected and i like this receiver , nice sound especially on SSB , BFO close enough , the 660 sounds just as good (nearly) as my dedicated HF radios , one needs an external antenna in for lower band receiving (below 5MHz as the whip is a very short antenna considering the Wave Length) , the telescopic whip does work but at a much reduced sensitivity .
    That’s it , a very happy chappie!

    1. Julio Cesar Pereira

      Thanks for the update on the PL-660. I also like the PL-660 a great deal. I had the auto mute deactivated on my unit. Since the PL-660 is not a DSP radio, a transistor is in charge of this infamous filter. A russian guy taught how to do it. This modification not only improved its reception but also its synch detect performance. As for the new version with the new firmware, I guess the only way to have it is to by a new PL-660, right?

      1. paul

        Yes the quickest and cheapest way for new firmware is a New Radio , personally i would not rush out to buy just for new firmware , but then again whats is wrong with a new radio 🙂 .

        I’m to order a New BCL S-8800 soon from Tecsun , Anna form Anon-co informed me that the build production run date on a new S-8800 is March/2021 , FW- H803 just for info btw .

    2. 13dka

      Yes this is the official PL-660 comment section. I really need to revisit mine once again before I give it away. It got only little action since I bought it in 2015 and even the protection foil is still on the display. 🙂

  11. Mark

    I saw this QRM on the waterfall that covers most of the 40 m band which only goes to 7.2 MHz here in Europe and as a consequence there was more activity above 7.2 Mhz.

    I still managed to get a contact in Oman over 4,000 miles from my with here in Ireland with just 100w and a Chameleon MPAS 2.0 just at the edge of the QRM where it wasn’t as loud but it was maki g dx harder for everyone.

    It’s a real shame, I don’t know why they do it but it serves no purpose when Cubans have the Internet to block some hams from communicating out that’s if it is from Cuba but all the evidence so far points that direction from using the kiwi sdr radios to triangulate the QRM.

    I expect no one will do anything about it because no one really cares about what? A million hams dotted across the planet who want to talk on a radio.

    40m has been plagued with QRM for a long time and it could be a way to force us off the 40 m band altogether.

    1. TomL

      Wrong, Internet was cut also. It was restored but not for social media links. This is how Socialist government works.

    1. TomL

      The Cuban Government does not want any free flow of information for its own people. Amateur radio operators were trying to read news items to Cuban citizens who have shortwave radios, and Cuban amateur radio operators were trying to tell others of eye witness accounts inside the country.

      Also, for a short period of time, the Internet was cut to the island which was finally restored many days later (but NOT social media links) – . Socialism knows no bounds to take away your freedoms, even if it does not make any sense.


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