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Terrible noise on HF SSB

Feb 17, 2006
5,078
Lancer 27PS MCB Camp Pendleton KF6BL
I went to the boat today to do some work on my SSB and my outboard. The outboard will not go up or down. It is electric trim and I found out that a lot of wave action a few months back cause the marina's rentals to do some what of the same thing. So I think it is salt build up that is causing that issue. OK, enough about the outboard.

I get to the boat and start working on the outboard. When I finally decided I need to do something else about the outboard I move instead to the SSB radio. While working on the outboard, this beautiful RIB belonging to Homeland Security with three heavily armed guys pulls in. This is a Military Marina so there must be some kind of agreement for them to park there. I looked around but did not see S/V Drama Queen anywhere. So I went about my business.

I turned on the radio and this is what I hear:

First thoughts are the Solar Charger and/or the battery charger. I turn them off and the noise did not go away. So I made a video for the purpose of sharing and seeing if anyone could identify the noise. It is pulsating so it must be radar. I could see many boats with radar but they are just sitting there. Maybe military radar, but I don't see any in sight. So it has to be something on my boat that is causing the noise. Disconnect the antenna and noise is gone, so proof positive it is outside interference.

I then poke my head up and look around one more time. The Homeland Security boat. Let me go ask. So I walk over and explain very politely about the noise. I explain I am a Ham and use SSB on my boat. I asked them if they had anything that was running, but I also tell them not to answer that question. (They smiled) Their radar was not running, but one guy said their AIS was active. So I feign surprise and said I never thought of that. Key opportunity to shut down their electronics and they volunteered to do just that.

Noise gone! How about that?

So feigning disbelief I ask for them to power up their "AIS" again. They did, but no noise. Even more interesting.

OK, time for them to depart and just as they were backing up... BANG! there is that noise again.

Lesson learned here, guys. If you have HF SSB and you start to hear the noise in the video look around for an armed HomeLand Security boat moving up on you, or near you, or in the area and I mean close like around 100ft.
 
Sep 25, 2008
6,265
Alden 50 Sarasota, Florida
Their sonar generates sound waves, not broad band RF and neither should anything else they have aboard as it could cause similar noise to their VHF-UHF stuff.

The mystery continues...
 
Feb 17, 2006
5,078
Lancer 27PS MCB Camp Pendleton KF6BL
If it was sonar, it would have to have a carrier component in the HF radio band. Specifically 14 MHz (14,000,000 Hz). So I would agree with Don. However, since I am not knowledgeable in newest technology for the military, I don't know. All I do know is it was pulsating. If you slow the video down, one could probably count the pulse rate.
 
Feb 17, 2006
5,078
Lancer 27PS MCB Camp Pendleton KF6BL
@JimInPB, that could be possible but I believe cell phone jamming is illegal in the US. Now having been in Afghanistan I have seen the cell phone jammers to prevent activation of an IED. But I have not "heard" what the signal would sound like. But I don't think it would be a pulse. It would be just a broadband carrier in the cell phone frequencie bands.
 
Oct 19, 2017
6,875
O'Day 19 Littleton, NH
How about an ordinance scanner? Maybe looking through and at the bottom of hulls?

- Will (Dragonfly)
 
Feb 14, 2014
5,617
Hunter 430 Waveland, MS
That was 2 separate points.

1) The harmonics from different frequencies beside 14.3.
2) Antennae type, might indicate amplification or polarization of the repetitive signal.

Jim...

PS: Antennae do absorb radiation too.;)
 
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Feb 17, 2006
5,078
Lancer 27PS MCB Camp Pendleton KF6BL
Half-wave dipole. I guess one could start adding harmonics to try and find the fundamental frequency. I did slow the video down and determine the pulse was at 11~12 Hz. I also tried to find audio files of depth sounders and fish finders, but I could not find any. If this is a new technology then they have issues because it is leaking like a sieve.
 
Feb 14, 2014
5,617
Hunter 430 Waveland, MS
Just a wild thought...
Any small animal electric fencing or "hidden" dog boarder RF fencing nearby. They use "pulsed" DC.

I assume your dipole is almost vertical, classically used for the 40 meter band.

12Hz pulsing is not sonar.

Did the interference disappear when DHS boat left?

Which Side Band was your radio tuned to, or is it automatic notch filtering?
Jim...
 
Feb 17, 2006
5,078
Lancer 27PS MCB Camp Pendleton KF6BL
No electrical fencing that I know of.
Dipole is near vertical. Top of mast to stern.
Yes, as soon as the DHS boat left, the interference went with it.
USB, no notch filtering. This radio is too basic and simple (Icom IC-707)
 
Sep 25, 2008
6,265
Alden 50 Sarasota, Florida
No electrical fencing that I know of.
Dipole is near vertical. Top of mast to stern.
Yes, as soon as the DHS boat left, the interference went with it.
USB, no notch filtering. This radio is too basic and simple (Icom IC-707)
None of that would be relevant. It's probably nothing more than a dysfunctional outboard charging circuit.
 
Feb 17, 2006
5,078
Lancer 27PS MCB Camp Pendleton KF6BL
When they pulled up, they shut down their motors (4x350HP). I detected the noise way after they arrived. So we can eliminate outboard spark noise.

It really isn't important, just a WTF moment on HF.
 
Oct 19, 2017
6,875
O'Day 19 Littleton, NH
I'm still waiting for a knock on my door.
Do you keep Kryptonite on your boat? That's why it's important to extend the lead from your keel up into the bilges. Don't want the kryptonite radiation to leak out. If you were anywhere near Bursledon City during their regatta, you might have been scanned in preparation for Superman's appearance.

Got to keep the guy in the blue tights safe.

-Will (Dragonfly)