INTERFERENCE FROM A PHANTOM CARRIER

  • 1
  • Question
  • Updated 10 months ago
THERE IS A STRONG CARRIER SIGNAL THAT WILL DRIFT DOWN IN
FREQUENCY THAT CAN BE HEARD OVER THE WHOLE SECTION IN
THE UPPER PART OF THE 75 METER HAM BAND, MAN-MADE BUT NOT
INTENTIONAL, ANY IDEAS? I CAN WATCH THEM START ON THE
PANADAPTOR JUST ABOVE 4 MHZ AND TREND DOWN. I HAVE ALSO
WATCHED THE SAME ABOVE THE 40 METER BAND. AND NO I'M NOT
SHOUTING.

73, JIM N9VC
Photo of N9VC

N9VC

  • 107 Posts
  • 28 Reply Likes

Posted 10 months ago

  • 1
Photo of Dave KD5FX

Dave KD5FX

  • 83 Posts
  • 4 Reply Likes
I've seen that from a 'smart' battery charger for my car. Also, the charger for my drill does about the same thing but not as strong of a signal. Check your whole house for ANY kind of battery charger, unplug them all and see if the problem goes away.
Photo of N9VC

N9VC

  • 107 Posts
  • 28 Reply Likes
Thanks Dave, but that is not it. Stations within Wisconsin spread over a many mile radius
can hear it. It varies in amplitude as it is drifting across the spectrum. It can start around
4025 KHz or such and go down slowly to maybe 3970 KHz or such. And all are hearing the
same signal drift. If it were at my QTH. it would be super strong and less amplitude to the
stations 80-90 miles away. And again it varies as it drifts from S1 to S8 or 9. If it were as you
say, it would be a constant amplitude. I had thought things like a oscillator from a satellite
with doppler, but sometimes it can reverse. I also thought weather radar installations.
It can vary where it might stop in that range. Sometimes it can stop around 3990 KHz or
there-about. I do not believe it is intentional. Just a head scratcher.

73, Jim N9VC 
Photo of N9VC

N9VC

  • 107 Posts
  • 28 Reply Likes
It sounds like a space ship from the old science fiction movies taking off.

73, Jim N9VC
Photo of Tim - W4TME

Tim - W4TME, Customer Experience Manager

  • 9052 Posts
  • 3435 Reply Likes
"AND NO I'M NOT SHOUTING."

Studies have been conducted on the readability and legibility of all caps text. Scientific testing from the 20th-century onwards has generally indicated that all caps text is less legible and readable than lower-case text. In addition, switching to all caps may make text appear hectoring and obnoxious for cultural reasons, since all-capitals is often used in transcribed speech to indicate that the speaker is shouting. All-caps text is common in comic books, as well as on older teleprinter and radio transmission systems which often do not indicate letter case at all.

https://en.wikipedia.org/wiki/All_caps
Photo of Phil - WG5D

Phil - WG5D

  • 39 Posts
  • 3 Reply Likes
Upper case letters also slows down PSK31 traffic as lower case text in PSK31 varicode transmits fewer bits of data - just sayin' :)
Photo of N9VC

N9VC

  • 107 Posts
  • 28 Reply Likes
All right, I'm sorry. OK?
Photo of Ken - NM9P

Ken - NM9P, Elmer

  • 3875 Posts
  • 1180 Reply Likes
Some of my buddies that hang at 3.817 MHz +/- from 8-10 pm eastern have noticed a similar carrier in Michigan, Indiana, and surrounding states.  It isn't every day, but sporadically re-occurs.

We can watch it on our Flex panadapters as it will appear, drift down and through our bandwidth, and then disappear after a few minutes, only to do it again a few minutes later.

The running theory is that someone in a 75 Meter Rag Chew group has an amplifier that is not properly neutralized, and is generating parasitic oscillations when it is his "turn" in the round table.  It likely is an old timer who foot switches it, because if he used VOX it would come and go very quickly.

Any other theories?

Ken - NM9P
Photo of N9VC

N9VC

  • 107 Posts
  • 28 Reply Likes
Thanks, Ken. That has possibilities. That could account for the same type of
thing I see above the 40 meter band. Possibly the second harmonic. I will have
to open a couple of panadaptors to get an idea and comparison of the drifting
signal and when someone has a transmission on the 75 meter band. Compare times and duration. Thanks.

73, Jim N9VC
Photo of Rory - N6OIL

Rory - N6OIL

  • 251 Posts
  • 46 Reply Likes
Fire up some of the web sdr's and watch them.
Photo of Norm - W7CK

Norm - W7CK

  • 745 Posts
  • 151 Reply Likes
Haarp?   I know they are back on the air.  Not sure if they would be able to focus on such a small geographical area all the way from Alaska or not.
Photo of Rich McCabe

Rich McCabe

  • 975 Posts
  • 211 Reply Likes
I have found with  a house full of poorly built electronics (common these days) our noise is often coming from inside the house. Every time I rearrange my shack I have new issues I have to deal with. Power supplies for electronics are terrible which is why I try to run everything in the shack off a large transformer type Astron.

I probably have 50 pounds of torroids in my radio room.