Every so often, I revive my interest in shortwave listening. So, I just built an S-meter for my Hallicrafters S-40B. (My S-meter is essentially just an ammeter that measures the plate current of the first RF tube, which is controlled by AVC - the lower the plate current, the higher is the relative signal strength.)

For the first time, I'm noticing a few very strong SW "stations" that are just carriers, no audio modulation. Based on their exceptional strength and lack of any fading, I suspect the transmitters are in North America somewhere. Without my S-meter, I would have tuned right past these without giving them any thought whatsoever. Without an S-meter, it's just a narrow, totally quiet frequency.

I can imagine why a SW station may want to get its transmitter warmed up before starting a broadcast, but I don't think that is it.

It seems like I read somewhere about this phenomenon, and one theory involved the CIA? Maybe the blank carrier is a "placeholder" for future broadcasts if something special happpens somewhere around the world? Or maybe just a regular SW station, staking claim to its frequency when it's off the air? Or perhaps just somebody doing signal strength tests (e.g., Can you hear me now?) without bothering to modulate?

Can anybody shed any light on this?

I'm thinking about hooking up a recorder, activated by any audio modulation, to see if the "stations" ever identify themselves.
Doug

:Every so often, I revive my interest in shortwave listening. So, I just built an S-meter for my Hallicrafters S-40B. (My S-meter is essentially just an ammeter that measures the plate current of the first RF tube, which is controlled by AVC - the lower the plate current, the higher is the relative signal strength.)
:
:For the first time, I'm noticing a few very strong SW "stations" that are just carriers, no audio modulation. Based on their exceptional strength and lack of any fading, I suspect the transmitters are in North America somewhere. Without my S-meter, I would have tuned right past these without giving them any thought whatsoever. Without an S-meter, it's just a narrow, totally quiet frequency.
:
:I can imagine why a SW station may want to get its transmitter warmed up before starting a broadcast, but I don't think that is it.
:
:It seems like I read somewhere about this phenomenon, and one theory involved the CIA? Maybe the blank carrier is a "placeholder" for future broadcasts if something special happpens somewhere around the world? Or maybe just a regular SW station, staking claim to its frequency when it's off the air? Or perhaps just somebody doing signal strength tests (e.g., Can you hear me now?) without bothering to modulate?
:
:Can anybody shed any light on this?
:
:I'm thinking about hooking up a recorder, activated by any audio modulation, to see if the "stations" ever identify themselves.
:Doug

Doug:
I would try disconnecting tha antenna to be sure that you are not picking up harmonics of the local oscillator, then turning off things in the house that might use microprocessors, such as cable boxes, computers, monitors, microwave and stove clock, set back thermostat, etc. There are many things around my house that transmit weak signals that drive my scanner nuts. Your "CIA" broadcasts may be closer than you think.

Lewis L.

OK, Lewis, I'll try to check this out further, with an open mind. But I'm still thinking there is something to this, really. Usually, don't local oscillators normally show up as birdies, not silent carriers? But, all I said was that the source was in North America, right?

Actually, I do have a solid-state multi-band radio with completely different IFs, so I can use that as a double check.

But also, I want to tell you about the microchip that I think the CIA may have implanted into my skull and also one maybe in my rectum! :>)
Doug

:
:Doug:
:I would try disconnecting tha antenna to be sure that you are not picking up harmonics of the local oscillator, then turning off things in the house that might use microprocessors, such as cable boxes, computers, monitors, microwave and stove clock, set back thermostat, etc. There are many things around my house that transmit weak signals that drive my scanner nuts. Your "CIA" broadcasts may be closer than you think.
:
:Lewis L.

:But also, I want to tell you about the microchip that I think the CIA may have implanted into my skull and also one maybe in my rectum! :>)
:Doug

What do you mean "think" and "MAY HAVE"....???...
mine's been in a long time and working just fine.
.. %*$#$#&^% ...what was that ?

Peter, I have a friend who is a doctor at the Mayo Clinic in Rochester, MN. A female patient was in for a physical, which included a sygmoidoscopy. Soberly and matter-of-factly, she told the doctor to watch out for a chip in her rectum that had been implanted there by the CIA.

Naturally, she was quickly referred to the psychiatric department. True story, not an April Fool's joke.

In my opinion, doctors should always keep a few TTL chips handy. When presented with a similar situation, they would pull one out of the drawer, and say, "Oh, here it is - I've removed it!"
Doug

:
::But also, I want to tell you about the microchip that I think the CIA may have implanted into my skull and also one maybe in my rectum! :>)
::Doug
:
:
:What do you mean "think" and "MAY HAVE"....???...
:mine's been in a long time and working just fine.
:.. %*$#$#&^% ...what was that ?
:

The "Mayo" clinic?

I prefer mustard.

OK, I've rechecked things. A strong, unmodulated "carrier" is at 3020 kHz. I have verified that it's originating inside the house, but I haven't yet been able to pinpoint the exact source - because it seems to radiate over the electrical wiring. It's definitely not the local oscillator of any of the four different radios that pick it up.

I'm going to have to shut down all my electrical branch circuits, and bring them up one at a time to find the source - but not today.

So maybe I was a little hasty in suspecting the CIA...unless, of course, they have bugged my house! Hmmm.
Doug

Doug

::Every so often, I revive my interest in shortwave listening. So, I just built an S-meter for my Hallicrafters S-40B. (My S-meter is essentially just an ammeter that measures the plate current of the first RF tube, which is controlled by AVC - the lower the plate current, the higher is the relative signal strength.)
::
::For the first time, I'm noticing a few very strong SW "stations" that are just carriers, no audio modulation. Based on their exceptional strength and lack of any fading, I suspect the transmitters are in North America somewhere. Without my S-meter, I would have tuned right past these without giving them any thought whatsoever. Without an S-meter, it's just a narrow, totally quiet frequency.
::
::I can imagine why a SW station may want to get its transmitter warmed up before starting a broadcast, but I don't think that is it.
::
::It seems like I read somewhere about this phenomenon, and one theory involved the CIA? Maybe the blank carrier is a "placeholder" for future broadcasts if something special happpens somewhere around the world? Or maybe just a regular SW station, staking claim to its frequency when it's off the air? Or perhaps just somebody doing signal strength tests (e.g., Can you hear me now?) without bothering to modulate?
::
::Can anybody shed any light on this?
::
::I'm thinking about hooking up a recorder, activated by any audio modulation, to see if the "stations" ever identify themselves.
::Doug
:
:
:Doug:
:I would try disconnecting tha antenna to be sure that you are not picking up harmonics of the local oscillator, then turning off things in the house that might use microprocessors, such as cable boxes, computers, monitors, microwave and stove clock, set back thermostat, etc. There are many things around my house that transmit weak signals that drive my scanner nuts. Your "CIA" broadcasts may be closer than you think.
:
:Lewis L.

:OK, I've rechecked things. A strong, unmodulated "carrier" is at 3020 kHz. I have verified that it's originating inside the house, but I haven't yet been able to pinpoint the exact source - because it seems to radiate over the electrical wiring. It's definitely not the local oscillator of any of the four different radios that pick it up.
:
:I'm going to have to shut down all my electrical branch circuits, and bring them up one at a time to find the source - but not today.
:
:So maybe I was a little hasty in suspecting the CIA...unless, of course, they have bugged my house! Hmmm.
:Doug

Have someone monitor your receiver while you stomp around and whistle or sing in all the rooms of your house. Of course, you might want to wait until all your neighbors are asleep. :>)

Lewis L.

::OK, I've rechecked things. A strong, unmodulated "carrier" is at 3020 kHz. I have verified that it's originating inside the house, but I haven't yet been able to pinpoint the exact source - because it seems to radiate over the electrical wiring. It's definitely not the local oscillator of any of the four different radios that pick it up.
::
::I'm going to have to shut down all my electrical branch circuits, and bring them up one at a time to find the source - but not today.
::
::So maybe I was a little hasty in suspecting the CIA...unless, of course, they have bugged my house! Hmmm.
::Doug
:
:Hey Doug:
What's new with your carriers? Are you still around or did the CIA abduct you to Gitmo? Talk to us, we're concerned.

Lewis L.