Let's assess the situation here.
Transmitter creates a tick when turned on, to nearby receiver, only when audio cable is hooked up to transmitter and computer.
Question for you Carl, is your computer still hooked up to the mains supply, but powered off via the shut down feature of OS or powered off via the PSU switch?
Awaiting your answer before I go any futher.
Bruce.
During the test with the computer turned off but the AMT3000 on and audio cable connected at bothends...
The computor was connected to the AC power line, and turned off with the Windows shutdown method.
The AC power was switched off to the cable modem and router.
The cable was physically disconnected from the cable modem so it couldn't introduce an electric surge from a lightning strike.
Try unplugging the computer from the AC mains completely and do another test with the audio cable still plugged into the sound card. Power on the transmitter again and look for the clicking or ticking sound on the radio receiver. You are getting a possible by-product of that and another frequency, combining together, to produce the noise you hear.
This is called conducting a process of elimination.
If the noise goes away, you are picking up a possible utility power transformer pulse through the power cable and PSU of the computer system.
When you power off a computer, either by shutting down via OS shut down method or switching the PSU off by the PSU power switch, you are still connected to the mains supplying your home with electricity. The PSU switch only isolates one side of the AC supply voltage from the mains to your computer system.
If this test does not stop the noise, then I'll go to the next suggestion. One thing at at time.
Bruce.
MrBruce your process of elimination worked.
I closed down the radio station at 8 PM CDT, powered off the computer, disconnected the AC power cord from the computer, and the ticking could still be heard clearly on the upper sideband at 1550 kHz.
I decided to start disconnecting peripherals from AC, starting with the Magic Jack telephone device, the ticking continued.
Next I disconnected the power walwart for the Epson Scanner, and THE TICKING STOPPED!
To finally re-prove that the ticking was a by-product with the AM carrier, I shutdown the AMT3000 and both the carrier and the ticking went off the air.
The remaining question I have is whether the ticking component from the Epson walwart is traveling on the audio cable or whether it's radiating independently into the air.
Maybe it's not actually the walwart but the scanner itself causing the ticking.
The next test I just thought of doing is disconnecting the USB cable from the scanner to see if that stops the ticking. I'll do that next time I shut down.
Could be RFI from the scanner.
The spectrum analyzer is only 8-feet from where the scanner is located but sees no trace of the ticking on the upper sideband of 1550 kHz caused by the scanner or its power supply.
Moving around with a portable radio, the ticking is not any stronger near the computer/scanner than it is anywhere in the carrier field of the AMT3000 transmitter.
Other than existing, the ticking is not causing any problem that I can identify... it is not interfering with any other AM channel, is not audible on the main carrier of the AMT3000, and so is a benign artifact.
I guess I'll stop doing anything about it, although it is unusual in the way its appearing only on the upper sideband.
I wonder if it would be there if I changed frequency on the AM transmitter?
THAT...is bizzare
I get a ticking sound if I'm too close to my Whole House 3.0 like maybe 7 feet. But if I move further or have the receiver plugged into a different outlet that is not part of the same circuit it does not appear.
Now on my Sainsonic AX-05B (When I use to operate it before I realized it was faulty) I heard a ticking sound in between songs that could clearly be heard 30-50 feet away. Sometimes those switching power supplies are a real issue. Hopefully this does not get worse for you where it can be heard durring normal receiving of your AM station.
Up to this point all my tests were made on the main floor here in the Internet Building, where the ticking can be heard on the upper sideband of a portable radio on 1550 kHz.
Responding to a slow but eventual brain I came up with two new ideas.
#1 Try it outdoors. So I went out the door and there is no ticking out there even though 1550 comes in strong;
#2 Try the basement. So I went down and the 1550 is real strong down there because of being grounded to the I-beam total house ground, and guess what? No ticking.
The cross-relationship between the ticking and the transmitter carrier is more mysterious than a woman. I am under-qualified for this.