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One day not long ago I began noticing that if I de-tune an AM radio to the upper carrier edge of my 1550 kHz transmission I distinctly hear a “tick-a-tick-a-tick-a-tick-a-tick-a-tick-a-tick-a-tick-a-tick-a” that just goes on and on without variation.
There is no hint of this ticking sound on the center-tuned main-carrier nor on the lower sideband.
The transmitter is an AMT3000 from sstran(dot)com modified to work with a hand-wound loading-coil and Wintenna (metal window in-line with half-indoor half-outdoor vertical antenna ground clamped to basement I-beam below the floor.
Turning the transmitter audio control to zero the ticking sound stops, therefore suggesting that the sound is introduced from the 25-foot audio cable which runs from a computer audio output to the transmitter audio input.
Sending silence from Winamp over the 25-foot audio line results in the same ticking sound.
By software-disconnecting the audio feed from the 25-foot audio line does not change the ticking sound.
Viewing the silent carrier on the spectrum analyzer shows no artifact produced by the ticking sound.
The ticking sound is not interfering with another station because it is not far enough out on the side-band to reach another channel, it’s in the “splash-zone” of the main carrier.
The ticking sound is not causing an actual problem… it’s just “there”, but naturally I’d like to discover what’s causing it to happen.
I’ll be examining it from time to time, but also seek your input about what might be taking place. If it happens to me it could happen to others, so we need to establish a “cause-solution” file.
Total posts : 45366
Total posts : 45366That Cuban station (Radio Reloj) came in here one night on 570 KHz while I was looking for a carrier current frequency.
The ticking thing on my 1550 kHz upper sideband is nothing like the Radio Reloj clock, there’s no voice, no morse code, and it goes away when I turn off either the transmitter or the audio input to the transmitter.
One amazing fact is that time itself advances at the same rate without ever listening to a time radio station!
Total posts : 45366Maybe you have a ticking time bomb there.
Seriously, the ticking sounds like it’s the transmitter causing it….maybe something inherent to this transmitter.
Also could be your audio source since it stops when you don’t have audio….what is it?…..something in the circuitry in the audio chain.
Is it worth the trouble to find it?….no, unless you want more stress in your life.
Mark
Total posts : 45366Try a different power supply for the audio chain and the transmitter.
Mark
Total posts : 45366Thank you Mark and Druid Hills for some ideas to think about.
As a part 15 life-style I actually welcome the stress brought by a whole new mysterious problem that doesn’t yet have a name.
Everything needs to be looked into, and every idea that gets posted will be tested as we look for an explanation for this ticker.
If it’s a time bomb I should probably update my will.
Total posts : 453661550 The Tick! 1550 Da Bomb, 1550 WTNT…
Total posts : 45366Is there a refrigerator/cable TV interface/cable TV box et al on the other side of the wall where your station is?
Total posts : 45366Almost reminds me of the sound wifi or cellular data makes.
Total posts : 45366My AMT3000 does the same thing no matter what radio i use to tune it in.
Keep in mind, mine is on 1620 but i have heard the same thing on other frequencies i have tune the transmitter to.May have something to do with chip that controls frequencies, this is a very broadbanded transmitter. It will tune down to longwave with some mods and up to 120 meters without mods.
Total posts : 45366No shovel required.
This is a pdf showing information on 74HC4060 14 stage ripple binary counter 16 pin which contains an oscillator. It is also used for the following applications.
Control countersTimersFrequency dividersTime-delay circuits
Total posts : 45366You know, I was wondering myself if it wasn’t something to do with the PLL’s clock. I never noticed this with my own AMT3000 when I had it.
Total posts : 45366The ticking sound seems to be there when no modulation is present and the receiver is in close proximity of the transmitter. I just tried this out with the radio on the other side of the room and no audio, same result but the ticking was quieter.
On the other end of the house it is not heard at all.
Carl, have you noticed that as well?
Total posts : 45366Barry, of course the now famous Blue Bucket exists as an enclosure for your AMT3000 loading coil, so we have that in common… we are both running in modified mode and bypassing the small inductors used in the output filter of the normal version of the transmitter.
But you’ll note some differences in the following observations made only minutes ago.
At 2:20 PM CDT this afternoon KDX shut down completely and disconnected computer and transmitters from all outdoor connections because of a large electric wind storm.
At 3:15 PM things became calm and I decided to do some AMT3000 tests before bringing the entire system back on line.
The carrier was returned to the air at 1550 kHz with the 25-foot audio line unplugged from the transmitter and the audio input level on the transmitter turned up to the normal level. There was no ticking at all.
I reconnected the 25-foot audio line to the transmitter and turned the audio level up… the ticking returned. WHAT IS DIFFERENT FROM EARLIER TESTS IS THAT THE COMPUTER, ROUTER AND CABLE MODEM WERE STILL TURNED OFF FOR THIS TEST.
I unplugged the 25-foot audio line from the front of the computer and the ticking stopped. COMPUTER STILL TURNED OFF.
Returning the audio line at both ends I followed the ticking on a portable radio for 35-feet out to the back room of the building… the ticking was present as long as the carrier was on, although I had to be very patient because static from lightning was very constant on the AM band.
Now I’m completely back in service and the storm has moved east.
My results are not exactly the same as yours, Barry.
Total posts : 45366Well then, i would have to say the ticking is just a byproduct of the clock in the PLL and since it doesn’t affect the transmitted audio, it is of no consequence to us.
Still, to hear it does make you wonder, what if the pll (not the one in your transmitter lol) but if we had another pll if it could make a clock circuit that if the output was added to an amplifier and speaker, could it play that tick tick sound over the speaker, could add a digital clock LCD display to it and have a nifty little clock that ticks ticks every second of the day…. oh wait on second thought.
lol Too much like Chinese water torture.
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