The D marker: one Morse letter repeated for years on 5292 kHz

What you hear

A single Morse letter, D, sent over and over: a dash and two dots, a pause, a dash and two dots. The rhythm never changes, the pitch never changes, and it has been doing this for years on 5292 kHz. Among the Russian channel markers, which announce themselves with buzzes, pips and squeaks, this one is the plain-spoken relative: no sound effects, just one letter repeated into the night.

That makes it useful in a way the others are not. If you have never heard Morse code on a real signal, this is the place to start: one letter, slow enough to follow, clean enough to recognise, and always there. It is also a convenient test signal. Point a CW decoder at it and it should print a steady column of the letter D; if it prints anything else, the decoder's settings, the filter or the receiver's tuning need adjusting, and you can fix them on a signal that never does anything unexpected.

Who transmits and why

The D marker is a channel marker of a Russian military net, in the same role as the Buzzer on 4625 kHz, only in Morse instead of sound. A single repeated letter is a classic way to hold a frequency: it identifies the channel to anyone who knows the letter, it shows that the transmitter is on, and it stops with the first keystroke of real traffic. The T marker on 4325 kHz, a single dash repeated in the same way, belongs to the same net and has its own page in this guide.

Beyond that, little is known for certain. The catalogue does not give a transmitter location, the net has never been identified officially, and whether any traffic ever interrupts the letter is something a listener has to find out by listening. Everything the station sends is in the clear, and listening is receiving, nothing more.

When and where to listen

5292 kHz is in the 60 metre range and behaves accordingly: in daylight it covers a few hundred kilometres around the transmitter, after dark it reaches across Europe. A Morse signal is narrow and punches through noise far better than voice, so the D marker is often readable on receivers where the voice channels of the same net are not. Receivers in eastern Europe, the Baltic states and Finland tend to hear it best; from western Europe it is an evening and night signal.

The program tunes it in CW with a narrow passband, which is the right choice: the letter comes out as a clean tone in the middle of the audio, and the filter keeps neighbouring utility signals out. If the tone is uncomfortably high or low, a retune of a few tens of hertz changes the pitch without losing the signal.

In ShackDeck

Station catalogue → Mystery stations → D Marker 5292 kHz. The program picks a public receiver that covers 5292 kHz, tunes it and sets CW with a narrow filter, so no receiver, antenna or account of your own is needed. Switch on the CW decoder and the program prints the letter as it is sent, a line of D's growing on the screen, which is a quick way to confirm that the decoder is working before you try it on a real contact.