{"id":63114,"date":"2025-06-08T07:33:34","date_gmt":"2025-06-08T11:33:34","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=63114"},"modified":"2025-06-08T07:33:34","modified_gmt":"2025-06-08T11:33:34","slug":"bobs-radio-corner-tuning-single-letter-cluster-beacons","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2025\/06\/bobs-radio-corner-tuning-single-letter-cluster-beacons\/","title":{"rendered":"Bob’s Radio Corner: Tuning Single-Letter Cluster Beacons"},"content":{"rendered":"
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Source: Better Shortwave Reception, William I. Orr, W6SAI, Radio Publications Inc., Wilton, CT, 1st Edition, p. 25, 1957.<\/p><\/div>\n

Tuning Single-Letter Cluster Beacons<\/h1>\n

by Bob Colegrove<\/strong><\/p>\n

Part of the allure of shortwave listening for me has always been vicarious visits to \u201cthose faraway places with the strange-soundin’ names.\u201d\u00a0 After one has logged several big-time broadcasters, one begins to look for new challenges.\u00a0 Most of the so-called \u201cutility\u201d content which once occupied the space between the broadcasters and hams is now a vast open desert interrupted only with an occasional digital buzzsaw, a wide-band CODAR experiment, or some RTTY.\u00a0 But now and then you come across a signal that grabs your interest.\u00a0 In this case it happens to be a group of signals referred to as the Russian single-letter beacons.\u00a0 A good introduction to these beacons is here<\/p>\n

https:\/\/en.wikipedia.org\/wiki\/Letter_beacon<\/a><\/strong><\/p>\n

and here<\/p>\n

https:\/\/www.hfunderground.com\/wiki\/Letter_beacon<\/a>.<\/strong><\/p>\n

After many years, there is still some speculation as to the history, purpose and power of the single-letter beacons.\u00a0 Rather than repeat what has already been said, this posting focuses on my technique for monitoring a subset of these beacons called \u201ccluster beacons.\u201d\u00a0 They are called that because they are grouped close together, just 100 Hz apart, at ten different locations across the shortwave spectrum.\u00a0 A good tabular summary is at https:\/\/priyom.org\/military-stations\/russia\/single-letter-beacons<\/a>.\u00a0 Some stations may not currently be broadcasting or may be on at selected times.<\/p>\n

These stations will neither captivate you with content or readily QSL.\u00a0 They are all continuous wave (CW) and are thus heard by turning on your radio\u2019s beat frequency oscillator (BFO) or selectable sideband (SSB) detector.\u00a0 I am Morse-code-challenged \u2013 always have been.\u00a0 Fortunately, these stations all broadcast their single letter dits and dahs repeatedly and slowly.\u00a0 Having relatively low power, the challenge here on the East Coast of North America is just to pick them up through the band noise.\u00a0 Some nights are better, some not so good.<\/p>\n

For purposes of this posting, I have focused on the stations around 7508 kHz.\u00a0 This seems to be the best cluster, at least at the current time and location.\u00a0 \u201cD\u201d is invariably the strongest and most consistent, with \u201cP,\u201d \u201cS,\u201d \u201cC,\u201d and \u201cA\u201d fading in and out at different times depending on the propagation.<\/p>\n

To tune through the cluster, first tighten up your selectivity as narrow as possible \u2013 500 Hz if you have it.\u00a0 Use the fine-tuning control \u2013 10 Hz if you have it.\u00a0 The best way to catch these beacons is to sneak up on them.<\/p>\n