Short Wave Listening at N6CC

Early Short Wave Listening, Numbers Stations, The Woodpecker etc

As with many Hams I started out young as a Short Wave Listener “SWL”. Even today, long after I earned my Ham license I still spend a lot more time listening (to everything) than I ever did talking with other Hams. I also learned a lot about “the world” in the process.

It started out with the family’s “All American Five” table radio that also had some portion of the “short wave broadcast bands” accessible via a rear-panel band switch. Not this one:

Hallicrafters S-120 Slide Rule Dial
Hallicrafters S-120 Receiver Slide Rule Dial

What’s going on here? Governments using Short Wave radio broadcasting to influence international public opinion in their favor – since the 1930’s. Sounds familiar…. These days they use “social media” to program the Smart Phone Zombies.

“When you control the information you control the people.” Nazi Reichsminister of Propaganda Joseph Google (er, Goebbels).

With the rise of the Internet and “cable” most broadcasting has moved off “radio” over to various web-based services. With few exceptions there is not much international news and information on short wave radio these days. However there is still plenty of other interesting stuff on the HF radio spectrum not controlled by the corporate media.

At age 9-10, I knew that I needed to set up a proper “Listening Post” with the radio. That I did, in the back of a small clothes closet, complete with my microscope and chemistry set. The wall was adorned with a few SWBC QSL cards. The back yard trees were full of wires, the “basement shack” was wired with multiple knife switches to select each one.

Then came a Heathkit CR-1 Crystal Radio my dad built for me while I was in the 5th Grade. See:

That was closely followed by a sadly broken Zenith Transoceanic 8G005 portable given to me by uncle Dan to “play with”. As a curious 10 year-old, I disassembled it!!! OH THE PAIN!!! (but I still have all the Loctal tubes 60 years later.)

Then came the Hallicafters S-120 Receiver:  I received one as a gift from my parents for Christmas in 1963.  Priced at $69.95 I am sure that was the better part of my parents combined weekly pay. Thanks again Mom and Dad!

It replaced the old “AA5” table radio in my Listening Post. A life long buddy would often come over and we would both marvel at what “radio” was and what it could do.  That bug bit both of us pretty hard!

This S-120 is a recent addition – I had given away to a local kid the original S-120 which was my first “real” shortwave radio when I was a kid. The “informative” slide rule dial even told you where to tune to receive “Paris”, “China” and other exotic locales. Plus – Aviation!

Even by 1960’s standards it’s pretty (very) marginal but I didn’t know any better back then. I logged lots of DX with it and it still sounds pretty good on SWBC. I can (barely) copy CW and SSB with it, but stability is another adventure.  Medium wave AM broadcast is OK, actually pretty good.

The S-120 has only 4 tubes; no RF amplifier stage, so it was pretty deaf well into the higher short wave bands. The circuit is nearly identical to the early S-38 sets but they used Octal tubes versus the 7-pin miniatures of the S-120.  The S-120 also replaced the S-38’s rectifier tube with a selenium stack in the half-wave bridge power supply.  1940’s Tech.

The Ameco PCL-P 2-Nuvistor cascode preamp helps considerably!

The preamp adds the critical RF stage plus tuned preselection to reduce image response..

The Hallicrafters S-120 ad from 1961. Politically Incorrect these days (but still accurate) . Yes, I heard him. Comrade Castro: When the “cure” is vastly worse than the “disease”. I listened/en to it all go down, from various sources, in real time. “IT’S THE EMBARGO!” Ummm, no.

Reports included Fidel Castro and Che “Up Against the Wall!” Guevara as they then tried in vain to export “The Revolution” to southern Africa, Central and South America.  Then of course Castro’s cheerleaders like Vladimir Posner of Radio Moscow and later “Ed Newman” of Radio Havana Cuba with their sadly laughable propaganda successfully manipulating Lenin’s “Useful Fools” and those who profit from them.  But I digress.

I often listened to the BBC and VOA’s “Daybreak Africa” program and heard the strange sounding (to me) names of the various African leaders at the time.  People like Kasa-Vubu, Patrice Lamumba, Moise Tshombe, Kwame Nkrumah, Habib Bourgiba and of course Nasser etc. Those names sound somehow familiar to me even today, buried deep in my wetware..

Back in the early 1960’s Ham radio communications was still largely Amplitude Modulation – voice. I listened to Hams for hours, wondering who they were, how they were able to use a radio (like mine?) to talk to each other and what the heck they were even talking about. Ladder line, 1625’s, VFO’s, D-104’s, QSL’s, Homebrew etc. Didn’t know what it was but I wanted some! Then my uncle Paul gave me a Heathkit catalog.

One fond memory as a thirteen year-old during the S-120 days was listening to lots of interesting non-voice and “Utilities” signals that crowded the bands back then – and wondering what they were. Those included WWV time signals which ID’d in those days by Morse Code, the first Morse letters W W V I knew by sound.

I lived about a mile from Mitchel Air Force Base on Long Island in the 1950’s – 1960’s. As a young kid I could identify dozens of different USAF aircraft by sound alone as they flew nearly over our house on approach to Runway Three-Zero. So….

There was a peculiar, distinctive signal at many points on the S-120 dial. Sort of like a continuous, droning, guttural “Grrrrrrrr” sound. It sounded just like a four engined B-17 bomber in flight. (Que the sound track from “12 O’Clock High”)  I just KNEW that’s what I was listening to on the radio. I also thought it might be JAMMERS!

It wasn’t until later in life when I was in the U.S. Navy that I learned what those (and many other) signals actually were. Four-channel multiplexed radio teletype transmitters.

What I was hearing was probably the Navy’s AN/FGC-5 or AN/UGC-1 four channel HF Teletype systems in operation on the east coast and LANT Fleet Op areas.

Hmmmmm, The B-17’s had four Wright Cyclone R-1820 radial engines running asynchronously. Four independent asynchronous Baudot RATT signals. Nine cylinders per engine. At at 5 bits each character plus a start and stop pulse (7 bits total). Acoustically / spectrally speaking, a pretty close match! No wonder I was fooled! The East Coast of the U.S. had lots of that kind of military traffic going on back then…

There were the big Press Wireless and several other ship-to-shore radio stations on Long Island and the east coast to copy with my ARC-5 receiver, dynamotor humming away.

Then there are the so-called “Numbers Stations“. I copied a lot of 5 number/letter Morse Code cypher groups from them. They were excellent code practice as I studied for my various ham license tests. They are a favorite topic on the Interwebs.

Below: Putting the CIA’s RS-6 Spy Radio to work on numbers stations. Spying on spies; and keeping your coffee warm while on a late-night Op.

Mission Essential Equipment

Encrypted short wave transmission is a favorite cheap, simple and effective method known to be used by the Cuban Dirección de Inteligencia service to communicate with their spies.* (Reference 92.)

When encoded with a One Time Pad (OTP) cypher and used correctly, the contents of these “numbers” transmissions are unbreakable. This system is presumably used by many other countries and organizations.

Below are 2 recordings I made late at night of a reportedly well known Cuban transmitter, a.k.a. “M8A”. The first 2 using Morse Code cut-numbers of a non-standard (Cuban, or false-flag) variety. 1=A, 2=N, 3=D, 4=U, 5=W, 6=R, 7=I, 8=G, 9=M, 0=T (Reference 93).

The first one sounds like a call up to several “out stations”. Starting with call signs; (note the triple DDD and GGG. Statistically very highly unlikely in an encrypted message, especially in adjacent Groups.) This preceded a transmission of many cypher groups. 5800 kc around 0600Z. Copied with my CIA RS-6 radio set (above). Click the Arrow buttons:

Numbers Station callup

The above MCW (A2A) transmission continued with 5 cut-numbers cypher groups. Someone’s One Time Pad would be getting a workout. The “Cuban 5” spy ring perhaps?

An advantage of using cut-numbers is that the agent does not need to be “Morse Code qualified”. With minimal communications training they just need to know those 10 simple, 2 or 3 element letters. Those are also much faster to send than the actual 5 element numbers in the standard code. That reduces transmitter “on air” and exposure time.

A related OTP system transmits letters versus numbers. This system requires higher level Morse Code skills typical of professional communicators; all letters are utilized. As with the “cut-numbers” system the conversion of letters into different letters when mixed with the OTP key is via an UNCLAS “Trigraph” table during encryption/decryption.

Here is another station I copied on 11460 kc with a voice preamble in Spanish followed by a multi-tone alert and then digital data streams. Someone has gone “high tech” in this one. Can you say Sound Card? Easy to distribute OTP Keys on a thumb drive via a Dead Drop.

*During the prosecution of numerous Cuban spies in the U.S. the FBI was required by court proceedings to reveal seized evidence of the Cuban spies use of Short Wave radio and associated encryption systems.  Sufficient to convince a lay Jury.  Convictions followed. But I digress.  Again.

But “numbers stations” are a whole ‘nother topic…

The “Secrets” of DUGA: Another signal I couldn’t avoid hearing with my trusty S-120 and my HA-350 was the Soviet дуга Over The Horizon Radar that they had built near Chernobyl in Ukraine.

“Arc” in Russian, its signal was plenty loud in the U.S. at the time with its massive effective radiated power. Arc probably indicating its over-the-horizon mission.

This gigantic phased array antenna with its broadband cage dipoles fed by open wire transmission lines and linear wire reflector screen is 500′ tall and nearly a half-mile wide. There are actually 2 arrays here, one “small” and the other much larger. Likely for high and low frequency operation respectively. I’d have to visit.

(Can you find the man in the photo below?)

DUGA Radar antenna array. Photo credit: Peter Franc

The Ignoraty and Conspiracy Whacko’s described its purpose as mind control, weather control, Soviet HAARP, death rays, an earthquake trigger, etc. Dude! Like it totally caused Chernobyl to freakin’ EXPLODE! and THEN Explain Hurricane Katrina to me. Huh! Huh!

CNN opined in a March 4th 2019 article that it has “a far more sinister and mysterious reputation.”   CNN continues: “its true purpose and the important details of its functioning are covered in mystery.”  (Umm no CNN, it’s purpose and function was EXACTLY understood – 40 years ago.) 

That CNN Travel article included a map with the locations of the radar and the Chernobyl nuclear power plant (reversed).   “News you can trust”…

The radar sounded like a staccato pulse train of about 10 pulses per second, spread over a very large bandwidth. It jumped around in frequency as they adjusted it to deal with HF propagation realities, appearing nearly everywhere at times in the HF spectrum.

The 2 main DUGA broadside antenna arrays (NATO variously Code named Steel Yard or Steel Work/s) were built along an axis of 053/233 degrees true (See Google Earth 51 degrees 18.30N 30 degrees 4.00E).  This is reported as the receiver site, the abandoned/dismantled transmitter site is about 50 km away to the northeast on that same 053 degree axis.

The system emits and then receives the reflected return signal at right angles to the dipoles/reflector array off to the northwest on an azimuth of 233+90=323 degrees true. If you plot that azimuth from the site, it goes over eastern Europe, Scandinavia, Greenland, Hudson Bay then directly over the ICBM missile fields in north-central U.S. Check.

No “secret” or surprise there, that was the threat axis they wanted to monitor.  How about range capability?

With its 10 pulses-per second, the interpulse period is 100 milliseconds.  As every radar operator knows, radar pulses (radio/light) travel 328 yards per microsecond.  That works out to a one-way distance of about 20,000 miles before the next pulse is transmitted.  Since radar is a round-trip system, the max detection range is half that, about 10,000 miles before the next pulse is transmitted, deafening the receiver.

That range has to include extended “side” trips up to the ionosphere and back, at least twice, likely 4 times.  Also, the Transmit/Receive “T-R” switch that protects the receiver from the massive transmitted pulse needs some recovery time, as does the receiver itself. So the effective detection range to a target would be more like the 5,000 ground miles to the center of the ICBM missile fields from DUGA. Check.

There CNN, solved if for ya.  “Important Details” revealed with a 4-tube Hallicrafters S-120 receiver, Google Earth (or CORONA satellite imagery) and a simple slide rule.

They located the radar in the southwest part of the then USSR (in Ukraine) to avoid HF radio propagation disturbances over the north polar areas, think “Northern Lights” etc.

As an aside, today there are the remains of a what appears to be a big Wullenweber or related CDAA direction finding receiver antenna. The site is exactly 1 mile SW of DUGA along that 233 degree array axis, probably in a DUGA antenna system pattern null to protect it from the transmitter pulse energy.

This site is known as “KRUG” (circle in Russian) and has been reported as a possible ionospheric chirp sounder. Makes sense – queing DUGA to the optimum frequencies for operation. The word азимут (azimuth) is seen on an interior control panel. Indicating to me that this detects favorable propagation paths both in frequency and direction.

I noticed when DUGA often shifted into the internationally allocated Amateur Radio ham bands (in violation of international law which the Soviets signed: nothing to see here, move along). When it showed up, that 10 PPS signal sounded just like a woodpecker, obliterating all communications on those frequencies. Hence its colloquial name among hams and other radio communicators: the Russian Woodpecker

FUN FACT: When THAT happened I found myself needing to test my transmitter and electronic CW keyer on frequencies allocated for ham radio use. Testing my keyer at 10 dots per second, or thereabouts, on the DUGA frequency, or thereabouts, I could often get them to move off frequency. My puny 40 watt CW signal was significantly stronger than any reflection they could detect off a missile or aircraft or maybe even North Dakota ground clutter.

Doing my part in the Cold War…LOTS of other Hams tested their equipment in a similar manner. “Woodpecker Hunting”…

Must have driven their operators crazy as it was apparently fairly easily “jammed”, accidentally of course. I don’t know what kinds of pulse-forming networks* or signal processing in the receivers they used at the time but it was probably adequate given the technology available. Transversal matched-filter gymnastics notwithstanding…

My chirpy Novice transmitter pulses probably looked like up-doppler shifted INCOMING!…

* Russian engineers were/are particularly good at designing pulse forming networks and pulse power machines. Apparently not so good at operating nuclear power plants. The DUGA site was abandoned in 1989 due in part to significant radiation contamination from the melt down of Chernobyl (and the melt down of the USSR and the Communist Party).

There are some You Tube videos of this antenna array and probably thousands of online photos. Sadly, NONE of them were taken by an Electronics Engineer!

In the early 1980’s I was building equipment to work amateur radio teletype stations. I was using a Yaesu FT-101E, a DIY converter, an AEA CP-1 Computer Patch, an Early IBM PC running a DOS 2.0 terminal emulator and an Epson dot matrix printer all serviced by simple dipole antennas.

I made my first RTTY contact with Chip N7CPC near Seattle, one of the original Pacific Northwest Clatternet guys on 30DEC83.

My home made “Under Ground Communications -1” TTY Converter – now interfacing with a PRC-47/CV-2455 as a Loop-To-RS-232 converter weekly on Clattenet II.

Radio Teletype Convertor N6CC

North Korean Radioteletype! While SWL-ing, I was tuning around with my FRG-7700 and found the North Korean KCNA station in Pyongyang transmitting English language propaganda via Radio TELETYPE! Huh? They had a pretty strong signal into the west coast on 13580 kc running 60 WPM Baudot.

Maybe they were forwarding program material to Radio Havana. It often included quotes from prominent american Democrats who were also cheered from Havana.

The teletype broadcasts were pure Communist fantasy land extolling the Godlike Personality and Immortal Feats of Great Leader Kim Il Sung as he battled Koreans and reality.

A common theme was re-retelling of the “courageous capture of the Imperialist running dog capitalist’s heavily armed warship USS Pueblo by the Glorious Peoples Navy” [sic] over (then) 15 years ago, etc. Yada yada. Another common theme was sending “Congratulatory Greetings” to other Marxist-Stalinist hell holes upon the “reelection” of THEIR Glorious Leaders.

In addition to the S-120, I’ve had many different receivers over the years.. These include several cheap AM/FM/LW/SW portables, S-38, IC-SW7600, FRG-7700, BC-348R, Command Set receivers, TCS sets and a couple of hand-cranked AM/FM/SW “emergency” radios.

As a life long CW operator I also have an R-390A, the King of them all. Its performance and sound is much preferable to me over any “modern” KenYaeIc gear. Those receivers using Digital Signal Processing become quite fatiguing to listen to rather quickly. No thanks.

R-390A Receiver


When I was in Saudi Arabia we had rental cars that all had dash-mounted (Blaupunkt?) AM/FM entertainment radios that included SW broadcast bands as standard equipment. How cool!

We heard the BBC etc. plus many Arabic/Farsi language stations being jammed by the 7th Century Iranian Mullahs, even in the medium wave AM Broadcast bands. Iran used the Soviet-style Stepped Tones jamming signal. Much to be learned from all this.

In the pursuit of this “hobby” I learned a whole lot of electronics but also the importance of “all source” information monitoring.

Keep your antennas UP!

Under Construction – More to Follow.