Peter King - M0LNB
Playing with Radio, Satellites and the Moon
HF Communications
This page shows what I'm doing in HF as I learn, set things up and understand how it works. It is based on experiences with my HF station at M0LNB. Please note I'm always eager to learn more and there could be something incorrect here, but will try to make it as informative as possible.
HF: SWL
HF: Propagation
HF: Link Budget
HF: Loop Antennas
HF: Rybakov Vertical Antenna
HF: Beamforming and Interference Cancellation
HF: Loop Rotator
HF: Antenna Matching/Tuning Unit (ATU)
HF: Radio - ic7300
HF: Software - WSJT-x
HF: Software - FT8 Modulation and Coding
HF: CW Morse
HF: CW AudioBooks
HF: SWL
The following table shows stations I have copied or listen to from my QTH in London, UK.
There are many Chinese stations not listed here because I don't listen to them.
I can recommend WRTH Web App for complete local and global listings of LW, MW and SW radio broadcasting stations (and TV).
| Start kHz | Stop kHz | Type | Details |
|---|---|---|---|
| 3kHz | 30kHz | VLF - Very Low Frequency | |
| 30kHz | 300kHz | LF - Low Frequency | |
| 300kHz | 3000kHz | MF - Medium Frequency | |
| 3000kHz | 30000kHz | HF - High Frequency | |
| 30kHz | 300kHz | LW - Long Wave Broadcast | 198 BBC R4 |
| 300kHz | 530kHz | ||
| 530kHz | 1700kHz | MW - Medium Wave Broadcast | 648 R. Caroline |
| 1700kHz | 1800kHz | ||
| 1800kHz | 2000kHz | 160m Amateur Radio | |
| 2000kHz | 2300kHz | ||
| 2300kHz | 2495kHz | 120m Shortwave Broadcast | |
| 2495kHz | 3200kHz | ||
| 3200kHz | 3400kHz | 90m Shortwave Broadcast | |
| 3400kHz | 3500kHz | 3413 Shannon Volmet | |
| 3500kHz | 4000kHz | 80m Amateur Radio | |
| 3900kHz | 4000kHz | 75m Shortwave Broadcast | 3955 Ch292, 3975 R. Gold |
| 4000kHz | 4750kHz | ||
| 4750kHz | 5060kHz | 60m Shortwave Broadcast | |
| 5060kHz | 5100kHz | ||
| 5100kHz | 5400kHz | 60m Amateur Radio | Parts of |
| 5400kHz | 5730kHz | 5450 RAF Volmet, 5505 Shannon Volmet, 5550 Oceanic ATC | |
| 5730kHz | 6295kHz | 49m Shortwave Broadcast | 5940.55 R. Europa, 5960 V. of Turkey, 6030 Romania Intl 6035 BBC WS, 6040 R. Delta, 6070 Ch292 6130 R. Netherlands, 6140 R. Onda, 6150 Europa 24 6160 R. Gold |
| 6295kHz | 6890kHz | ||
| 6890kHz | 6990kHz | 43m Shortwave Broadcast | |
| 7000kHz | 7300kHz | 40m Amateur Radio | |
| 7100kHz | 7600kHz | 41m Shortwave Broadcast | 7205 R. Romania, 7455 TRT Erdogan |
| 7600kHz | 9250kHz | 8957 Shannon Volmet | |
| 9250kHz | 9990kHz | 31m Shortwave Broadcast | 9330 WBCQ, 9500 TWR Afrika, 9690 R. Espana |
| 9990kHz | 10100kHz | ||
| 10100kHz | 10150kHz | 30m Amateur Radio | |
| 10150kHz | 11500kHz | ||
| 11500kHz | 12160kHz | 25m Shortwave Broadcast | 11710 V. of Turkey |
| 12160kHz | 13570kHz | 13264 Shannon Volmet | |
| 13570kHz | 13870kHz | 22m Shortwave Broadcast | 13670 WCR, 13755 R. New Zealand Intl, 13790 BBC Fr |
| 13870kHz | 14000kHz | ||
| 14000kHz | 14350kHz | 20m Amateur Radio | |
| 14350kHz | 15030kHz | ||
| 15030kHz | 15800kHz | 19m Shortwave Broadcast | 15290 NHK World R. Japan, 15300 R. France Intl 15350 V. of Turkey, 15455 R. France Intl |
| 15800kHz | 17480kHz | ||
| 17480kHz | 17900kHz | 17m Shortwave Broadcast | 17600 Ifrikya FM, 17700 BBC |
| 17900kHz | 18068kHz | ||
| 18068kHz | 18168kHz | 17m Amateur Radio | |
| 18168kHz | 18900kHz | ||
| 18900kHz | 19020kHz | 16m Shortwave Broadcast | |
| 19020kHz | 21000kHz | ||
| 21000kHz | 21450kHz | 15m Amateur Radio | |
| 21450kHz | 21750kHz | 13m Shortwave Broadcast | 21580 R. France Intl |
| 21750kHz | 24890kHz | ||
| 24890kHz | 24990kHz | 12m Amateur Radio | |
| 24990kHz | 25670kHz | ||
| 25670kHz | 26100kHz | 11m Shortwave Broadcast | |
| 26100kHz | 28000kHz | ||
| 28000kHz | 29700kHz | 10m Amateur Radio |
HF: Propagation
This tool, HF Prop Calc by M0LNB, provides a fast, closed-form estimate of median radio-wave propagation loss and usable frequency ranges between two locations, using a simplified engineering model inspired by ITU-R P.533 ionospheric propagation principles.
For HF paths (≈1.8–30 MHz), the model estimates great-circle distance, F-layer critical frequency, oblique MUF, LUF, D-layer absorption, and multi-hop effects using monthly median solar conditions (via F10.7 solar flux) and local time. Results represent long-term median behaviour under quiet geomagnetic conditions and are intended for engineering insight, comparison, and planning rather than real-time prediction.
For MF and upper-LF frequencies (≈0.1–1.8 MHz), the tool applies a hybrid propagation model that includes conductivity-dependent surface-wave ground loss for short to medium paths, and skywave propagation for longer distances where ionospheric reflection becomes dominant.
The model does not perform ray-tracing and does not include antennas, terrain diffraction, sporadic-E, auroral propagation, short-term ionospheric variability, or space-weather disturbances. Accuracy is typically within several dB of professional planning tools for mid-latitude HF paths when used within its intended domain.
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HF: Link Budget & SNR Calculator
This tool, HF Link Calc by M0LNB, estimates received signal strength and overall link quality using transmitter power, antenna gains, receiver characteristics, operating bandwidth, and environmental noise. It is designed to work in conjunction with the site’s HF propagation calculator, which provides the Total Loss value based on ionospheric and path modeling.
By combining propagation loss with station parameters, the calculator determines received power at the antenna connector, noise and interference levels, and the resulting SNR, SIR, and SNIR. This enables realistic evaluation of HF communication performance under different operating conditions and RF environments, from quiet rural locations to dense urban interference.
This tool is useful for:
- Comparing transmitter power levels and antenna configurations
- Evaluating receiver noise figure and bandwidth selections
- Understanding the impact of natural noise and man-made interference
- Estimating link margins for AM broadcast, SSB voice, CW, data, and weak-signal HF modes
All results are theoretical and intended for planning and comparison purposes. When accurate propagation loss inputs are used, the calculations closely reflect real-world HF system behavior.
| Parameter | Value |
|---|---|
| Total Loss (dB) | 0 |
| TX Power (dBm) | |
| TX Antenna Gain (dBi) | |
| RX Antenna Gain (dBi) | |
| RX Power at Antenna Conn (dBm) | 0 |
| RX Power at Antenna Conn (dBm/Hz) | 0 |
| Radio NF (dB) |
|
Bandwidth |
| Natural Noise Floor (dBm/Hz) | |
| SNR (dB) | 0 |
| Interference Environment | |
| Interference Floor (dBm/Hz) | |
| SIR (dB) | 0 |
| SNIR (dB) | 0 |
The natural noise comes from Atmospheric (storms), Galactic (Milky Way thermal radiation), Solar (Sun emissions) and Thermal (kTB). Atmospheric usually dominates.
The interference, or man-made noise comes from Power distribution systems, Switch-mode PSU, Consumer electronics, industrial and commercial equipment, Transportation, Lighting and Telecommunications.
HF: Loop Antennas
I use two loop antennas, both on rotators and combined in an antenna phasing summing unit for receive; this enables nulling and cancellation of interference and some array gain (up to 3dB). The actual loops are 1.2m in diameter and use two parallel coils to lower the inductance. The material used is underfloor heating pipe about 1" diameter. The amplifiers are from LZ1AQ and work very well. There is an outdoor unit (differential high IP3 amplifier) and an indoor unit (bias and balun) connected together with screened CAT6A Ethernet cable. Here are some photos of what I constructed.
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HF: Rybakov Vertical Antenna
On HF my main interest is listening and DX, but when transmitting it is usually FT8, and for this the Rybakov vertical antenna is adequate for me and the size of our garden here. The performance is quite good and it is wideband from 40m to 10m bands. When combined with a tuner, it works fine for FT8. Note I only use the Rybakov for TX and loops for receive. Another plus is it's very cheap to build (<£100) and you can make it in a few hours. The VSWR plot below is measured in the shack and includes the 4:1 unun and 20m of Hyperflex 13 cable but excludes the ATU matching unit.
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HF: Beamforming and Interference Cancellation
HF: Loop Rotator
HF: Antenna Matching/Tuning Unit (ATU)
HF: Radio - ic7300
HF: Software - WSJT-x
HF: Software - FT8 Modulation and Coding
HF: CW Morse
I'm learning morse code
First thing I did was learn the sounds of the characters with these hilarious videos:
| Letters |
Numbers & Punctuation |
Then I started using the following training websites:
G4FON Koch CW TrainerCW Player
Learn CW Online
CW Academy Morse Code Trainer
Morse Walker
Morse Invaders
G4FON is my favourite for copying and F6DQM for sending. Learning by myself, at my own speed, and practise around 30 minutes a day.
The files included with G4FON are very good. Here are some additional files I made you can play in G4FON:
Short QSO made in Py by M0LNB
Ragchew QSO made in Py by M0LNB
Here are my keys, gifted to me by my family!
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Copy progress:
As of Dec 2025, I am focusing on perfecting 20wpm / 5wpm Farnsworth, aiming for instant recognition of the character sounds. Following the Koch approach and adding characters one by one. Copying small words mainly.
Some notes about learning Morse:
Most people find copying difficult but sending easier. So start with focusing on copying. Use Koch + Farnsworth.
What “Head Copy” Really Means
Head copy means you’re hearing Morse code and **understanding the meaning directly**, instead of translating each dit/dah to a letter on paper. It’s the way fluent operators “hear” words — like a spoken language.
Just Starting
At the very beginning, your brain is still associating sounds with letters. * It’s okay to **write down** the characters for a while. * Focus on **instant recognition of sounds** (not counting dits and dahs). * Don’t worry about words yet — focus on letters and simple short words.
The Smart Way to Start Building Head Copy Early
1. **Use the Koch or Farnsworth method**
* Start with 2 characters (e.g., K, M), add one at a time. * Play them at **full speed (15–25 WPM)** but with **longer spaces** (5-12 WPM) between letters. * This trains your ear to recognize the *sound* of each character.
2. **Say the letters in your head instead of writing them down**
* Example: hear “K” → mentally say “K” → move on.
3. **As you get comfortable, move to short words**
* “THE,” “AND,” “YOU,” etc. * Try to hear them as a *unit sound* rather than individual letters.
4. **Later — sentences and comprehension**
* Gradually transition to hearing meaning, not letters.If you always write every letter, your progress toward head copy will slow down. If you *only* do head copy too early, you may get frustrated. The best balance: **alternate both methods** — write some, think some.
**30-Minute Daily Head-Copy Plan**
**1️⃣ Character Recognition (10 minutes)**
**Goal:** Train your ear to *hear* each character instantly. * Start with **2–3 characters** (e.g., K, M, R). * **Speed:** 20 WPM character speed, 10 WPM effective (Koch + Farnsworth style). * **Method:** * Listen to random characters. * Don’t write. Just **say the letter in your head** as soon as you recognize it. 🧠 *Tip:* You’re training your brain to hear whole sound patterns, not dits and dahs.
**2️⃣ Short Word Copy (10 minutes)**
When you have mastered >6 characters, introduce words. Increase characters to >6 and reduce effective speed to maintain accuracy. **Goal:** Start recognizing *sound patterns of whole words.* * Try to **understand** them in your head without writing. 💡 *Hearing “THE” as one sound instead of “T-H-E” is the foundation of head copy.*
**3️⃣ Short Sentence Copy (10 minutes)**
When you have mastered >10 characters, introduce short sentences. **Goal:** Train comprehension directly in your mind. * Listen to a short sentence (5–7 words). Example: > “THE CAT IS ON THE MAT.” * Don’t write. Just **visualize** or **say the words silently** as you hear them. * Repeat once or twice. * If that’s too fast, go back to shorter word groups. 🧘 *Tip:* Relax. Morse comprehension is like learning to recognize spoken accents — it improves subconsciously.*
Learning to send
I use a paddle and connect it to my IC-7300, ensuring BK-IN is off and squelch is at maximum. Then I use CW Player by F6DQM. Selecting monitoring, I can practice sending and the text is written to the screen.
Example QSO with K1ABC
- QRL ?
- QRL QRL
- E E
- QRL ?
- CQ CQ CQ DE K1ABC K1ABC K
- K1ABC DE M0LNB M0LNB KN
- RR M0LNB DE K1ABC TNX FER CALL
- UR RST 599 5NN QTH QTH IS MIAMI MIAMI NAME NAME IS BRAD BRAD
- SO HW CPY? M0LNB DE K1ABC KN
- RR K1ABC DE M0LNB UR RST 559 55N
- QTH IS LONDON LONDON NAME IS PETER PETER
- SO HW CPY? K1ABC DE M0LNB KN
- RR M0LNB DE K1ABC BT
- WX HR SUNNY TEMP IS 80F 80F MY RIG IS FTDX10 FTDX10
- ANT IS DIPOLE UP 30 FT SO HOW COPY? M0LNB DE K1ABC KN
- RR K1ABC DE M0LNB WX HR RAIN TEMP 10C 10C RIG IS IC7300 IC7300
- ANT IS VERT ES LOOP SO HW CPY? K1ABC DE M0LNB KN
- RR M0LNB DE K1ABC TU FER FB QSO HP TO CUL 73 SK M0LNB DE K1ABC KN
- RR K1ABC DE M0LNB TU FER GRT QSO HP TO CU AGN SN 73 SK K1ABC DE M0LNB SK E E
- E E
Prosigns - Procedural Signals
- BT Full Stop, end of a sentence. I'm still here thinking what to say next
- SK QSO at an end. I'm not going to send any more after this sentence
- AS Wait. Hold on I will be right back
- AR I'm done sending, now it's your turn
- BK Please clarify
HF: CW AudioBooks
Here is my collection of audiobooks read in CW.
QSO by G4FON (30wpm / 3wpm Farnsworth)
Text used as input
QSO by G4FON (30wpm / 6wpm Farnsworth)
Text used as input
Green Eggs and Ham by Dr Seuss (30wpm / 5wpm Farnsworth)
Text used as input
Always Look on the Bright Side of Life by Monty Python (30wpm / 5wpm Farnsworth)
Text used as input