Digital Mode · Beginner · about 8 minutes of reading
In the previous article I explained what FreeDV is and why it is worth a try. This time it is pure bench work: FreeDV is installed, the Icom IC-7300 MK2 is plugged into the laptop with a single USB-C cable, and now every box in the software has to be filled in correctly. Here is exactly what I set, in the order I set it, including the traps I stepped into along the way.
Fig. 1 — The finished setup at YB1CPT: FreeDV 2.4.1 in RADE V1 mode on the laptop, and the IC-7300 MK2 following along on 14.236 MHz in USB-D.
What I used
Icom IC-7300 MK2, connected to the laptop by one USB-C data cable (audio and CAT control travel over the same cable)
OptiBeam antenna, radio running barefoot at moderate power
Before you open FreeDV
Four small jobs in Windows save a lot of head-scratching later.
1 · Install the Icom USB driver first
The MK2 uses Icom's "USB Driver" package (the one listed for IC-705 / IC-7760 / IC-7300MK2), not the Silicon Labs CP210x driver of the older IC-7300. Install it before plugging in the cable. It adds two virtual COM ports and the radio's sound device.
2 · Find out which sound device is the radio
Windows gives USB sound devices generic names such as "USB Audio CODEC" or "USB Audio Device", so it is easy to pick the wrong one. The quick test: unplug the USB cable, look at the list of sound devices, plug it back in. The entry that reappears is your radio.
3 · Tidy up the radio's sound device in Windows
Control Panel → Sound → find the radio device on both the Playback and Recording tabs
Properties → Advanced: 16 bit, 48000 Hz
Switch off every "audio enhancement"
Do not make it the default device, or Windows will happily transmit its notification sounds
4 · Note the COM port
Device Manager → Ports (COM & LPT). The MK2 shows two ports. Write down the number of "IC-7300MK2 Serial Port A (CI-V)"; that is the one FreeDV will use. Port B stays free for a logging program (mine runs N3FJP ACLog on it).
On the radio
Setting
Value
Why
Mode
USB-D (press USB, then DATA)
In DATA mode the MK2 takes its modulation from the USB port by default (MENU → SET → Connectors → MOD Input → DATA MOD = USB), so the microphone stays out of the signal
USB AF/IF Output
Output Select: AF, AF Output Level about 50%
Gives FreeDV a healthy receive level
USB MOD Level
Start at 50%
Fine-tuned later against the ALC meter
Filter
FIL1, width 3.0 kHz
The factory DATA-mode filters are narrow. RADE needs about 1.5 kHz of clean audio, so a narrow filter means no sync at all
COMP, NB, NR
All OFF
A digital signal wants clean, unprocessed audio in both directions
FreeDV Easy Setup, box by box
Open Tools → Easy Setup. The dialog has three steps.
Fig. 2 — My first attempt, and a classic mistake: the laptop's own Realtek sound card is selected as the "Radio Device". With this setting FreeDV listens to the laptop instead of the radio.
Step 1 · Select Sound Device
FreeDV works with two audio paths. One path connects the laptop to the radio (the digital signal). The other connects the laptop to you (your ears and your microphone). Keep them apart and everything falls into place.
Box
Fill in
Radio Device
The radio's USB sound device (the one you identified by unplugging the cable)
Decoded audio plays back through
Your headphones, or the laptop speakers (Realtek)
Transmitted audio records through
Your headset microphone, or the laptop microphone (Realtek)
A headset is the better choice. With open speakers, the decoded audio can leak back into the laptop microphone while you transmit.
Step 2 · Setup Radio Control
Choose Hamlib CAT Control and click Advanced
Rig model: Icom IC-7300MK2. Do not pick the plain "Icom IC-7300". That model talks to CI-V address 94h, while the MK2 listens on B6h, so the radio silently ignores every command. The MK2 entry arrived with Hamlib 4.7, so use a recent FreeDV
Serial port: the COM number of Serial Port A (CI-V)
Baud rate: 115200. Over USB the MK2 accepts any rate, so this value is not critical
PTT: via CAT
Press Test with the power turned down or into a dummy load. The radio should key briefly. Note that a COM port can only be opened by one program at a time, so close WSJT-X (or anything else using Port A) before starting FreeDV.
Step 3 · Setup Reporting
Tick Enable Reporting
Enter your callsign and your Maidenhead grid locator
With reporting on, your station appears on the FreeDV Reporter map, and you can see who hears you even before anyone answers.
First run
Select mode RADE V1 (the default in current versions) and press Start
Type a frequency such as 14.236 into FreeDV's Radio Freq. box. If CAT is working, the radio jumps to it straight away, and FreeDV's log shows lines like Request frequency change to 14236000 Hz
Watch the waterfall: band noise should fill it. When a FreeDV station is on frequency, the Sync indicator turns green and you hear clean voice in your headphones
Do not be surprised if the band is quiet on your first evening. Mine was. The FreeDV community is still small, especially in this part of the world, so a quiet frequency usually means nobody is there yet, not that something is wrong.
Setting the transmit level
Key FreeDV and watch the radio's ALC meter. Raise the USB MOD Level until the ALC just starts to move, then back off a little. A FreeDV signal is dense and continuous, much like a data mode, so an over-driven signal gets wide quickly and becomes harder for the other station to decode.
FreeDV transmits at close to 100% duty cycle, not in the choppy bursts of SSB voice. Moderate power is plenty, and the radio will thank you for it.
Fig. 3 — After switching the radio to FIL1 (3.0 kHz): USB-D, 14.236 MHz, ready to call CQ.
Calling CQ with the voice keyer
On a quiet frequency, let FreeDV call for you. Right-click Start Voice Keyer and choose to record a new message. It records from the device in "Transmitted audio records through". This is the script I use:
"CQ CQ CQ FreeDV, this is Yankee Bravo One Charlie Papa Tango, YB1CPT, Yankee Bravo One Charlie Papa Tango, calling CQ on FreeDV RADE from Bekasi, Indonesia, grid Oscar India Three Three. YB1CPT, calling and listening."
For weak or fading conditions, a short version works better:
"CQ FreeDV, CQ FreeDV, Yankee Bravo One Charlie Papa Tango, YB1CPT, listening."
Leave about one second of silence at the start of the recording. RADE needs a moment to sync, otherwise the first word gets clipped at the receiving end
Speak at a normal pace, 5 to 10 cm from the microphone
In the voice keyer options, set 5–6 repeats with a 10–15 second listening gap between them
Keep the FreeDV Reporter page open while the keyer runs. Any station that decodes you appears there with your SNR
Stay at the station while the keyer is running
What hands-on practice taught me
Doing the setup for real, at my own operating desk, refined the checklist from part one. The previous article has now been updated with these points:
No separate rigctld is needed. FreeDV has Hamlib built in, so select the IC-7300MK2 model directly in Easy Setup. Hamlib model 3073 is the older IC-7300 at address 94h and will not reach an MK2 at its default B6h
Operating in USB-D lets the MK2's default DATA MOD = USB do the job, and keeps the microphone out of the transmitted signal
The MK2 has no "CI-V USB Baud Rate" menu item. The USB link works at whatever rate the software asks for
When it misbehaves
Symptom
Most likely cause
Waterfall shows nothing, or only laptop noise
The Radio Device is set to the laptop's sound card instead of the radio's USB device
Test does not key the radio
Wrong rig model (IC-7300 instead of IC-7300MK2), wrong COM port, or another program holding Port A
Signals visible but never any Sync
Filter too narrow (use a 3.0 kHz filter), mode mismatch with the other station, or you are off frequency
Notification sounds go out on the air
The radio's sound device is set as the Windows default device
Everything works, but nobody is there
Normal. Check the FreeDV Reporter and call CQ with the voice keyer
Disclaimer. This article is for education only. Follow your licence conditions and local regulations, verify every setting against Icom's manual for your own radio, and operate at your own risk (DWYOR).
Digital Mode · Beginner · about 10 minutes of reading
FreeDV turns an ordinary HF radio into a digital voice station with nothing but a laptop and one USB cable. It is free, open source, and it runs on any SSB transceiver — no vocoder chips, no licence fees, no internet link. This guide explains what it is, how it works, and walks through a full setup on an Icom IC-7300 MK2.
Beginner build · about 20 minutes of reading · total cost roughly $25-35
The 40 meter band (7.000-7.200 MHz) is the workhorse of amateur radio. By day it reaches across a region, by night it crosses oceans. And the antenna that works best for it is also the cheapest antenna you can build: a half-wave dipole made from wire, rope, and a piece of PVC pipe.
Pernah ikut special event seperti 8A100K, tetapi masih ingin tetap memakai call sign pribadi di JTDX atau WSJT-X? Daripada bolak-balik mengganti My Call di menu Settings, dan berisiko salah call sign saat QSO, lebih praktis membuat beberapa profil terpisah. Satu profil untuk satu call sign, masing-masing dengan setting dan log sendiri.
Caranya cukup menambahkan satu perintah, --rig-name, pada shortcut JTDX/WSJT-X. Panduan ini berlaku untuk Windows.
Antenna basics in the context of wireless telegraphy, such as those found in the Wireless Telegraphy Manual for HM Fleet, typically cover several key concepts:
A dipole antenna is one of the simplest and most widely used types of antennas in amateur radio. It consists of two identical conductive elements (often wires) that are oriented in a straight line. The antenna is usually fed at its center, where the transmitter or receiver is connected.
Pernah ikut special event seperti 8A100K, tetapi masih ingin tetap memakai call sign pribadi di JTDX atau WSJT-X? Daripada bolak-balik mengganti My Call di menu Settings, dan berisiko salah call sign saat QSO, lebih praktis membuat beberapa profil terpisah. Satu profil untuk satu call sign, masing-masing dengan setting dan log sendiri.
Caranya cukup menambahkan satu perintah, --rig-name, pada shortcut JTDX/WSJT-X. Panduan ini berlaku untuk Windows.
My late father, YC1BRN, is the reason this station is on the air. His call sign is silent now, but his love for radio carries on in every contact we make from this shack.
His love for radio began as a student at STM Budhaya in Jakarta. A school practical — building an FM transmitter with vacuum tubes — sparked a joy that turned into a lifelong hobby.
Before long he was building his own transmitter at home, quietly broadcasting songs late at night without a licence. Over the years that passion became more focused, and official: he was licensed as YD0WWC, became YD1BRN after moving to Bekasi, West Java, and finally YC1BRN — the call sign he held until the end of his life.
