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Icom IC-7300 & IC-7300 Mk II

The IC-7300 is one of the most popular rigs in the POTACAT community, and everything — CAT control, PTT, TX/RX audio, even remote CW keying — rides the radio’s single built-in USB cable. The difference between rock-solid and flaky comes down to a handful of radio-side menu settings, so start here.

This page also covers the IC-7610, IC-7100, and IC-706MKIIG at the bottom.

Quick setup

  1. Add a new rig and select the IC-7300 (or IC-7300 Mk II) profile.
  2. Choose the radio’s COM port (it enumerates as a Silicon Labs CP210x device on Windows).
  3. Match the baud rate in POTACAT to the radio’s CI-V USB Baud Rate — 19200 is the sweet spot (see below).
  4. Set the rig’s RX and TX audio devices in POTACAT to the radio’s USB Audio CODEC.

Radio-side CI-V settings

Open MENU > SET > Connectors > CI-V and set:

SettingValueWhy
CI-V TransceiveOFFThe big one. When ON, the radio’s own status chatter collides with POTACAT’s commands on the CI-V bus — the classic cause of PTT that only keys one try in three.
CI-V USB Baud Rate19200 (fixed)See the trade-offs below.
CI-V USB Echo BackOFFWith it ON, PTT gets intermittent and TX audio comes out thin with almost no ALC movement.
CI-V Address94h (Mk II: B6h)Must match the CI-V address in POTACAT’s rig settings.

Note: Restart the radio after changing CI-V settings.

Baud rate: fixed 19200 vs Auto

You wantSet CI-V USB Baud Rate to
Reliable PTT and working FT8 decode in JTCAT19200, fixed, matched on both the radio and POTACAT
CAT power-on from POTACAT/ECHOCATAuto
  • Fixed 19200 is the recommended setting: a fixed rate eliminates CI-V collisions, and JTCAT will not decode FT8 reliably with the radio at 115200. Drop to 19200 on both sides.
  • Auto is what makes the Power On button work. Waking a powered-down IC-7300 requires a long preamble of FE bytes before the CI-V power-on command — per Icom’s manual, about 150 bytes at 115200 baud, 50 at 38400, 25 at 19200 — and with the radio on Auto this wake-up sequence has been confirmed to work. Power off works at any setting; power on is the hard part.

Note: Powering the radio on from a full power-down is still a known rough edge — the radio takes several seconds to boot and the CAT connection can drop before it finishes. If Power On fails for you, keep the CI-V baud rate low (or Auto), or define a custom CAT power-on command: click RIG in the top bar, then CAT.

Stuck in transmit after closing ECHOCAT

If the radio locks into TX when you close the ECHOCAT browser session, check SET > Connectors > USB SEND/KEYING and set USB SEND to OFF. When it’s assigned to RTS, the serial control line can hold the radio keyed after the remote session ends. This is the durable, radio-side fix.

Digital modes: MOD input and levels

  • SET > Connectors > MOD Input: set DATA MOD to USB — some radios default data-mode audio to the ACC jack, which leaves JTCAT/FT8 transmitting dead air.
  • USB MOD Level around 50% is a good starting point; watch the ALC meter during TX and back off if it’s slamming.
  • The radio’s USB audio output must carry AF (normal receive audio), not IF — check the USB AF output setting under SET > Connectors.
  • If ECHOCAT’s RX meter shows clipping, lower the radio’s USB AF output level — some users run it around 10%.

Tip: For JTCAT, some users report good results with the RX slider around 37% and the radio’s AF gain near the 10 o’clock position.

Remote CW keying

Remote CW on the IC-7300 works well, but only over a direct CI-V serial connection — not through rigctld/Hamlib:

  • On direct CI-V, POTACAT sends the radio’s real CW key-down/key-up command (0x1C 0x01) for every paddle element.
  • Hamlib’s rigctld protocol has no per-element CW command — it only exposes the mic PTT line. Keying a paddle through rigctld raises PTT while the radio sits in CW mode: transmitter on, key line untouched, silent TX.

Setup:

  1. Connect the rig as a direct CI-V serial rig (not rigctld Network / Hamlib).
  2. On the radio, set SET > Connectors > USB SEND/KEYING > USB Keying (CW) to USB(A) DTR.
  3. Leave POTACAT’s CW Key Port set to (none) — the 7300 is keyed through its existing CI-V connection.

Warning: Linux users: the kernel’s cdc-acm driver can’t control the DTR pin on the 7300’s USB port (Operation not supported in the log). Worse, the stuck-high DTR line will key the radio continuously the moment it enters CW mode. On Linux, set USB Keying (CW) to OFF to stop the phantom keying. For real paddle keying, wire a cheap FTDI/CH340 USB-serial adapter to the radio’s 3.5 mm KEY jack (adapter DTR pin → tip, GND → sleeve) and select it as the CW Key Port. Note that common “CI-V data cables” are not keying cables — the DTR pin isn’t broken out — and the CW Key Port must be a different COM port than your CAT port.

CW text macros are sent over the normal CAT connection and work everywhere, including Linux.

FLRig as an alternative CAT path

CI-V serial drops commands that arrive nearly back-to-back; POTACAT compensates, but some IC-7300 owners find routing CAT through FLRig smoother — and the internal ATU can be triggered through FLRig, where POTACAT’s direct ATU command doesn’t work on this radio.

  1. Run FLRig with its XML-RPC server on (the default, port 12345).
  2. In POTACAT, add the rig as Other Rig (Hamlib) with Rig Model FLRig, host 127.0.0.1, port 12345. FLRig owns the serial port — leave the COM/baud fields alone.
  3. Alternatively, run your own bridge with rigctld -m 4 -r 127.0.0.1:12345 and use the rigctld Network rig type.

Troubleshooting quick hits

  • Spot clicks stopped QSYing and the CAT badge is red — make sure the WSJT-X Mode checkbox is off unless WSJT-X is actually running and configured.
  • Echo on ECHOCAT — both the audio input and output must be the radio’s USB Audio CODEC, never the PC’s default mic/speakers.
  • Mode flips to USB-D on phone PTT — that’s the SSB-over-DATA feature. If you’re operating with the radio’s own mic, uncheck SSB-over-DATA in Settings.
  • No FT8 decodes — CI-V baud at 19200 on both sides, and check the JTCAT RX slider.

IC-7300 Mk II

  • The Mk II’s default CI-V address is B6h, not the original 7300’s 94h. This is the #1 Mk II gotcha — if you copied settings from an original 7300, fix the address and select the Mk II rig profile.
  • POTACAT cannot connect to the Mk II (or 7610/7760) over the network CI-V/LAN port — Icom’s LAN remote protocol is proprietary. Run POTACAT on a PC or Raspberry Pi at the radio and operate remotely with ECHOCAT, or bridge through wfview/wfserver.
  • Everything else on this page (CI-V settings, USB SEND, CW keying, Linux notes) applies to the Mk II as well.

IC-7610

  • CI-V address is 98h.
  • No TX audio from ECHOCAT/digital modes: set MENU > SET > Connectors > MOD INPUT > SSB MOD to USB1 (or USB2, whichever port your cable is on), and set SSB-D MOD to the same.
  • If Test Connection passes but the radio never QSYs, type the bare COM port name (e.g. COM7) into the manual COM field instead of accepting the auto-detected “Silicon Labs CP210x” dropdown entry.

IC-7100 & IC-706MKIIG (DigiRig)

The same CI-V hygiene applies — CI-V Transceive OFF and a fixed baud rate cure most flakiness on the IC-7100 too.

The IC-706MKIIG (CI-V address 58h) has a firmware quirk: it accepts CAT PTT but doesn’t route TX audio to the rear interface, so PTT must be keyed on the DigiRig’s hardware PTT line instead:

  • Set the PTT Port field in the rig’s Hamlib settings (Settings > Rig).
  • Two-port DigiRig: CAT on one COM port, PTT Port on the other COM port.
  • DigiRig Mobile (single port): CAT and PTT share one COM port — use the DTR/RTS pin selector (default DTR; some units key on RTS).