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Configure transmit safely

Transmit features can key connected station equipment. Confirm your radio, antenna, frequency, mode, and local authorization before every transmission.

Radio Bench transmit features cover HF and the 6 m band. Band presets and plans do not enforce your license privileges. Check that each frequency is within your privileges.

Configure audio

Complete first reception before commissioning transmission. Keep the radio at low power into a suitable dummy load for the first RF check.

  1. Open Settings > Audio.
  2. Under RECEIVE OUTPUT, set Output device to your headphones or speakers.
  3. Under MICROPHONE, set Input device to the microphone you will speak into.
  4. Under TRANSMIT OUTPUT, set Output device to the audio interface connected to the radio's modulation input.
  5. Speak normally and check the microphone meter.
  6. Adjust Input gain so speech registers clearly without clipping.

The input meter checks captured microphone level with input gain. It does not establish processed speech quality or radio output. Check operating-system microphone permission if the input remains inactive.

Adjust speech processing

Select USB, LSB, AM, or FM. Open TX AUDIO in the left control column.

Section Controls Starting adjustment
Input Input gain and Noise reduction Set clean microphone level, then compare noise reduction on and off.
Processor Compressor, Bass, Treble, and mode-specific filtering Start with compression off and neutral tone. Change one control at a time.
Monitor The Monitor switch and its Volume Use headphones at a low level when monitoring transmitted audio.

Use TX mic preview to compare processing with the same recorded sentence. Its listening volume does not set TX drive.

The compressor meter shows gain reduction, not RF power or the radio's ALC. Increase compression only while intelligibility improves. Check the Audio workspace for clipping and avoid sustained output limiting.

Check the output route

Return to Settings > Audio > TRANSMIT OUTPUT. Start with a low Output level. The radio must use the connected audio interface as its modulation input.

Play tone sends a two-second test through the TX output gain path. It bypasses microphone and speech processing. It does not assert CAT PTT, but a radio using VOX can transmit when the tone arrives.

Only run the TX tone when the station is prepared for that possibility. Watch the TX output meter for activity and clipping. Reduce Output level if the path clips.

Check Establishes Still needs checking
RX tone Listening output works Source reception and tuning.
Microphone meter Microphone capture and input gain work Processed speech and TX routing.
Speech preview Processing can produce intelligible audio at RX output Radio input, PTT, and RF quality.
TX tone Selected TX output delivers test audio Speech processing, physical keying, and RF quality.
Independent RF monitor The actual emitted signal Interpret it with the radio's power and ALC indications.

Configure PTT

Connect CAT if Radio Bench must key the transceiver. Configure the rig mode preference and its data input together.

Without CAT, an external VOX arrangement can key the radio from transmitted audio. Radio Bench cannot confirm that physical keying occurred.

Space toggles ordinary PTT. Releasing the key does not stop transmission. See the PTT shortcut for focus rules and changing the key.

Status Meaning
TX ACTIVE CAT acknowledged PTT, or the rig reports PTT active. This does not prove RF power or correct modulation.
VOX ACTIVE Audio is being delivered to TX output. Radio keying is unconfirmed.

If CAT fails during transmission, check the radio directly. A disconnected control link cannot guarantee that a stop command reached the rig. Restore reception and the control connection before trying again.

Check the operating state

Confirm that the rig mode matches the selected Radio Bench mode. Confirm that the TX output goes to the radio, not to loudspeakers.

  1. Confirm the selected mode, actual rig frequency, modulation input, and low power setting.
  2. Start ordinary PTT and speak a short sentence.
  3. Check Radio Bench's TX status and audio meter.
  4. Check the radio's transmit indication, power, and ALC.
  5. Stop PTT and confirm that the radio returns to receive.
  6. Monitor the emitted signal with suitable independent equipment before normal operation.

Reduce TX output or the radio's input sensitivity if the signal is overdriven. Clear audio in preview alone cannot establish a clean RF signal.

IC-7300 USB example

This example uses CAT keying and USB audio in data mode.

On the radio, open MENU > SET > Connectors. Set DATA MOD to USB. Under CI-V, unlink the USB port from the remote port and set its baud rate to 115200. Use the default radio address, 94h, for this example.

In Radio Bench, select the IC-7300 model, its serial port, and matching baud rate. Connect CAT and select Track. In Settings > Rig Control > MODE CONTROL, set Radio Bench may set to Data.

In Settings > Audio, select the radio's USB sound device under TRANSMIT OUTPUT. Select your speech microphone under MICROPHONE. Select USB for a USB-D test. Verify the radio's displayed mode.

Adjust the Radio Bench Output level and the radio's USB modulation level during the low-power test. The correct drive depends on your audio-device settings. Do not assume a fixed percentage is correct.

FT8/FT4 transmissions

The FSK workspace generates timed transmit audio. It does not use the microphone to construct FT8/FT4 messages. Configure the output connected to the radio and verify the data input and CAT/PTT path.

Use the FSK contact controls to start a scheduled exchange and Halt to stop it. Do not treat ordinary voice PTT as the FSK start control.

Remain present and supervise every exchange. Robotic or unattended FT8/FT4 QSOs are not permitted in Radio Bench.