MicroHam Audio Levels

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N1MM has a built in DVK, which uses the sound card. Here are the procedures I use to set the audio levels with the MicroKeyer interface.

General Info

MK Preamp

We use Heil Headsets, so you need the internal MK Preamp. Open the case and change the jumpers on the daughter card. There are markings on the daughter card to guide you. Preset the knobs on the MK to 2 o'clock. Close the case. You can diddle the control from the outside, if needed.

Audio Routing

In general, there are two audio routes in the MK (A or C). Look at the drawing on the Audio Switching Tab of the MK Router software. The routes are as follows:

  • A - Audio routes through the computer
    • mic => MK preamp => sound card (mic/pink) => computer => sound card (line out/green) => rig
  • C - Mic audio routes directly to the rig (mic connector)
    • mic => rig

We're not interested in Route C.

Audio Routing Diagram

The interplay between the Windows audio control panels (REC and VOL) can be tricky. The diagram below shows the various MicroKeyer modes, routing and relationships to the audio control panels. The diagram shows a SIP Phone interfaced to the sound card. (The SIP phone is registered with an Asterisk PBX, which allows both TX and RX audio to be accessed from any phone, IP or PSTN.)

MH Routing.png

MK Audio Switching Tab

The sliders in the MK Audio Switching tab:

  • The REC slider sets the audio level for recording WAV files
  • The TX slider adjusts the audio going to the RIG in mode A
  • The TX Voice/Digital adjusts the audio from the WAV files. (computer to rig)

Since we're using the internal MK preamp, make sure Mic Boost (+20db) under Microphone in the Record Controls is unchecked.

Adjustment Procedures

There are two basic steps:

  • Adjust the radio using a directly connected mic
  • Adjust the audio coming from the computer

Step 1 - Adjust the audio controls on the rig with a direct microphone connection

  • Select Audio Route A in the audio switching TAB for all PTT modes
  • Turn off the Processor, talk through the boom mike and adjust the mic gain so the ALC engages - Mic Gain = 50 on the TS2K
  • Turn ON the processor, talk through the boom mike and adjust the compressor for 10db - Proc IN = 40

Step 2 - Adjust the audio controls using audio from the computer

Change the routing on the audio tab to mode C. This routes the audio from the mic, through the preamp, through the computer into the radio's microphone. It also allows the record WAV files to play back from the computer to the radio. (See the drawing on the MK Router Audio Switching tab.)

Select the sound card and ensure the settings are as follows:

REC-MIC - Microphone (change to something else after testing)
TX-MIC - Microphone 
TX VOICE/Digital - Wave
RX RECORDING - none, not used
  • MK Audio Switching Tab/TX Mic Slider - controls the audio fed from the computer to the radio
    • set for half scale
    • Press the footswitch and adjust the internal POT in the MK so the ALC reacts the same as the directly connected microphone. Once this is set, leave it alone.
  • MK Audio Switching Tab/Wave Sliders - controls the DVK audio playback volume from the computer to the radio
    • Set the right hand slider to 100 and uncheck Stereo
    • Set the left hand slider to 0
    • Press the Test Signal button to generate a tone.
    • Adjust the left hand slider until the ALC engages and you have the correct RF TX levels
    • Press the Test Signal button to stop the tone
  • MK Audio Switching Tab/REC-MIC - This is volume control for recording DVK messages.
    • Make sure Mic is selected as the input on the REC Control
    • Talk and adjust the Mic slider so the signal red lines on peaks.
    • Now change the device to something unused, to give the mic to N1MM
  • Now test a DVK message
    • In N1MM, use Ctl-O to set the operator (e.g. Ctl-O and type W7IY) The wave files will be stored in a subdirectory with this operator identifier (e.g. W7IY)
    • Record a message in N1MM (SHFT-CNT-Fx Starts recording, SFT-CNT-Fx ends recording.
    • Play back the message (e.g. F1) and adjust the TX Voice Slider (WAV Device) so the ALC reacts the same as the directly connected mic
  • The audio levels should be equalized. The overall levels can be adjusted with the Play Control slider (Play Control) or the MASTER Wave slider under TX Voice. It can also be adjusted with the Radio knob on the MK.
  • Save the preset (MK Router - Preset/Save)


So far - the vast majority of the problems have been solved by ensuring the cables are correct and that the Microphone is selected in the Record Controls (Rec Mixer.) After that, it's all about the levels. We have a tendency to overdrive things. So chill out.

  • Make sure the cables are connected to the correct ports.
    • Mic - Pink
    • Line Out - Green
    • Line IN - Blue (not really needed.)
  • Try the Audio Recorder under Accessories
  • Make sure the TX monitor is on in the rig to listen to the transmitted audio
  • Don't over drive things!
  • Use the 'Test Signal' button in the MK Audio Mixer Tab. If it doesn't produce a sound, check the TX Voice device - should be Wave, check the volume controls, check the cables.
  • Go back to audio route C - which routes the mic directly to the rig.
  • Make sure the MK preamp is adjusted properly (Mode C - affects the TX audio levels.) Fully CW is minimum level. Don't overdrive.