Category: Repairs

How to set the bias

How to set the bias

Siegfried Jackstien, DG9BFC

  1. Set both the POTS to minimum current
  2. Select Mode as USB. Reduce the MIC to zero.
  3. Press the PTT.
  4. Without speaking into the microphone, carefully increase the DRIVE_BIAS POT until the current increases by 200 mA. Note the current.
  5. Keeping the PTT on the microphone pressed, now increase the PA_BIAS POT until the current increases by another 200 mA.
  6. Release the PTT.

Eliminating Periodic Noise in the Speaker (Developer Edition)

Eliminating Periodic Noise in the Speaker (Developer Edition)

Ashhar Farhan, VU2ESE

The LM380 audio amplifier is picking up the Wifi RF and it results in a noise that repeats every 8 seconds of so as a series of quick pulses.

The noise is not present if you use earphones as they bypass the LM380 audio amplifier.

The current solution is to just turn off the WiFi and use Ethernet instead for Internet.

Corrupted sBitx – How to reset the settings.ini

Corrupted sBitx – How to reset the settings.ini

Anthony Good

Before you replace files, try deleting (or renaming) your settings file, /home/pi/sbitx/data/user_settings.ini.  I have had it several times where upon restart of the app or restart of the Pi, something goes wonky and deleting the settings file fixes it.  I haven’t gotten to the bottom of it yet.

If you need to toss a hand grenade, I would do the following (First open a terminal with Ctrl-Alt-T and then type:)
cd /home/pi
mv ./sbitx ./sbitx.old
git clone https://github.com/afarhan/sbitx.git
cd ./sbitx
./build sbitx
./sbitx