Saturday, 31 July 2021

PortsLang 4 Hardware Updates

 Having used the PortsLang 4 for a while I decided it needed 3 main improvements:-

1. The mouse for tuning works ok but is a bit clumsy and occasionally misses pulses

Fitting am Arduino Pro micro board emulating a USB mouse s described  at  with an Optically coupled encoder fixed this issue in my Langstone so the technique would be used again, There is not enough room for a turning knob on the Front panel. An external solution would have to be used.. The mouse simulator was built with 3 switches an an optical encoder in a small diecast box, allowing it to be plugged into the back panel of the PortsLang

2. The Adalm Pluto Oscillator drifts and has a frequency offset

This is not an issue in my Langstone as it has enough room to put a good oscillator and multiplier in the box.  There isnt enough room in the PortsLang to do that. Measuring the output frequency of the PortsLang showed the oscillator settled down 33kHz high at 437 MHz which was unacceptable. I had previously bought a couple of  the recommended replacement 40 MHz oscillators from Mouser, so decided to swap it out. The existing oscillator was carefully removed from the PCB with two soldering irons and the new oscillator soldered in place . Unfortunately when removing the original oscillator solder flicked onto the oscillator output capacitor and whilst removing this solder the capacitor vanished. A new 18pF 0402 capacitor , While I had the board out I also added the PTT output relay described at

Measurements now showed the oscillator was now within 200 Hz at 437MHz without tweaking the Pluto calibration.

3. It has no speaker so a headset HAS to be used to listen

I had built a speaker into my Langstone so I could hear the signals when peaking a dish without tripping up on the headset lead. There was not enough room for a speaker in the PortsLang so an external box  was needed. Looking in my Junkbox I found a 12V 18W audio amp module, volume control,  a 2" speaker and a suitable plastic box, I built the amplified speaker with a DC connector to allow it to be powered from a 12V output from the PortsLang 

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