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Si5351 PCB with Low Pass Filter

In today’s mail, the latest revision to my Si5351 board arrived from pcbs.io. For me, this board is really a prototype and proof of concept. It is a reusable building block. This module is streamlined I can import it into a larger design in KiCad, remove the headers, and go. The low pass filter is really designed for HF work. One could change the values and reformulate the lpf.

After the kids go to bed, I salvaged the parts from the last generation board and assembled one. It is always thrilling when it works right off the bat. This generation fixes a VCC problem, adds additional bypass capacitors, an extra [optional] header for using outputs two and three. Lastly, lots of markings (documentation on the board).

si5351 rev1b top si5351 rev1b bottom

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Build Log: Starting the MiniKits M1 Transceiver

This past summer, I ordered a MiniKits M1 modular transceiver kit. This kit packages each section onto a separate circuit board, for future modifications. Work at on1 was super busy, so I put off assembling the kit until the Christmas holiday. I did not purchase the MiniKits PIC based control and DDS system. I am going to use a si5351 with an Atmel ARM chip for digital control. I had pcbs.io manufacture a pcb with a super nice Bourns optical encoder for the main frequency dial.

The modules I purchased are:

  • EME208
  • EME207-20m
  • EME207-40m
  • EME211
  • EME209-19m-30m
  • EME206
  • EME210
  • EME201
  • EME202
  • EME203-9m-2.5k

 

m1 transceiver

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Filtering the Si5351 Output

I’m working on building blocks that can be used for larger designs. One of those building blocks is a DDS signal generator using the Si5351. I added a low pass filter to the output of CLK0. This filter starts rolling off at 50mhz. Elsie generated the schematic and I normalized the values to smd capacitors I had and Murata rf chip inductors I purchases.

si5351 filter schematicL1, L2, and L3 are smd inductors that cost about USD$0.20 each.

Here is what the Si5351 output looks like with Adafruit’s example library sketch.

si5351 filter before2This is the output after the low pass filter. Second and third harmonics are still there, but there is definite improvement.

si5351 filter after