Posted on

Bourns Optical Rotary Encoder PCB

I purchased a Bourns ENA1J serial rotary optical encoder. This control has a nicely weighted shaft that uses ball bearings. It is rated for >= 10 million rotations. The ENA1J outputs beautiful square signals (unlike mechanical rotary encoders). I think I paid USD$35 for this premium part. You will find optical rotary encoders on high end radios like the Elecraft K3 and professional mixer boards.

I designed a pcb that takes the quadrature output of the ENA1J into INT0 and INT1 inputs of the  ATMEGA328P mcu. A pin header gives access to the I2C bus that allows this to be used as a satellite peripheral.

encoder pcb

Posted on

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

Posted on

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

Posted on

3S lipo batteries for KX3

There was some recent discussion of using 3S (three cells in series) lipo batteries with the KX3 on either the NASOTA Yahoo group or the QRP-L list (I can’t remember). The gist is that the KX3 will keep running with a lower input voltage. A fully charged 3S battery will provide 12.6V. To get ten watts output, you need 12-14V, but closer to the 14V.  Less than 12V,  the KX3 drops to 5W power output.

I was browsing the HobbyKing website for 3S batteries and discovered they offer pickup at a few discrete locations. One of these locations is in Tualatin, OR. This is close enough to warrant save the $7 on shipping.

 

 

 

Posted on

MagicBox Automatic T/R Switch for QRP Radios

I’m ashamed to say that I’ve had this kit in the manila envelope since I purchased it three years ago. I’m finally at the point where I could really use the capability of switching in/out a transmitter. This is catalyzed by playing with the SDRplay and thinking about using it as half a transceiver.

The kit is straightforward thru-hole assembly. I’m thinking I will probably outsource the drilling of the front panel to a friend who has better accuracy than me 🙂

Posted on

Oak Hills WM-2 QRP Wattmeter

I decided to add a small water meter to my bench. The WM-2 caught my eye as it is made in the USA and boasts 5% accuracy. This little meter will from 5mw to 5 watts. It owns a gorgeous analog meter on its front. I wish my photography would do it justice; turns out its really hard to photograph analog meters because of the reflections and shadows.

The WM-2 comes as a kit. It’s just a handful of parts and can be assembled in a few hours.

WM2 side WM2 inside WM2 back WM2 front