AE7EU – uBitx

Pictures: Front panel: Headphone, Microphone, Encoder (from uBitx kit), 4 pushbuttons, AF gain, uBitx standard display.

Rear Panel: +8V input, +12V (or ‘PA’) input (switchable), RF output, Teensy micro USB (CAT), PTT, Key, DSP Audio (from Teensy3.2), Linear control.

Martin AE7EU provides a detailed update on getting his “top board” working:

1) Mechanical clearances are okay. Front panel mic/headphones need to move up by about 0.15″ to be flush to the encoder/display level

2) .1″ headers are misaligned, just needs adjusting in the gerber files, shouldn’t be too bad. Big ‘PITA’ will be wiring directly to the uBitx on the first run for power, and since I only care about single power supply, this mod will only be roughly tested.

3) Messed up on a few pin headers on the front panel; mostly in that the pins from the AF gain resistor interfere with the main PCB, requiring that they be sanded down. A 0.062″ move is all that’s needed.

4) BoM was heavily not optimized. Optimized out a bunch of components to make everything 50-ohm, 1k, 2.2k, 5k, 10k, and 100k resistors, 0.01uF caps (minus one required 1000pF cap), and removed a bunch of 0.01uF caps that can be replaced with capacitor arrays, but some testing with the new values will need to be done. Board is populated with optimized values.

5) Footprint for HC595 is incorrect, but usable. Too narrow footprint, component wider. Failure due to rushing out the door with the design before checking the footprints on a printout (didn’t have the component in hand).

6) Display module is actually the limiting factor for overall height. A smaller display module, and the whole thing could fit in 1.25 (right now, designed for 1.5″)

7) PA Gain cutout is slightly off; still useable with a phillips head screwdriver though.

8) Incorrectly specified Aluminum electrolytics; changing to TH in next design, all 10uF

9) Found the RTC battery was almost fully discharged… will have to check out current consumption when not plugged in, it’s probably trying to run the CPU full tilt.

10) Need to change $1.5 PV36W 20-turn pots to 3/4 turn TX33 pots ($.10 each or whatever)

11) Optimize mods comes next after powerup and verification.

12) Need to verify winding orientation of the SWR bridge

Reference

Martin Held AE7EU has been very busy designing a top tier board for the µBitx main board.

The board interfaces via the standard connectors to the main board of the uBitx. Martin’s top board adds essential features, such as speech compression, an integrated Teensy 3.2 processor, an attenuator and an auto antenna tuner. The front panel break-off from the board simplifies construction and makes the form factor as small as possible.

We look forward to seeing Martin’s report on how the board performs in practice. It is likely we will see a few changes to the board before it becomes available to purchase!

In a post to the BITX20 list Martin identified four options for release:

1) Release the board files, schematic, design files/gerbers, BoM and let someone in China clone it, walk away.
2) Same as #1, but just sell bare PCB’s.
3) Sell PCB’s with all SMT components installed, and a baggie of TH parts, toroids, and couple feet of magnet wire.
4) Sell the entire thing fully assembled ($$$).

It is likely that either options 2) and 3) will be favoured by the amateur community, based on initial feedback to Martin.