Picardy 2020
============

A reinterpretation of the [Picardy 2m SSB transceiver](http://f6feo.homebuilder.free.fr/transceiver_PICARDY.html) by F6FEO
combined with the [Anglian 3L transverter](http://www.g4ddk.com/Products.html).

* Designed in KiCad
* Meant to be used with a microwave transverter
  * But also stand-alone 28MHz and 144MHz (The IF bands)
* Using a STM32F103C8T6 controller
  * Si5351 clock source (generates 3 clocks)
  * An LCD display
* Discarded ideas
  * Include a Lars Widenius GPSDO originally published on [eevblog](https://www.eevblog.com/forum/projects/lars-diy-gpsdo-with-arduino-and-1ns-resolution-tic/?all)
  * Offer a 10MHz output refclk for a transverter
  * Instead, have a 25MHz ref input, and use a LeoBodnar reference

* Very good [explanations](https://groups.io/g/BITX20/topic/si5351a_facts_and_myths/5430607) about DDS vs DPLL from Hans Summers

TODO before ordering the PCB
============================

* Microphone input
  * Verify microphone pinout for MH-42

* CW
  * Does the trick with the DC bias to leak the LO work ?
    * Not tested, but plan B done (J306)
    * Use an additional PWM output for plan B?
  * Put sidetone volume setting before RV303?
    * Hook up to LM375 BYPASS?

* Si5153
  * Check desired frequencies can be achieved:
    * clk0: LO1 = 28 - 4.9152 + VFO
    * clk1: VHF-LO = 144 + 28 and 144 - 28
    * clk2: BFO = 4.91521
    * See `freqplan.py`
  * If not, generate LO1 and BFO with Si5153, and connect an external LO to the VHF LO u.FL
    * No 116MHz crystals on mouser, but 114.285MHz are available, HF bandpass filters recalculated.

PCB Assembly Plan
=================

1. DCDC converter for 8V and LDOs
  * Check output voltages
  * Check drop under load

2. STM32F103C8T6
  * Programming
  * Sidetone low-pass
  * Probably need to do a UI proto already

3. Si5153
  * Check I2C works

4. 8V and 5V relay
  * Check switching with microcontroller and validate resistors

5. Baseband
  1. Crystal filter shape
  2. RX and TX filter shape
  3. Receive path: IF mixer, crystal filter relay, IF AGC, BFO mixer, AGC measure, AF amp, SPKR
    * Verify LO levels into SA602A: at least 200mVpp
  4. Transmit path: Mic amp

6. Anglian
  1. LO filter shape
  2. LO amp. Mixer needs +7dBm
  3. All passives
    * Verify correct voltages for amplifiers
    * Verify PIN currents (Between 20mA and 60mA, below 0.8V)
    * Verify filter shapes
  4. IF amplifiers, both RX and TX
  5. VHF amplifiers
  6. VHF bandpass filter
  7. Mixer

7. External switching relay