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authorMatthias P. Braendli <matthias.braendli@mpb.li>2023-03-10 15:38:08 +0100
committerMatthias P. Braendli <matthias.braendli@mpb.li>2023-03-10 15:38:08 +0100
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-Picardy 2020
-============
+Picardy 2020 and DART-70
+========================
-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).
-Additional inspirations: uBitx, the KN-Q7, LimeRFE and EI9GQ's "Building a Transceiver" book. Many thanks to all the
-designers behind these projects.
-
-The hardware design is licenced under the "CERN Open Hardware Licence Version 2 - Permissive", see *cern_ohl_p_v2.txt*.
-The firmware is MIT-licenced.
-
-* Designed in KiCad
-* Meant to be used with a microwave transverter and stand-alone 144MHz
- * For transverter usage, no PA reduces current consumption.
- * For stand-alone, see MMRF1021 amplifier below.
-* Using a STM32F103C8T6 controller
- * Programmed in [Rust](https://rust-lang.org/)
- * Si5351 clock source (generates HF 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 an external reference
- * Use the Si5351 to generate the VHF LO at 116 MHz
- * It wasn't clean enough, so a separate [XTAL LO board](./lo_board/) was designed
- * With a 114.286 MHz crystal, we get a first IF of 29714 kHz
-
-*First QSO done with this transceiver and MMRF1021 amplifier on 2020-12-07*
-
-On RX, an [LNA4ALL](http://lna4all.blogspot.com/) LNA was used. On TX, 2x SPF5189Z, a bandpass filter to remove the LO,
-and the [MMRF1021](http://git.mpb.li/git/mmrf1021-pa/about/) amplifier were used, giving about 200mW output power on the
-very first trial.
-
-Later, the external bandpass and 2x SPF5189Z were replaced by an internal bandpass with less insertion loss and a single
-SPF5189Z.
-
-
-*First 3cm QSO done with Picardy 2020 as IF transceiver on 2020-02-21*
-
-Using a Downeast Microwave 10368CK transverter.
-
-
-TODO
-====
-
-* Where does the 1.6kHz offset come from?
-
-Open questions
-==============
-
-* 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 LM386 BYPASS?
-
-Issues
-======
-
-* Coupling between VHF filter coils was way too large
- * Fixed, replacement of coupling caps.
-* SEQ0 is used in inverted-logic in baseband, and noninverted for power relay
- * Due to inconsistent naming
- * Ugly fix on K603 side, use SEQ0n, SEQ1, SEQ2
-* G6K-2F-RF all have the Y footprint, not the equidistant one.
- * And they have additional GND flaps too, which are not in the Kicad footprint library
- * Can be kludged-in
-* 5V jumper is less useful as hoped
- * Intention: disable VHF stuff
- * Unintended effect: removes LCD backlight
-* C319 and C326 are redundant
-* BC856W wrong footprint
-* R327 upsets DC offset of audio amp, added 2.2uF capacitive decoupling in series with 1k
- * PTT makes loud click, assemble with 100nF only, still loud
- * Connected LM386 back to 8V, through 0 Ohm instead of 10 Ohm (was on 12V through 10 Ohm because DCDC noise). Still
- loud.
- * Investigate other muting schemes.
- * Connecting BYPASS to GND generates click
- * 2N3819 based muting according to G3YCC works better.
- * Assemble 1k + 100nF for coupling, revert to 12k for R329, use 20k for R326 to slow down the transition a bit
-* 2m LPF from LimeRFE use values I don't stash
- * 20pF done with 2x 10pF
-* SW: ADC input for buttons looks messed up...
- * Four buttons instead of 7 are enough anyway
-* Connect 3V3 LDO to 12V directly
-* Also, replace DCDC by L7808 to improve spectral purity
- * Actually there would be more to be gained with a DCDC on 5V or 3V3!
-* Added a LM360T LDO for the MMRF1021 so that it can be powered from 3S LiPo (11.1V) and Pb (13.8V) batteries
-* Add 2.2uF caps near consumers
- * Replace C535, C536
- * Replace C343, C315
- * Next to R508
- * Next to R305
- * Parallel to C331
- * Parallel to C607
- * Next to R306
- * Next to R504
- * Next to R328
- * Next to R515
-* Reduce RF coupling
- * Added 100pF caps on microphone connector and CW input
- * Added 22pF on DC jack, DIN
-
-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
- * Crystal filter shape
- * RX and TX filter shape
- * Receive path: IF mixer, crystal filter relay, IF AGC, BFO mixer, AGC measure, AF amp, SPKR
- * Verify LO levels into SA602A: at least 200mVpp
- * Transmit path: Mic amp
-
-6. Anglian
- * LO filter shape
- * LO amp. Mixer needs +7dBm
- * All passives
- * Verify correct voltages for amplifiers
- * Verify PIN currents (Between 20mA and 60mA, below 0.8V)
- * Verify filter shapes
- * IF amplifiers, both RX and TX
- * VHF amplifiers
- * VHF bandpass filter
- * Mixer
-
-7. External switching relay
-
-
-Tuning
-======
-
-IF gain (R307)
-
-Define if we need C361, C360
-
-Ensure LO1 and BFO voltage level at TP301 TP302
-
-
-
-Additional remarks
-==================
-
-Very good [explanations](https://groups.io/g/BITX20/topic/si5351a_facts_and_myths/5430607) about DDS vs DPLL from Hans Summers
-
-Si5153 test before PCB fab:
-
-* It seems the desired frequency plan can be achieved:
- * clk0: LO1 = 28 - 4.9152 + VFO, i.e. from 23 to 25
- * clk1: VHF-LO = 144 + 28 and 144 - 28, i.e. 116 MHz
- * clk2: BFO = 4.91521
- * See `freqplan.py`
-* This ended up being too noisy and was replaced by an external VHF LO, with LO1 and BFO generated with Si5153
- * No 116MHz crystals on mouser, but 114.285MHz are available, HF bandpass filters recalculated.
+This repository contains design files and firmware for both the Picardy 2020 2m SSB/CW transceiver
+and the DART-70 4m SSB/CW transceiver designed in 2023.
+Please see [README-4m](README-4m.md) or [README-Picardy2020](README-Picardy2020.md) for more details.