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diff --git a/README-Picardy2020.md b/README-Picardy2020.md new file mode 100644 index 0000000..e2dc30b --- /dev/null +++ b/README-Picardy2020.md @@ -0,0 +1,170 @@ +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). +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. + |