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diff --git a/README-4m.md b/README-4m.md new file mode 100644 index 0000000..020aeee --- /dev/null +++ b/README-4m.md @@ -0,0 +1,42 @@ +DART-70 +======= + +In 2023, the 70MHz band became accessible to amateurs in Switzerland. This offers an excuse to build a transciever. + +* Separate things a bit more than on Picardy 2020 + * One HF SSB/CW exciter PCB with: + * Voltage regulators + * Mic input from Picardy 2020 + * AGC measurement like Picardy 2020 + * AGC IF amp better than Picardy 2020 + * VEXIBITX applies AGC at HF input instead, and uses uBitx amplifiers for IF + * uBitx has no AGC + * Hybrid Cascode? (Implies IF between 8 and 12 MHz) + * Frequency plan: + * What HF intermediate frequency? + * High-side mixing? need low-pass to reject image, also rejects FMBC + * 96MHz oscillator: 26MHz IF + * Low-side mixing (kuhne and anglian do that) + * 42MHz oscillator: 28MHz IF + * Prefer, can't be wrong if others do that + * Reuse Anglian 3L oscillator from lo_board/lo_board.pro + * VFOs Si5351A-B-GT for first two mixers + * Mixers (3 needed: VHF, HF, AF) + * AF: like VEXIBITX + * HF: like uBitx (BAT68-04W ring mixer, see doc/ubitxv6.{txt,pdf}) + * VHF: MCL RMS-11X (+7dBm LO) or the macom one? (missing from inventory) + * XTAL filter QER like uBITX at 11.0592 MHz + * One PCB with HF-4m transverter, inspired by Anglian + * One PCB with 4m driver, PA and antenna switching + * We are allowed 25W ERP, aim for 10W PEP + * BCW71 driver, 2SCR573D3 push-pull amp? + * How about STN4NF20L? + * LNA: SPF5189Z + * One PCB for frontend + * Connected by cable to the main board + * Microcontroller, Display, Encoder +* Enclosure: Hammond 1411R or 513-0900? + +## To order + +* Adafruit 292 and an i2c display |