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@@ -3,40 +3,21 @@ 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
+See dart70-blockdiagram.pdf
+
* Enclosure: Hammond 1411R or 513-0900?
+Receive gain:
+
+S9 is -93dBm, S1 is -141dBm
+
+-141 -1 +16 -1 -7 -4 +60 -7 +30 = -55 dBm
+
+
+Transmit gain:
+
+-6 -7 -4 +16 -4 -7 -1 -1 +15 +15 +15 -1 = 30 dBm
+
## To order
* Enclosure