RXP2600: Contest TCVR - HIGH Performance CW only

Superhet + SDR

9 Mc IF + 2 xAD603 + FST3125 IQ detector

H-mode mixer

FSA3157 +  ET1-6TSM20

Low cost D.D.S.

Si5351 + custom low pass filters

Hilbert digital F.I.R.

Teensy 4.1 with custom code.

Digital sampling A.G.C.

Arduino nano + AD8307

7 or 10 " touch display.

Nextion display + own code

Kenwood code emulator

N1MM interfacing 

Part 1 - Local Oscilator

Si5351 + Low pass filters + Autolevel @ 0,5Vpp.

  • Si5351 is not the greatest PLL in the world, but is cheap and accessible.
  • Output signal is not sinewave but almost rectangle, and lots of strong harmonic signals visible on output. 
  • Easy to use on arduino code style, easy to manipulate it but strongly advice against using more than 1 output to avoid crosstalking.
  • Fix 1: Ad603 with 40dB gain driven by MCP4725 via i2c bus  for autolevel
  • 6 x low pass filters, one for each TX band and another 3 for RX + 9 Mhz IF  
  • More than 60 dB harmonic rejection.
  • Reed relays for switching instead of diodes.

Part 2 - Bandpass filters, RF Mixer and 15dB Preamp / ATT.

  • 6 bandpass filters, Chebyshev 5th order.
  • Relays switching 
  • 15 dB Att or 15 dB Preamp.
  • FSA3157  H-Mode Mixer Module

Part 3 - 9 Mhz I.F. + IQ Detector

  • 2 x AD603, 80dB gain + AGC line
  • 1 x 600 Hz IF crystal filter
  • 1 x 3 Khz  Noise crystal filter
  •  1 x 15 dB postmixer preamp with an old 2N5109 
  • 2 x FST3257 IQ detector
  • 2 x AD8599 audio preamp and 0-200 Hz cutoff filter
  • Teensy 4.1 m.c.u. with 2 x 200 Hilbert coefficients I/Q for LSB / USB side suppresion.
  • SI3551  2x 9Mhz @ 45 degrees offset. 

Part 4 - Audio codec, MCU board - To be continued

  • Arduino DUE MCU 
  • SOTA BEAMS VARI  DSP
  • AD8703 logarithmic ACG detector
  • Noise pulse detector and gate for N.B.
  • Noise reduction 
  • Kenwood TS520 CAT codes emulator for N1MM.
  • Nextion 7″ touch screen display

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