Kits and Parts Lowpass Filter

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Kits and Parts Universal Filter Board

CWAZ filter

Other References and Topologies

K&P Schematic

LPF.1.5.sch.png

K&P PCB

LPF.1.5.pcb.png

CWAZ 40M, 7 MHz Filter

SPICE Simulation

  • GitHub repo
  • -6 dB at 7 MHz
  • -68 dB at 1st harmonic (14 MHz)
  • -75 dB at 2nd harmonic (21 MHz)

CWAZ LowPass7MHz SPICE.png

CWAZ LowPass Values.PNG

T37-2 Inductors

INDUCTANCE - L1, L3

  • Desired: 1.34 uH
  • Calculated: 1.3 uH (97% of desired) Turns required: 18
  • CORE
  • Part number: T-37-2 (Red)
  • Frequency Range: 1 to 30 MHz
  • u: 10
  • AL: 40 uH/100 turns

INDUCTANCE - L2

  • Desired: 1.22 uH
  • Calculated: 1.2 uH (95% of desired) Turns required: 17
  • CORE
  • Part number: T-37-2 (Red)
  • Frequency Range: 1 to 30 MHz
  • u: 10
  • AL: 40 uH/100 turns

Measured on NanoVNA

  • 7 MHz LP filter
  • Built with junk box low voltage ceramic disc caps

LowPass7MHz NanoVNA.png

Rebuild - Higher Power

Toroid 1.24uH 15T.PNG

Toroid 1.41uH 16T.PNG

Simulation

CWAZ LowPass7MHz SPICE IntegerTurnsInd.png

Measured with NanoVNA

  • Excellent performance!!!
  • 7 MHz
    • S21 = -1.55 dB
    • VSWR = 1.008
  • 14 MHz - 1st harmonic
    • S21 = -55.8 dB
    • VSWR = 5.181
  • 21 MHz - 2nd harmonic
    • S21 = -69 dB
    • VSWR = 15.225

CWAZ 7MHZ NANOVNA 125W PLOTS.PNG

CWAZ 7MHZ NANOVNA 125W DATA.PNG

CWAZ - 20M, 14MHz LP Filter

CWAZ-20M-SPICE.PNG

Ceramic Disc Caps

  • High voltage quality caps
    • Ceramic - should these be silver mica caps?
    • Ceramic caps are 10x cheaper than silver mica caps
      • 100pF, Silver Mica cap, P/N: CDV16FF101JO3F, $1.40 (per, qty 10)
      • 100pF, Ceramic cap, P/N: CC45SL3AD101JYNNA, $0.14 (per, qty 10)
    • Will the ceramic caps cause Microphonics or is that only an issue in gain stages?
      • SL caps are single layer
Capacitance (pF) Mfr. # Manufacturer Description
10 S100K33SL0R63K7R Vishay Ceramic Disc Capacitors 10pF 3000V 10% SL0 7.5mm LS
33 CC45SL3AD330JYNNA TDK Ceramic Disc Capacitors D: 5.5mm 1kV 33pF SL 5% LS:5mm
47 CC45SL3AD470JYVNA TDK Ceramic Disc Capacitors D: 5.5mm 1kV 47pF SL 5% LS:5mm
82 CC45SL3AD820JYNNA TDK Ceramic Disc Capacitors D: 6mm 1kV 82pF SL 5% LS:5mm
100 CC45SL3AD101JYNNA TDK Ceramic Disc Capacitors D: 6.5mm 1kV 100pF SL 5% LS:5mm
120 CC45SL3AD121JYNNA TDK Ceramic Disc Capacitors D: 7mm 1kV 120pF SL 5% LS:5mm
200 S201K33S3NN63L6R Vishay Ceramic Disc Capacitors 200PF 1KV 10%
270 CC45SL3AD271JYVNA TDK Ceramic Disc Capacitors D: 9mm 1kV 270pF SL 5% LS:5mm
330 S331K33Y5PR63K7R Vishay Ceramic Disc Capacitors 330pF 3000V 10% Y5P 7.5mm LS
390 CC45SL3AD391JYVNA TDK Ceramic Disc Capacitors D: 10.5mm 1kV 390pF SL 5% LS:5mm
470 D471K20Y5PH6UJ5R Vishay Ceramic Disc Capacitors 470pF 100V 10%
680 S681K29Y5PN63J5R Vishay Ceramic Disc Capacitors 680pF 1000V 10% Y5P 5.0mm LS