Kits and Parts Mixers

Kits and Parts Mixers Features in Common

• All Ports are 50Ω
• +7dBm Local Oscillator Injection Design
• Full Diplexer at the IF Port
• Optional Attenuators for RF & LO Ports
• Available as bare PCB or kit of parts

My Typical Applications

• 7 MHz RF, 40 M band
• 16 MHz LO
  • Si5351A square wave drive, 50 Ohm source impedance, 1.65V peak
• 9 MHz IF feeds Crystal Filter
  • SSB or CW Crystal Filter Design
    • SSB4 Crystal filter
    • CW5 Crystal Filter

Kits and Parts ADE-1 Mixer

• Kits and Parts Mixer
• Not necessary to build and tune diplexer first using NanoVNA and/or tinySA

Toroid Winding Direction

• Toroids needs to be wound to match the pad locations/offsets on the PCB

ADE-1 Schematic

Performance

Port VWSR

• Measured VSWR of 2.23 at 9 MHz with NanoVNA matches spec nicely

ADE-1 Measurements

NanoVNA Measurements

• No RF in
• LO driven by NanoVNA Tx
  • About -10dBm output
• IF output to NanoVNA Rx
• IF at 9 MHz
  • VSWR: 2.233
  • S21 Gain: -67 dB

• NanoVNA
• No LO in
• RF driven by NanoVNA Tx
• IF output to NanoVNA Rx
• IF at 9 MHz
  • VSWR: 2.216
  • S21 Gain: -42 dB

• Scanning from 1 to 100 MHz

tinySA Measurements

LO to IF port isolation

• Driven by VFO-001 3.3V squarewave output
  • Signal level about 0.5 dBm
  • CLK0 = 9 MHz into LO port
• Monitor IF output from mixer on tinySA
  • Output through 20 dB attenuator (tinySA set to -20dB gain)

Mixer Operation

• Driven by VFO-001 3.3V squarewave outputs
  • Signal level about 0.5 dBm
  • CLK0 = RF @7 MHz VFO-001 output with 30 dB attenuator
  • CLK1 = LO @16 MHz no attenuator
• Monitor IF output from mixer on tinySA
  • IF out to tinySA with 20 dB attenuator (tinySA set to -20dB gain)

• Same but 9 MHz picked out
• Approx. 8 dB insertion loss

• Look at 7 MHz RF freq on IF output

• Look at 16 MHz LO freq on IF output

Bridged Tee Diplexer

Diplexor is a bandpass/band-stop filter popularized by Joe Reisert W1JR that is used after a double Balanced Mixer to provide a 50 ohm termination to all frequencies at the mixer's IF port, and to the following amplifier stage. Maintaining a consistent load at the mixer avoids overload and Inter-Modulation Distortion (IMD) effects that these mixers are prone to when not properly terminated.

LTSpice simulation

• 9 MHz
• FT37-67, 20T-12" = 8 uH
• T37-17, 13T-10" = 250 nH
• C2 adjusts peak from left to right

• Diplexer Calculator (Bridged Tee) Diplexer Calculator
• Mixer Diplexer description

Adjust Diplexer C1 (ADE-1)

• Drive RF port from NanoVNA
• Listen on IF port of NanoVNA
• No drive on LO
• 9 MHz is IF design frequency
• Nano VNA set to scan from 1 Mhz to 30 MHz
  • Shows peak at 9 MHz

• Scan from 8 to 10 MHz
• Adjust C1 to peak near 9 MHz
  • Eliminate double peaks

Kits and Parts Diode Mixer

• Double Balanced Diode Ring Mixer Kit
• Build and tune diplexer first