Kits and Parts Mixers

Kits and Parts Mixers - Features in Common

• Available as Diode Ring Mixer or ADE-1 || ADE-6 Double Balanced Diode Ring Mixer kits from Kits and Parts
• LO, IF, RF Ports are all 50Ω
• +7dBm Local Oscillator injection level
  • As measured into 50Ω load
    • Mixers are not linear and loads should not be measured at the mixer
• ~5dB RF > IF conversion loss in HF region
• IF Port
  • Full Diplexer at the IF Port
  • Low Pass Filter can be populated if used as Product Detector / Balanced Modulator
• Board has pads (1206 SMT or 1/8W resistor pads) for optional Attenuators on RF & LO Ports
• 3 pin, 0.1" pads at board edges allow SMA edge connectors to be used
• Mounting holes in all 4 corners

Kits and Parts ADE-1 Mixer

• Kits and Parts Mixer
• Mini-Circuits ADE-1+ Double Balanced Diode Mixer with built in 50Ω transformers
  • ADE-1+ Datasheet
• Not necessary to build and tune diplexer first if using NanoVNA and/or tinySA
  • Only 1 cap adjust
  • Inductors can also be spread/compressed if needed
• Available from Kits and Parts as bare PCB or kit of parts
  • Bare board - $5
  • Kit - $14
    • Good deal since the mixer itself is $6

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

• Mixer is driven by VFO-001 3.3V squarewave outputs
  • Signal output levels 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

Kits and Parts Diode Mixer

• Double Balanced Diode Ring Mixer Kit
• Not necessary to build and tune diplexer first is using a NanoVNA or tinySA to adjust
• Available from Kits and Parts as bare PCB or kit of parts
  • Bare board - $5
  • Kit - $12

Diode Mixer Card Schematic

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

Toroid Winding Direction

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

Adjust IF Diplexer C1 (ADE-1)

• Drive RF port from NanoVNA
  • Nominal 0 dBm drive level
• IF port is output
  • Listen on IF port on NanoVNA
• No drive on LO
• 9 MHz is IF design frequency
• Nano VNA set to scan from 1 Mhz to 30 MHz
  • Shows peak expected signal around 9 MHz

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

ADE-1 Mixer as Product Detector

• RF is 9 MHz from IF stage
• LO is 9 MHz BFO from VFO-003
  • Minor adjustments to get to side of the base band offset
• IF output is audio
  • Mixer goes down to DC
• IF needs Audio Filter
  • IF port wants to see 50 Ohm termination across output
  • 0.33 uF cap/50 ohms terminates higher frequencies at 50 ohms
  • 1.5 mH inductor in series as filter on audio output
• LTSpice Simulation

• Circuit Mods

• IF section

Typical Application

• 7 MHz RF, 40 M band
• 16 MHz LO
  • Si5351A square wave drive
• 9 MHz (difference 16-7=9) IF feeds Crystal Filter
  • SSB or CW Crystal Filter Design - 9 MHz nominal
    • SSB4 Crystal filter
    • SSB6 Design Crystal filter
    • CW5 Crystal Filter
• Use Si5351 to drive LO port
  • Drive pad attenuator may be required
• Use Si5351 to drive RF port for testing
  • Use large external pad attenuator for low level signal insertion

Si5351A Drive Level

• Si5351A used to drive LO and/or RF ports
  • 3 outputs
  • LO at full level (+7dBm)
  • RF at various levels with attenuators to drop to expected RF signal levels
• Don't want more than 7 dBm into LO or RF ports
• Two Si5351 Designs to drive ADE-1 LO or RF ports
  • VFO-001
    • Uses the Si5351 without external drivers
    • Set drive levels to 2mA, 4mA, 6mA or 8mA
  • VFO-003 - Adds 50Ω drivers
    • Level is fixed
    • Three 74AC14 parts with 150 ohms outputs paralleled
    • 13 dBm output
    • Install 6 dBm attenuator on board (13-6=7)

VFO-001 drive

• The RMS value is for square-wave voltages whose pulse duration (ti) and pause (tp) have the same length:

• Square Wave Calculator

• Drive level of 3.3V

• 100 mW is 20 dBm
• ADE-1 needs 7 dBm level
• Would need a 13 dB attenuator
  • Not actually true
    • Although the Si5351 datasheet says it drives 50 Ohms loads this is not exactly the case
    • Drive levels are controlled by the output current setting
• Si5351A outputs measured on VFO-001
  • Drive Level 2 mA = 0.2 dBm
  • Drive Level 4 mA = 6.2 dBm << Use this level
  • Drive Level 6 mA = 9.7 dBm
  • Drive Level 8 mA = 11.7 dBm

VFO-003 drive

• VFO-003 Output_Power - Power Calculation

• RMS Voltage of square wave

• Square Wave Calculator
• 2.33V^2/100 = 0.0542W
• Power is split between Source and load resistors
• 0.02714W

• dBm Calculation

• mW to dBm calculator

• Expect 14.3 dBm drive
• Measured 12.6 dBm with NanoVNA - Pretty close
• Need a 6 dB attenuator on the LO input to reduce VFO-003 for Level 7 mixers (like the ADE-1 mixer)
  • 6 dB 150-36-150

Mixer with SSB4 IF Crystal Filter

• Mixer is driven by VFO-001 3.3V squarewave outputs
  • Signal output levels about 0.5 dBm
  • CLK0 = RF @7 MHz VFO-001 output with 20 dB attenuator
  • CLK1 = LO @15.998,6 MHz no attenuator
    • Adjusted to center of the SSB4 Crystal filter
• IF output from mixer to SSB4 Crystal filter input
• Monitor SSB4 Crystal filter output on tinySA
  • No attenuator on IF output into tinySA

• Scan from 1 to 30 MHz
• Note other signals are now well into the noise floor of the tinySA
  • LO present but down

• 16 MHz LO level
• 16 dB lower with crystal filter

Mixer with CW5 IF Crystal Filter

• Mixer is driven by VFO-001 3.3V squarewave outputs
  • Signal output levels about 0.5 dBm
  • CLK0 = RF @7 MHz VFO-001 output with 20 dB attenuator
  • CLK1 = LO @15.997,9 MHz no attenuator
    • Adjusted to center of the CW5 Crystal filter
• IF output from mixer to CW5 Crystal filter input
• Monitor CW5 Crystal filter output on tinySA
  • No attenuator on IF output into tinySA

• Scan from 1 to 30 MHz
• Note other signals are now well into the noise floor of the tinySA
  • LO present but down

• 16 MHz LO level
• 16 dB lower with crystal filter

Mixer with CW3 IF Crystal Filter

• Mixer is driven by VFO-001 3.3V squarewave outputs
  • Signal output levels about 0.5 dBm
  • CLK0 = RF @7 MHz VFO-001 output with 20 dB attenuator
  • CLK1 = LO @15.997,7 MHz no attenuator
    • Adjusted to center of the CW3 Crystal filter
• IF output from mixer to CW3 Crystal filter input
• Monitor CW3 Crystal filter output on tinySA
  • No attenuator on IF output into tinySA

• Scan from 1 to 30 MHz
• Note other signals are now well into the noise floor of the tinySA
  • LO present but down

• 16 MHz LO level
• 16 dB lower with crystal filter