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
  - Approx. 1 dBm
9 MHz IF feeds Crystal Filter
- SSB or CW Crystal Filter Design
  - SSB4 Crystal filter
  - CW5 Crystal Filter

Si5351A Drive Level

Two Si5351 Designs
- VFO-001
  - Uses the Si5351 without external driver
- Set drive levels to 2mA, 4mA, 6mA or 8mA
- VFO-003 - Adds 50 Ohm driver
  - Level is fixed
  - Three 74AC14 parts with 150 ohms outputs paralleled

VFO-001 drive

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
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
Needs a 13 dB attenuator

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
3 dB attenuator to reduce for Level 7 mixers (like the ADE-1 mixer)

Kits and Parts ADE-1 Mixer

Kits and Parts Mixer
Not necessary to build and tune diplexer first using NanoVNA and/or tinySA
- Only 1 cap adjust
- Inductors can be spread/compressed

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

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

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

Mixer as Product Detector

RF is 9 MHz from IF stage
LO is 9 MHz BFO
- Minor adjustments to get to side of the base band offset
IF output is audio
- Mixer goes down to DC
- IF needs Audio Filter
- 1.5 mH inductor
- 0.33 uF cap
LTSpice Simulation

Circuit Mods

IF section

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.