Difference between pages "Kits and Parts Mixers" and "QRP Labs High Performance SDR Receiver"

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[[file:K&P_ADE_Mixer-P1899-720px.jpg]]
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[[file:QRP-Labs_P1956-720px.jpg]]
  
== Kits and Parts Mixers - Features in Common ==
+
== Features ==
  
* Available as [https://kitsandparts.com/DBDM.php Diode Ring Mixer] or [https://kitsandparts.com/ADE.php ADE-1 || ADE-6 Double Balanced Diode Ring Mixer] kits from [https://kitsandparts.com/ Kits and Parts]
+
* Three modules
* LO, IF, RF Ports are all 50Ω
+
** [http://qrp-labs.com/receiver QRP Labs High Performance Receiver Module]
* +7dBm Local Oscillator injection level
+
*** Direct Conversion Receiver
** As measured into 50Ω load
+
*** Uses a Quadrature Sampling Detector (QSD), also known as a Tayloe Detector
*** Mixers are not linear and loads should not be measured at the mixer
+
*** [https://www.onsemi.com/pdf/datasheet/fst3253-d.pdf FST3253] Mixer is arranged as a double-balanced mixer for maximum performance
* ~5dB RF > IF conversion loss in HF region
+
*** Circuit to mute receiver during transmit
* IF Port
+
*** [https://www.ti.com/lit/ds/symlink/lm4562.pdf Low noise LM4562 op-amps] are used in instrumentation amplifier configuration to provide excellent common mode noise rejection
** Full Diplexer at the IF Port
+
*** The audio output of the module is isolated using two 600:600-ohm transformers to reduce or eliminate the ground loop problems which can easily occur in SDR systems
** Low Pass Filter can be populated if used as Product Detector / Balanced Modulator
+
*** The module is designed to directly drive a stereo input sound-card or with a polyphase filter card
* Board has pads (1206 SMT or 1/8W resistor pads) for optional Attenuators on RF & LO Ports
+
*** Receiver board has a socket for the standard QRP Labs Band Pass Filter kit which can be routed to an external bandpass filter switch card
* 3 pin, 0.1" pads at board edges allow SMA edge connectors to be used
+
*** The receiver requires a local oscillator (LO) input at 4x the receive frequency
* Mounting holes in all 4 corners
+
*** [http://qrp-labs.com/images/receiver/receiver2.pdf Receiver Build instructions]
 +
** [[RF Band Pass Filters|QRP Labs Band Pass Filter]]
 +
*** Can be used with a [https://qrp-labs.com/ultimatelpf.html Switched Bandpass filter board] for multiband operation
 +
*** [http://qrp-labs.com/bpfkit.html 10/15/20/40/80M QRP Labs Band Pass Filter Kits]
 +
*** [https://qrp-labs.com/images/bpfkit/bpf2.pdf Band Pass Filter Build instructions]
 +
** [https://qrp-labs.com/polyphase QRP Labs Polyphase filter]
 +
*** Polyphase network plug-in module kit cancels the unwanted sideband and produces a single sideband (SSB) output
 +
*** [http://qrp-labs.com/images/polyphase/polyphase2a.pdf Polyphase Filter Build instructions]
 +
* Band Pass Filter and Polyphase filter mount on Receiver Module
 +
* Current draw - measured total 70 mA (5V regulator
 +
* The receiver module is sized 80 x 37mm
  
== Kits and Parts ADE-1 Mixer ==
+
=== Build / Assembly ===
  
* [https://kitsandparts.com/ADE.php Kits and Parts Mixer]
+
* Power supply + 12V in
* Mini-Circuits ADE-1+ Double Balanced Diode Mixer with built in 50Ω transformers
+
** Distribute 12V using [[TinyGrid85]] card with caps
** [https://www.minicircuits.com/pdfs/ADE-1+.pdf ADE-1+ Datasheet]
+
** Needs 5V supply
* Not necessary to build and tune diplexer first if using [[NanoVNA]] and/or [[tinySA]]
+
*** Partly populated [[TinyGrid85]] card with caps and 5V regulator (no ATTiny85 chip)
** Only 1 cap adjust
+
** Opamps can be powered from 5V or 12-14V (for higher dynamic range)
** Inductors can also be spread/compressed if needed
+
* [[AudioAmp386|Audio Amplifier]]
* Available from [https://kitsandparts.com/ADE.php Kits and Parts] as bare PCB or kit of parts
+
* The receiver requires a local oscillator (LO) input at 4x the receive frequency
* Bare board - $5
+
** Using [[VFO-003]] with [https://github.com/land-boards/lb-Arduino-Code/tree/master/LBCards/VFO-003_4X 4x output software option]
* Kit - $14
+
** [https://github.com/etherkit/Si5351Arduino/tree/master/src Si5351 Driver]
** Good deal since the [https://www.mouser.com/ProductDetail/Mini-Circuits/ADE-1%2b?qs=xZ%2FP%252Ba9zWqZNkkNe3uAsRQ%3D%3D mixer itself is $6]
 
  
[[file:ADE-1.SCH.png]]
+
== Silkscreen / Pinout ==
  
[[file:ADE-1.PCB.png]]
+
[[file:IQ_RX_PCB.PNG]]
  
=== ADE-1 Schematic ===
+
=== Pins ===
  
[[file:ADE-1_Schematic.PNG]]
+
* IQ pins
 +
* I, GND, Q outputs
 +
* Power pins
 +
* GND, +5V, +5V or +12V to +14V
 +
* Tx Mute Input
 +
** 5V mutes inputs
 +
* LO input
 +
** 3.3V from Si5351A oscillators
 +
* IF input
 +
** From external Bandpass Filter Switch
  
=== Performance ===
+
== Receiver Module ==
  
[[file:Chart_dBm-to-Volts.PNG]]
+
[[file:QRP-Labs_Receiver-Base_P1969-720px.jpg]]
  
[[file:ADE-1_Performance.PNG]]
+
== Polyphase Module ==
  
[[file:ADE-1_ElectricalSpecs.PNG]]
+
*  Important to observe part outlines
 +
** Adjacent resistors can be put in "sideways"
  
=== Port VWSR ===
+
[[file:QRP-Labs_Polyphase-Filter_P1966-500px.jpg]] [[file:Polyphase-pcb.PNG]]
  
* Measured VSWR of 2.23 at 9 MHz with NanoVNA matches spec nicely
+
[[file:Polyphase-pcb-2.png]]
  
[[file:ADE-1_LO_VSWR.PNG]]
+
[[file:Polyphase-Schematic.PNG]]
  
[[file:ADE-1_IF_VSWR.PNG]]
+
* USB/LSB select jumpers
 +
** Set to USB in the above picture
  
[[file:ADE-1_RF_VSWR.PNG]]
+
[[file:Polyphase_LSB-USB-Jumpers.PNG]]
  
=== ADE-1 Measurements ===
+
== Bandpass Module ==
  
==== NanoVNA Measurements ====
+
* 20M - 14 MHz Filter
  
* No RF in
+
[[file:QRP-Labs_BandPass-Filter_P1963-720px.jpg]]
* LO driven by NanoVNA Tx
 
** About -10dBm output
 
* IF output to NanoVNA Rx
 
* IF at 9 MHz
 
** VSWR: 2.233
 
** S21 Gain: -67 dB
 
  
[[file:ADE-1.NanoVNA_LO-to-IF.png]]
+
[[file:Bandpass_Filter_Schematic.PNG]]
  
 
* NanoVNA
 
* NanoVNA
* No LO in
+
** 12-16 MHz
* RF driven by NanoVNA Tx
 
* IF output to NanoVNA Rx
 
* IF at 9 MHz
 
** VSWR: 2.216
 
** S21 Gain: -42 dB
 
  
[[file:ADE-1.NanoVNA_RF-to-IF.png]]
+
[[FILE:14MHz_12-16MHz_Band_Pass_Filter-2.png]]
  
* Scanning from 1 to 100 MHz
+
* Data
  
[[file:ADE-1.NanoVNA_RF-to-IF_1-100MHz.png]]
+
[[FILE:14MHz_12-16MHz_Band_Pass_Filter-Data.png]]
  
==== tinySA Measurements ====
+
[[FILE:  14MHz_12-16MHz_Band_Pass_Filter-Analysis.png]]
  
===== LO to IF port isolation =====
+
== Build Issues ==
  
* Driven by [[VFO-001]] 3.3V squarewave output
+
* Transformers don't fit well and crowd parts around them
** Signal level about 0.5 dBm
+
* QRP Labs polyphase module pics are for older revision card
** CLK0 = 9 MHz into LO port
+
* One of the two variable caps on the Bandpass filter was very hard to turn even after the first turn
* Monitor IF output from mixer on tinySA
 
** Output through 20 dB attenuator (tinySA set to -20dB gain)
 
  
[[file:ADE-1.tinySA_RF-to-IF_9Mhz-center.png]]
+
== Reference Documents ==
  
===== Mixer Operation =====
+
* [https://wparc.us/presentations/SDR-2-19-2013/Tayloe_mixer_x3a.pdf Ultra Low Noise, High Performance, Zero IF Quadrature Product Detector and Preamplifier]
 
+
* [http://antennoloog.nl/data/documents/Understanding_and_designing_Polyphase_networks_V4.0.pdf Understanding and Designing Sequence Asymmetric Polyphase Networks]
* Mixer is driven by [[VFO-001]] 3.3V squarewave outputs
+
* [https://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1991/12/page29/ The double-tuned Circuit: An experimenter's tutorial]
** Signal output levels about 0.5 dBm
+
* [http://hanssummers.com/polyphase 40/80m CW/SSB receiver]
** CLK0 = RF @7 MHz [[VFO-001]] output with 30 dB attenuator
+
* [http://hanssummers.com/images/stories/polyphase/polyphase.pdf Experimental Polyphase Receiver]
** CLK1 = LO @16 MHz no attenuator
+
* [http://www.arrl.org/files/file/Technology/tis/info/pdf/030304qex020.pdf A Software Defined Radio for the Masses]
* Monitor IF output from mixer on [[tinySA]]
+
* [http://norcalqrp.org/files/AustinNC2030Presentation.pdf Very High Performance Image Rejecting Direct Conversion Receivers] - NC2030 Radio
** IF out to tinySA with 20 dB attenuator (tinySA set to -20dB gain)
 
 
 
[[file:ADE-1.tinySA_LO-16MHz_RF-7MHz-to-IF_9Mhz-center.png]]
 
 
 
* Same but 9 MHz picked out
 
* Approx. 8 dB insertion loss
 
 
 
[[file:ADE-1.tinySA_LO-16MHz_RF-7MHz-to-IF_9Mhz-at9MHz.png]]
 
 
 
* Look at 7 MHz RF freq on IF output
 
 
 
[[file:ADE-1.tinySA_LO-16MHz_RF-7MHz-to-IF_9Mhz-at7MHz.png]]
 
 
 
* Look at 16 MHz LO freq on IF output
 
 
 
[[file:ADE-1.tinySA_LO-16MHz_RF-7MHz-to-IF_9Mhz-at16MHz.png]]
 
 
 
== Kits and Parts Diode Mixer ==
 
 
 
* [https://kitsandparts.com/DBDM.php Double Balanced Diode Ring Mixer Kit]
 
* Not necessary to build and tune diplexer first is using a [[NanoVNA]] or [[tinySA]] to adjust
 
* Available from [https://kitsandparts.com/ADE.php Kits and Parts] as bare PCB or kit of parts
 
* Bare board - $5
 
* Kit - $12
 
 
 
[[file:DBDM.SCH.png]]
 
 
 
[[file:DBDM.PCB.png]]
 
 
 
== 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|Crystal Filter Design]] - 9 MHz nominal
 
*** [[Crystal Filter Design#SSB 4 Crystal Filter on Kits and Parts Board|SSB4 Crystal filter]]
 
*** [[SSB6_Design|SSB6 Design Crystal filter]]
 
*** [[Crystal_Filter_Design#CW 5 Crystal Filter on Kits and Parts Board|CW5 Crystal Filter]]
 
* Use Si5351 to drive LO and/or RF ports
 
 
 
=== Si5351A Drive Level ===
 
 
 
* [https://www.skyworksinc.com/-/media/Skyworks/SL/documents/public/data-sheets/Si5351-B.pdf 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:
 
 
 
[[file:RMS-SquareWave.PNG]]
 
 
 
* [https://www.redcrab-software.com/en/Calculator/Electrics/Rectangular-Voltage-RMS-Value#:~:text=The%20rms%20value%20is%20for%20square-wave%20voltages%20whose,rms%20value%20is%20equal%20to%20the%20peak%20value Square Wave Calculator]
 
 
 
[[file:RMS-SquareWave-2.PNG]]
 
 
 
* Drive level of 3.3V
 
 
 
[[file:RMS-SquareWave-3.PNG]]
 
 
 
* 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|VFO-003 Output_Power - Power Calculation]]
 
 
 
* RMS Voltage of square wave
 
 
 
[[file:SquareWace-3.3V.PNG]]
 
 
 
* [https://www.redcrab-software.com/en/Calculator/Electrics/Rectangular-Voltage-RMS-Value Square Wave Calculator]
 
* 2.33V^2/100 = 0.0542W
 
* Power is split between Source and load resistors
 
* 0.02714W
 
 
 
* dBm Calculation
 
 
 
* [https://www.rapidtables.com/convert/power/dbm-converter.html mW to dBm calculator]
 
 
 
[[file:SquareWave-3.3V_dBm.PNG]]
 
 
 
* 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 [[W7ZOI_Filters_on_Kits_and_Parts_Boards#SSB_4_Crystal_Filter_on_Kits_and_Parts_Board|SSB4 Crystal filter]]
 
* IF output from mixer to [[W7ZOI_Filters_on_Kits_and_Parts_Boards#SSB_4_Crystal_Filter_on_Kits_and_Parts_Board|SSB4 Crystal filter]] input
 
* Monitor [[W7ZOI_Filters_on_Kits_and_Parts_Boards#SSB_4_Crystal_Filter_on_Kits_and_Parts_Board|SSB4 Crystal filter]] output on [[tinySA]]
 
** No attenuator on IF output into tinySA
 
 
 
[[file:tinySA_ADE-1-MixerwCystalFilter_9MHz_center.png]]
 
 
 
* Scan from 1 to 30 MHz
 
* Note other signals are now well into the noise floor of the [[tinySA]]
 
** LO present but down
 
 
 
[[file:tinySA_ADE-1-MixerwCystalFilter_1_to_30MHz.png]]
 
 
 
* 16 MHz LO level
 
* 16 dB lower with crystal filter
 
 
 
[[file:tinySA_ADE-1-MixerwCystalFilter_16MHz_LO-Suppression.png]]
 
 
 
===== 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 [[W7ZOI_Filters_on_Kits_and_Parts_Boards#CW_5_Crystal_Filter_on_Kits_and_Parts_Board|CW5 Crystal filter]]
 
* IF output from mixer to [[W7ZOI_Filters_on_Kits_and_Parts_Boards#C_W5_Crystal_Filter_on_Kits_and_Parts_Board|CW5 Crystal filter]] input
 
* Monitor [[W7ZOI_Filters_on_Kits_and_Parts_Boards#CW_5_Crystal_Filter_on_Kits_and_Parts_Board|CW5 Crystal filter]] output on [[tinySA]]
 
** No attenuator on IF output into tinySA
 
 
 
[[file:tinySA_ADE-1-Mixerw_CW5CystalFilter_9MHz_center.png]]
 
 
 
* Scan from 1 to 30 MHz
 
* Note other signals are now well into the noise floor of the [[tinySA]]
 
** LO present but down
 
 
 
[[file:tinySA_ADE-1-Mixerw_CW5CystalFilter_9MHz_1to30MHz.png]]
 
 
 
* 16 MHz LO level
 
* 16 dB lower with crystal filter
 
 
 
[[file:tinySA_ADE-1-MixerwCW5CystalFilter_16MHz_LO-Suppression.png]]
 
 
 
===== 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 [[W7ZOI_Filters_on_Kits_and_Parts_Boards#CW3_Crystal_Filter_on_Kits_and_Parts_Board|CW3 Crystal filter]]
 
* IF output from mixer to [[W7ZOI_Filters_on_Kits_and_Parts_Boards#CW3_Crystal_Filter_on_Kits_and_Parts_Board|CW3 Crystal filter]] input
 
* Monitor [[W7ZOI_Filters_on_Kits_and_Parts_Boards#CW3_Crystal_Filter_on_Kits_and_Parts_Board|CW3 Crystal filter]] output on [[tinySA]]
 
** No attenuator on IF output into tinySA
 
 
 
[[file:tinySA_ADE-1-Mixerw_CW3CystalFilter_9MHz_center.png]]
 
 
 
* Scan from 1 to 30 MHz
 
* Note other signals are now well into the noise floor of the [[tinySA]]
 
** LO present but down
 
 
 
[[file:tinySA_ADE-1-Mixerw_CW3CystalFilter_9MHz_1to30MHz.png]]
 
 
 
* 16 MHz LO level
 
* 16 dB lower with crystal filter
 
 
 
[[file:tinySA_ADE-1-MixerwCW3CystalFilter_16MHz_LO-Suppression.png]]
 
 
 
== Bridged Tee Diplexer ==
 
 
 
Diplexor is a bandpass/band-stop filter popularized by [https://www.youtube.com/watch?v=iVUv8C-8g-Y 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
 
 
 
[[FILE:DIPLEXER_SPICE_SIM.PNG]]
 
 
 
* [https://www.changpuak.ch/electronics/calc_16a.php Diplexer Calculator (Bridged Tee) Diplexer Calculator]
 
* [https://www.qsl.net/g3oou/mixerterminations.html Mixer Diplexer description]
 
 
 
[[file:Diplexer.PNG]]
 
 
 
[[file:Diplexer_pass.PNG]]
 
 
 
<video type="youtube">zOk_0IiIgZY</video>
 
 
 
==== Toroid Winding Direction ====
 
 
 
* Toroids needs to be wound to match the pad locations/offsets on the PCB
 
 
 
[[file:toroid-cw.jpg]]
 
 
 
=== 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
 
 
 
[[file:ADE-1.NanoVNA_RF-to-IF.png]]
 
 
 
* Scan from 8 to 10 MHz
 
* Adjust C1 to peak near 9 MHz
 
** Eliminate double peaks
 
 
 
[[file:ADE-1.NanoVNA_RF-to-IF_8-10MHz.png]]
 
 
 
== ADE-1 Mixer as Product Detector ==
 
 
 
[[FILE:P1927-720PX.jpg]]
 
 
 
* 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
 
** [https://www.mouser.com/ProductDetail/871-B78108S1155J 1.5 mH inductor] in series as filter on audio output
 
* LTSpice Simulation
 
 
 
[[file:LP_Audio-2.PNG]]
 
 
 
* Circuit Mods
 
 
 
[[file:ADE-1_AF_Filter-2.PNG]]
 
 
 
* IF section
 
 
 
[[file:ADE-1_AF_Filter_Physicals-4.PNG]]
 
 
 
== Videos ==
 
 
 
<video type="youtube">GvadQpkZ8l0</video>
 
 
 
<video type="youtube">Mm7WfVzr1ao</video>
 
 
 
<video type="youtube">7qhY_NMNzxw</video>
 

Revision as of 00:02, 22 November 2021

QRP-Labs P1956-720px.jpg

Features

Build / Assembly

Silkscreen / Pinout

IQ RX PCB.PNG

Pins

  • IQ pins
  • I, GND, Q outputs
  • Power pins
  • GND, +5V, +5V or +12V to +14V
  • Tx Mute Input
    • 5V mutes inputs
  • LO input
    • 3.3V from Si5351A oscillators
  • IF input
    • From external Bandpass Filter Switch

Receiver Module

QRP-Labs Receiver-Base P1969-720px.jpg

Polyphase Module

  • Important to observe part outlines
    • Adjacent resistors can be put in "sideways"

QRP-Labs Polyphase-Filter P1966-500px.jpg Polyphase-pcb.PNG

Polyphase-pcb-2.png

Polyphase-Schematic.PNG

  • USB/LSB select jumpers
    • Set to USB in the above picture

Polyphase LSB-USB-Jumpers.PNG

Bandpass Module

  • 20M - 14 MHz Filter

QRP-Labs BandPass-Filter P1963-720px.jpg

Bandpass Filter Schematic.PNG

  • NanoVNA
    • 12-16 MHz

14MHz 12-16MHz Band Pass Filter-2.png

  • Data

14MHz 12-16MHz Band Pass Filter-Data.png

14MHz 12-16MHz Band Pass Filter-Analysis.png

Build Issues

  • Transformers don't fit well and crowd parts around them
  • QRP Labs polyphase module pics are for older revision card
  • One of the two variable caps on the Bandpass filter was very hard to turn even after the first turn

Reference Documents