Difference between pages "RF Attenuators" and "QRP Labs High Performance SDR Receiver"

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== Purchased Attenuators ==
+
[[file:QRP-Labs_P1956-720px.jpg]]
  
=== Programmable Attenuator ===
+
== Features ==
  
* [[PE4302 RF Attenuator|PE4302 RF Attenuator board in my enclosure design]]
+
* Three modules
 +
** [http://qrp-labs.com/receiver QRP Labs High Performance Receiver Module]
 +
*** Direct Conversion Receiver
 +
*** Uses a Quadrature Sampling Detector (QSD), also known as a Tayloe Detector
 +
*** [https://www.onsemi.com/pdf/datasheet/fst3253-d.pdf FST3253] Mixer is arranged as a double-balanced mixer for maximum performance
 +
*** Circuit to mute receiver during transmit
 +
*** [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
 +
*** 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
 +
*** The module is designed to directly drive a stereo input sound-card or with a polyphase filter card
 +
*** 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
 +
*** The receiver requires a local oscillator (LO) input at 4x the receive frequency
 +
*** [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
  
[[file:PE4302_P1833-720px.jpg]]
+
=== Build / Assembly ===
  
=== Triple Attenuator ===
+
* Power supply + 12V in
 +
** Distribute 12V using [[TinyGrid85]] card with caps
 +
** Needs 5V supply
 +
*** Partly populated [[TinyGrid85]] card with caps and 5V regulator (no ATTiny85 chip)
 +
** Opamps can be powered from 5V or 12-14V (for higher dynamic range)
 +
* [[AudioAmp386|Audio Amplifier]]
 +
* The receiver requires a local oscillator (LO) input at 4x the receive frequency
 +
** Using [[VFO-003]] with [https://github.com/land-boards/lb-Arduino-Code/tree/master/LBCards/VFO-003_4X 4x output software option]
 +
** [https://github.com/etherkit/Si5351Arduino/tree/master/src Si5351 Driver]
  
* [[0/10/20/30 dB Attenuator]]
+
== Silkscreen / Pinout ==
  
[[file:ATTEN4_CHINA_PCB.PNG]]
+
[[file:IQ_RX_PCB.PNG]]
  
== Homebrew RF Attenuators ==
+
=== Pins ===
  
[[file:Atten_30dB_20dV_P1812-720px.jpg]]
+
* IQ pins
=== 30 dB Attenuator ===
+
* 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
  
* [http://leleivre.com/rf_pipad.html Pi Attenuator Calculator]
+
== Receiver Module ==
  
[[file:Atten30dB_P116-720px.jpg]]
+
[[file:QRP-Labs_Receiver-Base_P1969-720px.jpg]]
  
[[file:30dB_Attenuator.PNG]]
+
== Polyphase Module ==
  
* Built
+
* Important to observe part outlines
** Standard 5% resistor values
+
** Adjacent resistors can be put in "sideways"
** R1 = 820 in parallel with 22K = 790.6 ohms
 
** R2 = 2 paralleled 120 Ohm 1/4W resistors paralleled with 470 ohms = 53.2 ohms
 
** Flat from 0-30 MHz
 
** Measured attenuation is flat
 
*** -30.01dB at 1 MHz
 
*** -30.24dB at 30 MHz
 
** Input Impedance - 53.1 ohms, 21.3nF
 
** SWR 1.06
 
** 1/2W max (5VDC max, 0 ohm source)
 
  
* NanoVNA scan data
+
[[file:QRP-Labs_Polyphase-Filter_P1966-500px.jpg]] [[file:Polyphase-pcb.PNG]]
  
[[file:30dB_Attenuator_NanoVNA_Setup_Curve_900MHz.PNG]]
+
[[file:Polyphase-pcb-2.png]]
  
[[file:30dB_Attenuator_NanoVNA_Data_900MHz.PNG]]
+
[[file:Polyphase-Schematic.PNG]]
  
* LTSPICE Simulation
+
* USB/LSB select jumpers
 +
** Set to USB in the above picture
  
[[file:LTSPice_30dB.PNG]]
+
[[file:Polyphase_LSB-USB-Jumpers.PNG]]
  
=== 20 dB Attenuator ===
+
== Bandpass Module ==
  
[[file:Atten_20dB_P115-720px.jpg]]
+
* 20M - 14 MHz Filter
  
[[file:20dB_Attenuator.PNG]]
+
[[file:QRP-Labs_BandPass-Filter_P1963-720px.jpg]]
  
* Build
+
[[file:Bandpass_Filter_Schematic.PNG]]
** Standard 5% resistor values
 
** R1 = 2 of 510 in parallel also in parallel with 8.2K = 247.3 ohms
 
** R2 = 2 paralleled 150 Ohm 1/2W resistors paralleled with 330 ohms = 61.11 ohms
 
** Flat from 0-30 MHz
 
** Measured attenuation is flat
 
** Input Impedance - tbd ohms, tbd nF
 
** SWR tbd
 
** 1W max (8.6 V max, 0 ohm source)
 
 
 
[[file:20dB_Attenuator_NanoVNA_Setup_Curve_900MHz.PNG]]
 
 
 
[[file:20dB_Attenuator_NanoVNA_Data_900MHz.PNG]]
 
 
 
* LTSPICE Simulation
 
 
 
[[file:LTSPice_20dB.PNG]]
 
 
 
=== Attenuator Construction ===
 
 
 
* Single side copper clad PCB
 
** Approx 2"x1"
 
* Clean with steel wool
 
* Solder SMA connectors
 
** Use large alligator clips to hold while soldering
 
** Solder on sides only
 
 
 
[[file:Atten_01_SMAs_720px.jpg]]
 
 
 
* Cut "T" Shaped pads
 
** I used nibbler
 
* Center fits between connector ground pins
 
* Glue down pads with Superglue
 
 
 
[[file:Atten_02_Pads_720px.jpg]]
 
 
 
* Solder center pin with big solder blob
 
** A bit too high for direct contact
 
* Verify raised pad does not short to ground
 
 
 
[[file:Atten_03_Solder CenterPads_720px.jpg]]
 
 
 
* Solder side resistor(s)
 
* Leave room for center resistor(s)
 
 
 
[[file:Atten_04_Solder Side_Resistors_720px.jpg]]
 
 
 
* Measure side resistors from pad to ground
 
* Should match value
 
* Solder center resistor(s)
 
 
 
[[file:Atten_05_Solder Center_Resistors_720px.jpg]]
 
 
 
* Verify no shorts between centers and ground
 
 
 
== Attenuator Design - Rev 2 ==
 
 
 
[[FILE:ATTEN.PNG]]
 
 
 
* SMA connectors
 
* Resistors
 
** 1206
 
*** 1/4W
 
** 1% values
 
 
 
[[file:10dB_Attenuator.PNG]]
 
 
 
=== Parts ===
 
 
 
{| class="wikitable"
 
! Mfr. #
 
! Manufacturer
 
! Customer #
 
! Qty
 
! R1/R2
 
! Description
 
|-
 
| RK73H2BTTE17R8F
 
| KOA Speer
 
| ATTEN_03DB
 
| 1
 
| R1
 
| Resistors - SMD 1/4W 17.8 ohms 1%
 
|-
 
| RC1206FR-07294RL
 
| YAGEO
 
| ATTEN_03DB
 
| 2
 
| R2
 
| Resistors - SMD 294 ohms 1/4W 1206 1%
 
|-
 
| RK73H2BTTD37R4F
 
| KOA Speer
 
| ATTEN_06DB
 
| 1
 
| R1
 
| Resistors - SMD 1/4W 37.4 ohms 1%
 
|-
 
| CRCW1206150RFKEAC
 
| Vishay
 
| ATTEN_06DB
 
| 2
 
| R2
 
| Resistors - SMD 1/4Watt 150 ohms 1%
 
|-
 
| RC1206FR-0771R5L
 
| YAGEO
 
| ATTEN_10DB
 
| 1
 
| R1
 
| Resistors - SMD 71.5 ohms 1/4W 1206 1%
 
|-
 
| RC1206FR-0797R6L
 
| YAGEO
 
| ATTEN_10DB
 
| 2
 
| R2
 
| Resistors - SMD 97.6 ohms 1/4W 1206 1%
 
|-
 
| RK73H2BTTD1070F
 
| KOA Speer
 
| ATTEN_13DB
 
| 1
 
| R1
 
| Resistors - SMD 1/4W 107 ohms 1%
 
|-
 
| RC1206FR-0778R7L
 
| YAGEO
 
| ATTEN_13DB
 
| 2
 
| R2
 
| Resistors - SMD 78.7 ohms 1/4W 1206 1%
 
|-
 
| AC1206FR-07249RL
 
| YAGEO
 
| ATTEN_20DB
 
| 1
 
| R1
 
| Resistors - SMD 249 ohms 1/4W 1206 1%
 
|-
 
| RK73H2BTTDD61R9F
 
| KOA Speer
 
| ATTEN_20DB
 
| 2
 
| R2
 
| Resistors - SMD 61.9 ohms 1%
 
|-
 
| RK73H2BTTD7870F
 
| KOA Speer
 
| ATTEN_30DB
 
| 1
 
| R1
 
| Resistors - SMD 1/4W 787 ohms 1%
 
|-
 
| AC1206FR-0753R6L
 
| YAGEO
 
| ATTEN_30DB
 
| 2
 
| R2
 
| Resistors - SMD 53.6 ohms 1/4W 1206 1%
 
|-
 
| RC1206FR-072K49L
 
| YAGEO
 
| ATTEN_40DB
 
| 1
 
| R1
 
| Resistors - SMD 2.49k ohms 1/4W 1206 1%
 
|-
 
| RK73H2BTTD51R0F
 
| KOA Speer
 
| ATTEN_40DB
 
| 2
 
| R2
 
| Resistors - SMD 1/4W 51 ohms 1%
 
|-
 
| RK73H2BTTDD49R9F
 
| KOA Speer
 
| ATTEN_50_60DB
 
| 2
 
| R2
 
| Resistors - SMD 49.9 ohms 1%
 
|-
 
| RC1206FR-077K87L
 
| YAGEO
 
| ATTEN_50DB
 
| 1
 
| R1
 
| Resistors - SMD 7.87k ohms 1/4W 1206 1%
 
|-
 
| RC1206FR-0726K1L
 
| YAGEO
 
| ATTEN_60DB
 
| 2
 
| R2
 
| Resistors - SMD 26.1k ohms 1/4W 1206 1%
 
|-
 
|}
 
 
 
=== Measurements ===
 
  
 
* NanoVNA
 
* NanoVNA
* S21 gain
+
** 12-16 MHz
* 1-900 MHz scan
 
* Calibrated with cable on thru
 
 
 
==== 40 dB Attenuator ====
 
 
 
* Flat from 1-600 MHz
 
* Higher attenuation past 600 MHz
 
* -39.9 dB at 14 MHz
 
* S21
 
 
 
[[file:ATTEN1_NanoVNA_40dB.png]]
 
 
 
* Flat from 1-30 MHz
 
* S21
 
 
 
[[file:ATTEN1_NanoVNA_40dB_1-30MHz.png]]
 
 
 
* s11
 
* 1-900 MHz
 
 
 
[[file:ATTEN1_NanoVNA_40dB_S11_1-100MHz.png]]
 
 
 
* VSWR
 
* 1-900 MHz
 
 
 
[[file:ATTEN1_NanoVNA_40dB_VSWR_1-100MHz.png]]
 
 
 
== DC Block ==
 
 
 
* Use same PCB
 
** Install 0.1uF cap between the two SMAs
 
* S21 of -0.8 dB at 50 KHz
 
* S21 of 0.44 dB at 900 MHz
 
 
 
[[FILE:ATTEN1_NanoVNA_DC-BLOCK_S21_50KHz-900MHz.png]]
 
 
 
== Attenuator Charts ==
 
 
 
[[file:dBm_vs_milliVolt_milliWatts.PNG]]
 
 
 
[[file:dBm_vs_Volta_Watts.PNG]]
 
  
[[file:dBm_vs_Volt_Watts.PNG]]
+
[[FILE:14MHz_12-16MHz_Band_Pass_Filter-2.png]]
  
== References ==
+
* Data
  
* [http://leleivre.com/rf_pipad.html Attenuator Calculator] - Le Leivre.com
+
[[FILE:14MHz_12-16MHz_Band_Pass_Filter-Data.png]]
* [https://www.pasternack.com/t-calculator-pi-attn.aspx Attenuator Calculator] - Pasternak
 
  
* Heavily inspired by Alan (W2AEW) video
+
[[FILE:  14MHz_12-16MHz_Band_Pass_Filter-Analysis.png]]
  
<video type="youtube">A5gGeV7CiQ0</video>
+
== Build Issues ==
  
[[file:W2AEW_Attns-01.PNG]]
+
* 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
  
[[file:W2AEW_Attns-02.PNG]]
+
== Reference Documents ==
  
[[file:W2AEW_Attns-03.PNG]]
+
* [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]
 +
* [https://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1991/12/page29/ The double-tuned Circuit: An experimenter's tutorial]
 +
* [http://hanssummers.com/polyphase 40/80m CW/SSB receiver]
 +
* [http://hanssummers.com/images/stories/polyphase/polyphase.pdf Experimental Polyphase Receiver]
 +
* [http://www.arrl.org/files/file/Technology/tis/info/pdf/030304qex020.pdf A Software Defined Radio for the Masses]
 +
* [http://norcalqrp.org/files/AustinNC2030Presentation.pdf Very High Performance Image Rejecting Direct Conversion Receivers] - NC2030 Radio

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