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

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[[File:RF-Amp_Front.png]]
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[[file:QRP-Labs_P1956-720px.jpg]]
  
== RF Amplifier Features ==
+
== Features ==
  
* From [https://zl2ctm.blogspot.com/2020/11/go-qrp-portable-ssb-rig.html Charlie Morris' (ZL2CTM) Go QRP Portable SSB Rig]
+
* Three modules
** Solid State Design for the Radio Amateur?
+
** [http://qrp-labs.com/receiver QRP Labs High Performance Receiver Module]
* +22 dB gain
+
*** Direct Conversion Receiver
* Input connectors: SMA or BNC
+
*** Uses a Quadrature Sampling Detector (QSD), also known as a Tayloe Detector
* 49x49mm card
+
*** [https://www.onsemi.com/pdf/datasheet/fst3253-d.pdf FST3253] Mixer is arranged as a double-balanced mixer for maximum performance
* 4x 4-40 mounting holes
+
*** 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
  
== RF Amplifier Design ==
+
=== Build / Assembly ===
  
=== Schematic ===
+
* 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]
  
[[file:RF_Amp_Schematic-4.PNG]]
+
== Silkscreen / Pinout ==
  
=== Input/Output Transformer ===
+
[[file:IQ_RX_PCB.PNG]]
  
==== FT37-43 Toroid ====
+
=== Pins ===
  
* [http://toroids.info/FT37-43.php FT37-43]
+
* IQ pins
* Wideband Transformers 5 - 400 MHz
+
* I, GND, Q outputs
* Power Transformers 0.5 - 30 MHz
+
* Power pins
* 10 turns = 35uH
+
* 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
  
[[file:FT37-43_10_Turns.PNG]]
+
== Receiver Module ==
  
==== Tracks ====
+
[[file:QRP-Labs_Receiver-Base_P1969-720px.jpg]]
  
[[file:RF-Amp-tracks.PNG]]
+
== Polyphase Module ==
  
==== Input Transformer ====
+
*  Important to observe part outlines
 +
** Adjacent resistors can be put in "sideways"
  
** Input Transformer (T1 on Charlie's - T2 on this board)
+
[[file:QRP-Labs_Polyphase-Filter_P1966-500px.jpg]] [[file:Polyphase-pcb.PNG]]
***  50:75.8 Ohms = 1 : 1.23 turns ratio
 
**** 9 turns primary, 11 turns on secondary
 
  
[[file:RF-Amp-T2.PNG]]
+
[[file:Polyphase-pcb-2.png]]
  
==== Output Transformer ====
+
[[file:Polyphase-Schematic.PNG]]
  
** Output transformer (T2 on Charlie's - T1 on this board)
+
* USB/LSB select jumpers
*** 200:50 Ohms = 2:1 turns ratio
+
** Set to USB in the above picture
*** 10 turns primary (on transistor collector), 5 turns secondary (towards output)
 
  
[[file:RF-Amp-T1.PNG]]
+
[[file:Polyphase_LSB-USB-Jumpers.PNG]]
  
== LT Spice Simulation ==
+
== Bandpass Module ==
  
* [https://github.com/land-boards/lb-boards/blob/master/HamRadio/RF-Amp/LTSpice/2n3904%20amp.asc LTspice Simulation] - GitHub source file
+
* 20M - 14 MHz Filter
  
=== Transformers ===
+
[[file:QRP-Labs_BandPass-Filter_P1963-720px.jpg]]
  
[[File:RF-AMP-LTSPICE_XFMRS.PNG]]
+
[[file:Bandpass_Filter_Schematic.PNG]]
  
== Charlie Morris Design ==
+
* NanoVNA
 +
** 12-16 MHz
  
* From Charlie's notes with mods for my use
+
[[FILE:14MHz_12-16MHz_Band_Pass_Filter-2.png]]
** [https://zl2ctm.blogspot.com/2020/11/go-qrp-portable-ssb-rig.html Charlie Morris' (ZL2CTM) Go QRP Portable SSB Rig]
 
* [https://www.mouser.com/datasheet/2/308/1/2N3903_D-2310199.pdf 2N3904 data sheet]
 
  
=== Beta DC ===
+
* Data
  
* Geometric mean min/max beta at operating current
+
[[FILE:14MHz_12-16MHz_Band_Pass_Filter-Data.png]]
** =sqrt(100*300) = 173
 
  
=== Beta AC ===
+
[[FILE:  14MHz_12-16MHz_Band_Pass_Filter-Analysis.png]]
  
* Gain bandwidth product divided by operating frequency
+
== Build Issues ==
** Assume operating frequency of 10 MHz (my IF is actually at 9 MHz)
 
** = 300/10 = 30
 
  
=== DC Operating Point ===
+
* 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
  
* CE current 10 mA
+
== Reference Documents ==
** If Vce = 6V, this is 60 mW power dissipation
 
* Assume Ve (voltage across emitter resistor) = 1/10 Vcc = 12V/10 = 1.2V
 
*** R3 is Re (emitter resistor) = 1.2V/0.01A = 120 ohms
 
* VCE = 0.7V (typical from data sheet)
 
* V(emitter) = 1.2V
 
* V(base) = V(emitter) + VCE = 1.9V
 
* Assume current in biasing resistors = 10x current needed by DC beta
 
** 10 mA in C-E, beta DC less = 10 mA/173 = 48 uA
 
** 10x the current in the biasing resistors = 480 uA (calculated)
 
* R2 is 1.9V at 480 uA = 3.9K use 3.3K
 
** Actual current will be 1.9V/3.3 ohms = 634 mA
 
* R1 sources current to R2 and transistor base
 
** Voltage = Vcc (12V) - 1.9V = 10.1V
 
** Current = 576 uA + 57 uA = 634 uA
 
** R1 = 10.1 / .634 mA = 15.9K, use 15k
 
  
=== Input resistance ===
+
* [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]
* Parallel resistors R1, R2 paralleled with transistor input impedance
+
* [https://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1991/12/page29/ The double-tuned Circuit: An experimenter's tutorial]
** R1=15K, R2=3.3K
+
* [http://hanssummers.com/polyphase 40/80m CW/SSB receiver]
** Transistor resistance = Beta AC (30) times re
+
* [http://hanssummers.com/images/stories/polyphase/polyphase.pdf Experimental Polyphase Receiver]
*** re = 26 / Ie (10 mA in mA) = 26/10 =
+
* [http://www.arrl.org/files/file/Technology/tis/info/pdf/030304qex020.pdf A Software Defined Radio for the Masses]
*** Beta AC * re = 30*2.6 = 78 ohms - predominates
+
* [http://norcalqrp.org/files/AustinNC2030Presentation.pdf Very High Performance Image Rejecting Direct Conversion Receivers] - NC2030 Radio
** All in parallel are 75.8 ohms
 
 
 
=== Transformers ===
 
 
 
* T1 50:75.8 ohms
 
** n = sqrt(Zout/Zin) = sqrt(75.8/50) = 1.23
 
** 9:11 turns ratio
 
* T2 - different than Charlie's design since my Crystal filters are all 50 ohms in/out
 
** 250:50 ohms
 
** n = sqrt(250/50) = 2.23:1
 
** 11:5 turns
 
 
 
=== Charlie's Notes ===
 
 
 
[[FILE:IF Amp_0046A.jpg]]
 
 
 
[[FILE:IF Amp_0046B.jpg]]
 
 
 
[[FILE:IF Amp_0046C.jpg]]
 
 
 
[[FILE:IF Amp_0047A.jpg]]
 
 
 
[[FILE:IF Amp_0047B.jpg]]
 
 
 
[[FILE:IF Amp_0047C.jpg]]
 
 
 
== Video ==
 
 
 
<video type="youtube">CHdtoupH2Vg</video>
 
 
 
<video type="youtube">YJTsWV2kzFY</video>
 
 
 
<video type="youtube">xPFzFhM0ojE</video>
 
 
 
== Assembly Sheet ==
 
 
 
* [[RF Amplifier Assembly Sheet]]
 

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