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18 Jul 2020 08:14:04 UTC
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QCX Transceiver Part 6 - Low Pass Filter and Alignment
In this video the low pass filter is installed and the receiver is run through the alignment process.
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https://www.youtube.com/watch?v=hUIWjrWkY84
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https://www.youtube.com/watch?v=hUIWjrWkY84
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https://qrp-labs.com/qdx.html
Here's the manual and operating guide
https://qrp-labs.com/images/qdx/manual_1_11.pdf
https://qrp-labs.com/images/qdx/manual_operation_1_03.pdf
0:00 Intro and QDX description
1:00 Walkthrough of board
2:27 A look under the microscope
4:18 Walkthrough of schemartic
7:36 My build order (done at my own risk ;) )
11:07 uController up and running
13:40 Quick walkthrough of LPF switching
16:17 Building the LPF
17:10 Winding the LPF toroids
18:00 Testing the LPF toroids
16:35 Installing L12 the multi-tap bandpass inductor
23:08 Winding the Trifilar splitter T2
26:06 Determining T2 leads
28:46 *** On the Air ***
30:40 Doing some voltage measurements - LPF
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33:57 Testing X6
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https://www.ti.com/lit/ds/symlink/opa2674.pdf?ts=1637860124805&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FOPA2674
0:00 Intro
0:37 Driver circuitry schematic walkthrough
1:20 Detail of Op-amp driver and gain
2:20 Bias circuitry on Schematic
3:52 Build and testing order
5:53 Testing the supply to Opamps and to center tap of T4
8:07 OPA2674 Opamps installed and tested
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12:12 Q10 p-channel bias switch mosfet installed and tested
13:58 Gate bias circuitry installed
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https://www.youtube.com/watch?v=zRPuAX_Dfn4&t=778s
To the IRF510 based amplifier
https://www.youtube.com/watch?v=D4UhOmum_oU&t=1s
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I was planning on comparing the results above with a commercial radio (a KX3 in this case) but I never got around to it. If there's anyone interested let me know in the comments.
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1:53 Two tone on oscilloscope
2:33 Two tone on spectrum analyzer
3:28 Harmonic calculations
4:06 Effect of I/Q balance on a single tone signal
4:43 Effect of adjusting IRF510 gate bias
5:03 Bias adjust on the oscilloscope
6:34 Bias adjust on the spectrum analyzer
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Huge thank you to "YetAnotherElectronicsChannel" series of DSP videos:
https://www.youtube.com/channel/UCwOkALY6oQbOL1zU7ApaPHg
This is the board I am using:
https://www.st.com/content/st_com/en/products/evaluation-tools/product-evaluation-tools/mcu-mpu-eval-tools/stm32-mcu-mpu-eval-tools/stm32-nucleo-boards/nucleo-f767zi.html
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https://store.digilentinc.com/pmod-i2s2-stereo-audio-input-and-output/
SMTCubeIde link (free download)
https://www.st.com/en/development-tools/stm32cubeide.html
CMSIS Library (look for the ""pack" file):
https://github.com/ARM-software/CMSIS_5/releases
The code
https://github.com/thaaraak/F7-DSP
A link to the microphone amplifier circuit I built up
https://www.youtube.com/watch?v=unRe5Pc66-g&t=1s
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0:00 Intro
4:40 I2S background
6:54 PMod I2S2 Audio Board
9:15 Connections between PMod and Nucleo
13:27 STMCube
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In this video I wrap up the build, get it on the air and even make a QSO!
Here's where I bought the genuine RD15HVF1s from
https://www.rfparts.com/rd15hvf1-501.html
RD15HVF1 datasheet
https://www.mitsubishielectric.com/semiconductors/content/product/highfrequency/siliconrf/discrete/rd15hvf1.pdf
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1:08 A note on RD15HVF1s genuine and otherwise
3:59 Pinout of genuine RD15HVF1 and copy
4:57 T1 Wound and Installed
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7:32 T5 Wound and installed
10:03 T5 tested on the board
10:40 Power supply filtering
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14:54 Two tone test
16:08 Low pass filters
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18:47 Getting the magnis on the Air
19:15 Some listening
20:41 A QSO (hope you don't mind me sharing our QSO, John)
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Transaction
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