Channel Title: Unrelated Activities Channel Description: Unrelated Activities... Info about Weihrauch HW100 T FAC .22, Hatsan AT44 .177 and BT65 .22 peculiarities, maintenance and accessories (regulator valves, suppressors, scopes, mounts, etc), also CBC F18 B19S Standard and El Gamo 68 .177, Beeman P17, Crosman MK-177, pellets tests, ballistic coefficient, scope adjustments, and some other things like electronic projects (analog modular synthesizer, audio processing, guitar synthesizer and effects, GR-300, etc... Enjoy, like, share, subscribe!!!! Questions, suggestions, corrections are always welcome. <video> Electromagnetic Interference EMI filters Description: Through hole Electromagnetic Interference (EMI) T filters, frequency response on NanoVNA. Thanks for watching. </video> <video> Variable Tuning Capacitor from AM-FM radios - Polyvaricon Description: This is a variable capacitor used for tuning cheap AM/FM radios. I think Mitsumi coined the term "Polyvaricon" to name them. They are in fact four variable capacitors controlled by a single shaft. Thanks for watching. </video> <video> SDR receiver circuit test with small loop antenna Description: The SDR receiver circuit experiment so far: a rotary encoder connected to Arduino Nano controls the Si5351 quadrature VFO frequency (displayed on LCD), the quadrature signal drives two diode ring mixers performing direct conversion to a 0-96KHz baseband (no intermediary frequency (IF) here). The baseband is amplified by a 50 ohms input amplifier, its I-Q output then goes to the PC stereo souncard, and is processed by a SDR software (currently using HDSDR). The power supply, a linear PSU, provides regulated +12V to the RF circuitry, regulated +-12V to the baseband amplifier, and regulated +8V to the Arduino, that then provides regulated +5V to the LCD and Si5351 module. The front end has only one bandpass filter by now (~5MHz to 8MHz), a relay switches the BPF out when VFO frequency is outside BPF range. In this case, RF goes unfiltered to the termination insensitive amplifier, TIA. After amplification, a RF splitter send the RF signal to the two diode ring mixers. I need to find a way to put at least five switched frontend filters there... The VFO is capable of maintaining quadrature from 3.2 MHz to about 80 MHz. Hopefully, the splitter and mixers will also work up to 80 MHz. Maybe??? The test here goes from around 4MHz to 20MHz, way beyond the limits of the small shielded loop antenna. Thanks for watching. </video> <video> Ceramic Filter test with NanoVNA Description: I found this little black box among my junk bin of unidentified electronic components, and decided to try discover what it is. The code and marks are similar to those found in ceramic filters/resonators, but they usually have only two or three pins. This component has five pins... After finding what it was, the thing was tested with a NanoVNA Vector Network Analyzer. Thanks for watching. </video> <video> Small Loop Antenna test with NanoVNA Description: This is a loop antenna, the thing I have been using to pick some signals with the SDR receiver circuit experiment. It is the best HF antenna type for my situation (no space and too much noise) as it is small, directional, and can reject local noise to some extent. There is nothing special about it, no maths were harmed during its design, I just used the materials and space available to build it. The square loop (50cm sides) was made with RG59 75 ohm coaxial cable. The shield was cut right in the middle of the cable, leaving a 2.5cm (1") unshielded portion on the top center of the loop. The capacitor is a plastic tuning cap removed from an old AM radio. In conjunction with a parallel 33pF capacitor, capacitance range is from 300pF to 47pF. Let's test this antenna with NanoVNA. Thanks for watching. </video> <video> NanoVNA things and simple crystal test Description: NanoVNA things and simple crystal test. Thanks for watching. </video> <video> 13.560 MHz - What is this signal? Description: While testing my homemade phasing SDR receiver with a Moebius loop antenna, and without filters, I tuned to 13.560 MHz and got curious about what seems to be some form of time signal. Does anyone knows what it is, and its origin? Thanks for watching. </video> <video> 14 MHz 3rd order Butterworth bandpass filter for the SDR receiver experiment Description: Building a 14 MHz 3rd order Butterworth bandpass filter for the SDR receiver experiment. The method I've been using is to first choose a filter topology easy to build, in this case large bandwidth 3rd order Butterworth, input the data in a filter calculator like RFtools ( https://leleivre.com/rftools.html ), check if inductor values are not too high to be wound on small plastic toroid cores, then change input data until the calculated capacitor values match the capacitor values I have available. The filter frequency response is then checked in a circuit simulator, capacitors are measured, inductors are calculated using Coil32/64 software ( https://coil32.net/download.html ), measured with a homemade Arduino L meter and with NanoVNA LC shunt method. When everything is adjusted to result in acceptable parameters, the filter circuit is assembled in a test fixture and measured with NanoVNA. Thanks for watching. 00:00 - Intro 00:14 - RFTools filter design 00:32 - Circuit simulation 00:41 - Capacitance measurements 01:16 - Plastic toroid cores 02:29 - Coil32/64 toroidal air core inductor calculation 02:59 - Inductors assembled 03:49 - Arduino L-Meter 04:17 - LC tuned circuit resonant frequency 04:40 - NanoVNA LC shunt measurement 04:45 - pre calibration setup 05:29 - Calibration 06:14 - NanoVNA LC shunt measurement 06:33 - More inductance measurements Arduino L-MeterNnoVNA 07:06 - Bandpass filter test with NanoVNA 07:41 - Results 08:03 - Ending </video> <video> SDR circuit experiment update, schematics and Arduino code Description: Another update on the SDR (Software Defined Radio) receiver circuit experiment. Now there are two bandpass filters in the front end, for 20 meters and 40 meters. Both filters are third order Butterworth bandpass and each filter relay is activated by Arduino only when the Si5351 VFO frequency is inside the respective filter pass band. After the BPFs the signal goes to a 50 ohm, 15dB gain TIA (Termination Insensitive Amplifier), by Wes Hayward and Bob Kopski ( https://w7zoi.net/bidirectional_matched_amplifier.pdf ). Following the amp there is a 5th order 50 MHz Butterworth lowpass filter. A RF splitter then feeds two double balanced diode ring mixers. The VFO is a quadrature Si5351 VFO controlled by Arduino Nano. Videos covering some of the SDR experiment circuits: SDR 40m Front End test with NanoVNA https://youtu.be/_hCWGh8S6GQ Arduino Quadrature VFO with Si5351a clock generator https://youtu.be/WXq-T72pFLw Homemade Diode Double Balanced Mixer the synth ring modulator's real father, but for RF https://youtu.be/W31XW6yvzoY 14 MHz 3rd order Butterworth bandpass filter for the SDR receiver experiment https://youtu.be/LsE7yd_a0Ag Thanks for watching. </video> <video> More EMI Filters Description: More EMI Filters, blue ones from TDK. Thanks for watching. </video> <video> Small Receiving Loop Antenna with Matching Variable Capacitor - Test with NanoVNA Description: This is the small loop receiving antenna I've been using with the the SDR circuit experiment. There is already a video with description and tests on this channel: https://youtu.be/GO0t0hLeKLw In short, it is a square loop with 50cm side, made with 75 ohms RG59 coaxial, which shield was cut right at the center. The separated shields are connected at output ground, the inner conductor ends are connected to a variable capacitor for tuning (~5 MHz to ~9MHz). As I got another variable capacitor ( https://youtu.be/8e86SSvQp5Y ), it is time to try a simple modification by including it as an impedance matching capacitor. The impedance matching capacitor is inserted in series with the output. Another change is the P2 conductor/C1-2 end connection to ground. This is supposed to improve balance, so worth trying. Both variable capacitors are from portable AM radios and adjustment is not exactly smooth. The impedance matching capacitor would definitively benefit from a reduction gearbox of some sort, but works as intended. Tests were made with NanoVNA vector network analyzer. Thanks for watching. </video> <video> Front end band-pass filter with shielded variable inductors from IFTs Description: I found a set of seven little boxes that look like IFTs (Intermediary Frequency Transformers), but were wound as variable inductors. They worked as oscillator inductors for the short wave section from a TA2003 based AM/FM portable radio made by Toshiba ( TR-949GL ). In this video I will test them building a 3rd order Butterworth bandpass front end filter covering the lower band for the SDR receiver I am building: 3.2 MHz to around 5.8 MHz. All measuring done with a NanoVNA. Thanks for watching. </video> <video> IFTs - Intermediary Frequency Transformers, look inside and test with NanoVNA Description: A small collection of IF transformers. Most are from radio circuits, some are probably from old TV and video recording devices, the older ones in this collection are from mid 1970's. Most were made by Toko. Although specifications can vary wildly, all of them have the same basic structure: a cylindrical former inside a metallic shield, and a ferrite cup or rod for tuning. The former where the transformers are wound can be made from ferrite or plastic material. Some have a capacitor in parallel with the transformer primary winding.Other can be just variable inductors. In this video we have a look inside the transformers and test one exemplar with NanoVNA. Thanks for watching. </video> <video> Testing Another Homemade RF Power Splitter for the SDR Receiver Experiment Description: In this video, another homemade RF power splitter for the SDR receiver experiment is tested. This time the splitter was made using toroid ferrite cores instead the binocular ferrite cores used in the last video. The cores for the new splitter have a higher AL, about 850, so the transformers were wound with half the number of turns (7T tap 5 from ground for the impedance matching transformer and 5T bifilar for the splitter) and using a thicker wire (~0.5mm). Tests were made using the NanoVNA (Vector Network Analyzer), same way as last video: https://youtu.be/ez3inK15DNA Thanks for watching. </video> <video> 10.7MHz FM IF ceramic filters test with NanoVNA Description: Testing two 10.7MHz FM IF ceramic filters, E10.7S and E10.7A, with NanoVNA. These passive electronic components are used as IF (Intermediary Frequency) filters in FM (Frequency Modulation) radio receivers. 3dB bandwidth can be around 100 KHz to 300 KHz, depending on model and tolerance. Thanks for watching. </video>

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Unrelated Activities...

Info about Weihrauch HW100 T FAC .22, Hatsan AT44 .177 and BT65 .22 peculiarities, maintenance and accessories (regulator valves, suppressors, scopes, mounts, etc), also CBC F18 B19S Standard and El Gamo 68 .177, Beeman P17, Crosman MK-177, pellets tests, ballistic coefficient, scope adjustments, and some other things like electronic projects (analog modular synthesizer, audio processing, guitar synthesizer and effects, GR-300, etc...

Enjoy, like, share, subscribe!!!!
Questions, suggestions, corrections are always welcome.

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