#183: Why diodes are used around relay coils: Back to Basics on flyback or snubber diodes w2aew 2024-10-17 | #183: Why diodes are used around relay coils: Back to Basics on flyback or snubber diodes
#386: Build the Iambic pressure paddle from VK3IL w2aew 2024-06-01 | This short video presents the VK3IL Pressure Paddle - a lightweight portable paddle for your amateur radio's iambic keyer (for CW / Morse Code). This paddle is perfect for the portable POTA and SOTA operator, as it is small and uses no moving parts. The author's blog page for this project can be found here:vk3il.net/pressure-paddle-v2The link to order the exact board I used here is:oshpark.com/shared_projects/ch6BPBtLHere's the link for the longer version of the board:oshpark.com/shared_projects/zdbRih8hThe list of parts I ordered from Digikey:http://www.qsl.net/w2aew/youtube/VK3IL_parts_Digikey.png
#385: How to quickly tune the Penntek TR-45L Z-match tuner w2aew 2024-04-22 | This short video shows how to quickly adjust the Z-match tuner in the Penntek TR-45L by slightly "overshooting" the null which each knob adjustment. Of course, you want to finish up with the deepest null possible (little to now REV power deflection). This technique helps you get close to this point quickly - then finish up at the lowest possible REV power.
#384: What is the bandwidth of a CW / Morse code signal? (as a function of speed and rise/fall time) w2aew 2024-03-28 | The occupied bandwidth (OBW) of a CW / Morse code signal is primarily dependent upon the keying speed (Words per minute / WPM) and the rise/fall time of the RF envelope. Radios and operator practice give you control over the WPM, but not many radios give you control over the RF rise and fall time (which can have a major effect). This video shows measurements of the Occupied BW at various keyer speeds and RF rise/fall times. Equipment used in this video include:Tektronix MSO44B oscilloscope: tek.com/en/products/oscilloscopes/4-series-msoTektronix AFG31252 Arbitrary Waveform Generator:tek.com/en/products/signal-generators/arbitrary-function-generator/afg31000Notes from this video:http://www.qsl.net/w2aew/youtube/OBW-of-CW-signals.pdf
#383: Measuring AM Modulation Depth using an Analog Oscilloscope (followup from #382) w2aew 2024-03-06 | This is a followup from video #382 where I demonstrate how to measure Am modulation depth using a digital oscilloscope. In this video, we take a look at how to perform the measurement with an older analog scope (Tektronix 485). Additionally, the measurements will be performed on low-cost RF signal generators. Here is a link to the previous video:youtu.be/-D-hkFkCH7I?si=zAfmYw0BeVA9Ar7G
#382: Measuring AM modulation depth/percentage with a digital oscilloscope w2aew 2024-03-02 | This video shows how to measure the modulation index/percentage of an AM (amplitude modulated) RF carrier. The basics of the calculations are shown, as well as techniques for setting up the scope to get a high quality waveform for the measurement. Notes for the video can be found here:http://www.qsl.net/w2aew/youtube/AMmeasurement.pdfRelated videos:youtu.be/i29pI7okLe4?si=0zx-4RscFinQ21rTyoutu.be/0Kk_N_TpDeo?si=i_Rqp7_pMLldRHbt
#381: Circuit Fun Followup: Trimming out distortion on Twin-Tee Oscillator - FFT &THD measurement w2aew 2024-02-19 | This is a followup to the previous video on the Twin-Tee oscillator:youtu.be/KFVVozlXoOk?si=WV0abgPCMmj5OQxJ...showing what happens in the FFT and the THD measurement as the trimmer is adjusted in the Twin-Tee network (by request).
#380: Circuit Fun: Twin-Tee Oscillator - low distortion op amp sine waves w2aew 2024-02-17 | This circuit fun video presents the Twin-Tee op amp oscillator - a fun circuit that can make low distortion (low THD) sine waves with simple resistors and capacitors, no inductors. It is a circuit you don't see written up too much.Here is a link to the Texas Instruments article shown in the video:http://www.ti.com/lit/pdf/slyt164More appnotes on sine wave oscillators...ti.com/lit/SLOA060ti.com/lit/an/snoa665c/snoa665c.pdfMy show notes:http://www.qsl.net/w2aew/youtube/twintee_oscillator.pdfRelated FFT and THD videos on my channel:youtu.be/oRf-IpG6XAw?si=eM0TJF6JYi-yLC7kyoutu.be/s_cVP5gu4SY?si=rsxHSVUB_6KL4tEMyoutu.be/EqRvUyPhbu8?si=1AgOOXLWbkq-W_3U
#379: How to measure coax loss using a NanoVNA w2aew 2023-12-23 | This video shows how to setup your NanoVNA to measure coax loss using an S21 measurement on a VNA. I show the setup and calibration process, as well as some actual measurements of a few lengths of RG-174 and RG-316 coax that I use for my portable (POTA) HF operating. More info on the custom NanoVNA stand here:forums.qrz.com/index.php?threads/3d-printed-stand-for-nanovna-h4-w-small-tray-your-call-sign.86169800:00 Introduction00:18 Credit and Inspiration for the video00:54 Coax samples to be measured01:24 Hardware setup for calibration and measurements02:55 Setting up the frequency range03:23 Running the Calibration05:03 Setting up the Traces and Markers06:54 Making the loss measurements on the samples of coax09:28 Summary10:39 Thanks given for the NanoVNA stand
#378: Ham Radio: Measuring CW Keyer speed on the Elecraft KX2 and Penntek TR-45 Lite w2aew 2023-12-03 | This video shows how I measured the morse code keyer speed in my Penntek TR-45L and Elecraft KX2 QRP rigs. The Reverse Beacon Network spots always seemed to indicate a WPM (word per minute) speed that was faster than the speed setting on these rigs - so I wanted to measure them to see which was right. The basic timing calculations can be found in this web resource:https://morsecode.world/international/timing.htmlThe RF Sampler that I used is similar to this:rfparts.com/signal-samplers/rfa4059a.htmlNotes from this video can be found here:http://www.qsl.net/w2aew/youtube/MeasureKeyerSpeed.pdf
#377: How to install a crimp-on BNC connector to RG-8X coax cable w2aew 2023-11-30 | This video shows how to install a crimp-on type BNC male connector onto RG-8X coax cable. The connector shown is available from Max-Gain Systems. The specific connector used here can be found at:mgs4u.com/product/bnc-male-crimp-connector-for-0-240-inch-od-coax-7005-bnc-8xThe installation guide, datasheet, etc. can all be found on this page as well.
#376: Ham Radio: Build, Tune and Test a QRP End Fed UNUN kit from KM4CFT w2aew 2023-11-05 | In this video I show the assembly, tuning and successful operation of a new QRP End Fed UNUN kit from KM4CFT. The kit can be assembled as a 49:1 UNUN for end-fed halfwave (EFHW) or as a 9:1 UNUN for end-fed random-wire (EFRW) antennas. I chose to build it as a 49:1 for EFWH applications. Please note that the 2mm banana plug/jack is NOT included in the kit, nor is the wire for the antenna itself. Here is the link to purchase the kit:ebay.com/itm/325869783066Here is the link for the very detailed build instructions:radiodan.com/pdf/KM4CFT%20EF%20Antenna%20Assembly%20Instructions_10-31-2023.pdfHere is a really nice wire winder that pairs nicely with this antenna (3D printer required):printables.com/model/320604-wire-antenna-winder-with-female-bnc-clip
#375: Ham Radio Quickie: Ground Radial wires vs. the Magic Carpet Faraday cloth w2aew 2023-10-31 | Just a quick video to document my quick comparison of portable vertical antenna VSWR sweeps using my ground radials vs. a conductive fabric mat, often called a "magic carpet". Note that these results are specific to my antenna configuration, your results may vary. I kept "everything" constant/unchanged between the two configurations to get an apples-to-apples comparison.
#374: Back to Basics: JFET Current Source / Limiter circuits w2aew 2023-10-16 | This video discusses the JFET current source / limiter circuits, illustrating the very simple circuit structure, its operation, and the pros and cons of these circuits. The background videos that may be helpful to review would be:Intro to FETs:youtu.be/oambDFa0Pr8?si=gdJTDa-F7z9F5GHRTransistor (BJT) Current Sources and Mirrors:youtu.be/xR0RfmmRhDw?si=e60AFMoc2qGG-HZiyoutu.be/JbCI4Lsnqho?si=y-6FlsQT0VZXRw7QThe notes from this video can be found here:http://www.qsl.net/w2aew/youtube/JFET-Current-Sources.pdfBONUS! 50uA Current Source, like the one to calibrate Simpson 260 VOM, built using a single JFET and the cascode design, traced out on the curve tracer, including a zoom in to 1uA/div:http://www.qsl.net/w2aew/youtube/50uA_curves.pdfThe Siliconix AppNote on JFET current sources:vishay.com/docs/70596/70596.pdf
#373: Portable ham radio / POTA: The Spiderbeam 40 (12m) telescoping mast and hitch mounted support w2aew 2023-10-02 | This short video shows my new Spiderbeam 12 meter (40 foot) telescoping mast, and the trailer-hitch mounted support that I plan to use to support wire antennas for portable / POTA operations. I modified the "flagpole" mount to better accommodate the 40' tall mast. The specific products I used in this video are:Spiderbeam mast:http://www.vibroplex.com/contents/en-us/p3532.htmlFlagpole mount for 2" receiver:amazon.com/dp/B004IVGA0G?psc=1&ref=ppx_yo2ov_dt_b_product_detailsPS: Found the following 3D printed collar that was designed specifically for the 40' Spiderbeam and this particular mount:thingiverse.com/thing:6057015
#372: How to install an N-connector, crimp-on type, to LMR-600, RG-217 or similar coax cable w2aew 2023-09-05 | This video shows how to install a crimp-on style N-male connector onto coaxial cable - specifically LMR-600, RG-217/U or other 0.59" cable types. Other coax styles will be similar, but may have different strip dimensions. Always consult the installation guide. The connector shown is from Max-Gain Systems:http://www.mgs4u.com
#371: Ham Radio Quick Tip: Tuning aid for Adjustable Coil vertical like the MP1 and others w2aew 2023-07-24 | Here's a quick tip showing a homemade adjustment gauge for an adjustable coil vertical like the SuperAntenna MP1 shown, which is one of the antennas I carry for POTA activations. The same type of gauge can be made for antennas such as the Wolf River Coil and others. Of course, this assumes that you've already measured and documented the coil tap positions for the bands you choose to operate on. The coil shown in the video is part of this antenna:http://newsuperantenna.com/Super-Antenna-MP1
#370: FX-4CR Transceiver PCB replacement procedure w2aew 2023-07-23 | The FX-4CR is the updated version of the FX-4C by BG2FX that I previously reviewed in this video:youtu.be/sPL5eMqU6gcThe "CR" version includes a wider waterfall spectrum, built-in Bluetooth, up to 20W output and more. See the product webpage for more info:bg2fx.com/fx-4cr-transceiverThere was a small hardware improvement made on this rig after the initial production run. The designer graciously sent the owners of the early units an upgraded circuit board. This video shows how to replace it.
#369: How to install a crimp-on BNC connector to RG-316, RG-174, etc. coax w2aew 2023-06-21 | This video shows how to install a crimp-on style BNC connector onto RG-316 coaxial cable, or other 0.100" OD coax such as RG-174, RG-188, Belden 83269, 83284, 84316, etc. The connectors used here were purchased from Max-Gain Systems in Marietta, GA (no sponsorship or other relationship to W2AEW). I found their prices to be good, and quality of the connectors appears to be very good. Their website is:http://www.mgs4u.comThe particular connector used in the video is their p/n: 7005-BNC-174
#368: Overview of the Peak Atlas DCA Pro Model DCA75 Semiconductor Component Analyzer & Curve Tracer w2aew 2023-05-18 | This is a brief overview of the Peak Atlas DCA Pro semiconductor component analyzer, the model DCA75 from Peak Electronics. Some brief comparisons to the inexpensive multi-function testers available today as well as a large full-blown curve tracer, as we take a look at the basic and advanced features of this great little tester.The unit shown in this video is an older version of this:peakelec.co.uk/acatalog/dca75-dca-pro-semiconductor-analyser.htmlAmazon link:amazon.com/Atlas-ADVANCED-SEMICONDUCTOR-ANALYZER-Tracing/dp/B00O0BMNX2The inexpensive tester shown is essentially this:amazon.com/Mega328-Digital-Transistor-Resistance-Capacitance/dp/B07WT9VVZBThe Tektronix Model 576 Curve Tracer is:w140.com/tekwiki/wiki/576A more complete video on the 576 can be found here:youtu.be/c-y8UmoHbtw
#367: Characterizing the key-up frequency transient on an Alinco DR-135 Mk III 2m radio with an RSA w2aew 2023-04-09 | A fellow ham reported some transient interference coming from a local digipeater that was using the Alinco DR-135 2m FM transceivers. He found that they had a significant frequency instability at key-up, and asked me to verify and document this in a video. This video takes a look at two different DR-135 rigs. I also take a look at an older Kenwood TM-231A and an Icom rig for comparison. It is clear from this video that the Alincos definitely have a serious frequency instability upon key up of the transmitter. A Tektronix RSA306B and the companion SignalVu-PC software is used to characterize the units.
#366: Back to Basics: Basics of the Bipolar Transistor - NPN and PNP w2aew 2023-03-11 | NOTE: The horizontal axis of the characteristic curve plot were mislabeled as Vbe instead of Vce in one or two spots. The downloadable video notes have been corrected. This is a back-to-basics tutorial video on the bipolar junction transistor, or BJT. While there are just two basic types (NPN and PNP), the video mainly discusses NPN types. It reviews the schematic symbol, typical pinouts, & basic operating principles of linear and switch operation. We dip our toe into the physics a little bit, and then do some experiments on the bench to demonstrate the linear and switch / saturation mode of operation. Links to the notes and other videos appear below the chapter listing:00:00 Introduction00:09 Types of Bipolar Junction Transistors (BJTs) - NPN and PNP00:39 Schematic symbols and transistor terminal names01.06 Common package pinouts02:05 The common diode or junction diagram02:43 Basic principles of operation of the bipolar transistor03:50 Linear and Switch regions of operation04:54 Transistor characteristic curves06:37 Linear operation details09:41 Brief look at the physics of operation12:51 Summary of the physics13:14 Linear test circuit schematic14:15 Demonstration of linear operation17:30 Switch / Saturation region of operation19:04 Saturation test circuit schematic19:28 Demonstration of switch / saturation operation21:15 More bipolar transistor videos23:07 ClosingVideo Notes:http://www.qsl.net/w2aew/youtube/Bipolar_Transistor_Basics.pdf
#365: Ham Radio: What is your CW straight key sending style? w2aew 2022-12-31 | This video poses the question - how do you operate your straight key when sending Morse Code (CW)? There are a LOT of ways to do this. I show a few common techniques, but there certainly are more variations. What do you do?More about Straight Key Night:http://www.arrl.org/straight-key-nightMy video on the Basics of Morse Code:youtu.be/78VXLVZckIQ
#364: Ham Radio quickie: Single Sideband (SSB) receive audio quality on the Penntek TR-45L w2aew 2022-12-17 | My previous video gave a comprehensive review of the new Penntek TR-45 LITE 5-band CW-only transceiver. The receiver can be used for SSB listening, and a few viewers asked how the audio quality for SSB sounded. Here is a sample of that.
#363: Ham Radio Review: The Penntek TR-45 Lite 5-Band, 5-Watt CW portable QRP transceiver w2aew 2022-12-11 | This is a short review of the new Penntek TR-45L 5-band, 5-watt, CW QRP transceiver produced by WA3RNC. We take a look at the physical characteristics, and the completely menu-less operation of the rig. Such a fun transceiver to operate! Production expected to begin for factory wired/aligned units in early 2023, to be followed by kit availability shortly after that. For more information, visit the product webpage:wa3rnc.com/store/penntek-tr-45l-qrp-transceiverInside pics:http://www.qsl.net/w2aew/youtube/TR-45L-1.jpeghttp://www.qsl.net/w2aew/youtube/TR-45L-2.jpeghttp://www.qsl.net/w2aew/youtube/TR-45L-3.jpeg
#362: Ham Radio: My Elecraft KX2 portable QRP shack kit for Parks On The Air (POTA), SOTA, and more w2aew 2022-11-20 | This video shows my Elecraft KX2 "shack in a pack" kit for QRP portable operations, such as Parks On The Air (POTA), Summits On The Air (SOTA) and other portable operating activities. Some of the items included in this kit are:The Elecraft KX2: elecraft.com/products/kx2-ssb-cw-data-80-10-m-transceiverThe Spark Plug Gear 49:1 UNUN Transformer:sparkpluggear.com/shop/p/sparkplugThe BaMaKeY TP-III Paddles:bamatech.net/morsetasten/bamakey-tp-iii-twin-paddle-key-rot.html?language=enMini Camelback straight key:http://www.vibroplex.com/contents/en-us/p3527.html40m EFHW antenna:threemosquitos.com/our-products/efhwSmall reporter's notebooks:amazon.com/dp/B007XUB9VO?psc=1&ref=ppx_yo2ov_dt_b_product_detailsMy portable operating backpack:youtu.be/yIZVBKND_II
#361: Ham Radio: My first Parks On The Air (POTA) activation! At Barnegat Light, POTA K-1609 w2aew 2022-08-18 | This short video is just a few short clips from my first "activation" of a park for the amateur radio Parks on the Air (POTA) activity. This is where hams will setup at a designated park and setup a station (activator) and try to make a number of contacts with other hams (hunters and other activators). This was my first time being an activator. I was at Barnegat Light State Park, on the north end of Long Beach Island off the coast of NJ (Park K-1609). Learn more about Parks on the Air here:parksontheair.com
#360: Mini Review: The BaMaKey TP-III miniature Morse Code paddles/key by BaMaTech w2aew 2022-08-06 | This is a short review of a miniature set of Morse Code keying paddles from BaMaTech made in Germany. This beautifully made iambic paddle will be ideal for my future portable ham radio operating activity.Website: bamatech.net/morsetastenLearn more about Morse Code and Iambic keying:youtu.be/78VXLVZckIQMy diagram for the TP-III mechanism:http://www.qsl.net/w2aew/youtube/bamakey-TP-III.pdf
#359: Quick Tip: Selecting 10x passive probes for your oscilloscope - Bandwidth and Compensation... w2aew 2022-07-24 | This video answers the most common questions I get about oscilloscopes and probes... What BW probe should I get? Can I use a probe with a BW that is different than my scope BW, etc. One important consideration presented in the video is ensuring that the probe can be properly compensated. Here are videos that I have done in the past on probe compensation:youtu.be/oxJQr4dKnysyoutu.be/SX4HGNWBe5M
#358: Ham radio: How to install the Roofing Filter kit in the Elecraft KX3 Transceiver w2aew 2022-07-10 | This video shows how to install the Elecraft KXFL3 Roofing Filter in the KX3 transceiver. It shows the physical installation along with the software alignment / sideband nulling process.Elecraft KX3: elecraft.com/products/kx3-all-mode-160-6-m-transceiverRoofing Filter kit:elecraft.com/products/kxfl3-dual-roofing-filter-for-the-kx3?variant=50783314699Definition of a roofing filter:en.wikipedia.org/wiki/Roofing_filter
#357: Ham Radio fun: ARRL Field Day 22 - Antenna raising, rig setup and a bit of operating w2aew 2022-06-26 | Here's a short video showing a bit of my "solo" Field Day setup at the Guglielmo Marconi Memorial Park in Franklin Twp NJ - former site of the Marconi Wireless Corp East Coast transmitting station. Equipment used in this video:FX-4C SDR Transceiver:bg2fx.comPar End-Fed Tri-band antenna:http://www.vibroplex.com/contents/en-us/p3412.htmlMiniature "Camelback" morse code key:http://www.vibroplex.com/contents/en-us/p3527.htmlMini Iambic Paddles:amazon.com/Mini-Key-Automatic-Morse-Stainless/dp/B09KC3JYC8Emtech ZM-2 Antenna Tuner:steadynet.com/emtech/zm2-kit-uhf-connectorsBattery:bioennopower.com/collections/12v-series-lifepo4-batteries/products/12v-8ah-lfp-battery-abs-sealed-black-case
#356: Back to Basics: the Emitter Follower, or Common-Collector Amplifier w2aew 2022-06-13 | Inspired by a friend's question from the book "The Art of Electronics", here is a back-to-basics video on the BJT (bipolar junction transistor) Emitter-Follower, or Common-Collector amplifier. Some useful video links for background on some of the topics presented are:Bipolar C-E amplifier biasing:youtu.be/c6cmkm3UPUIComparing Common Emitter, Common Base and Common Collector amps:youtu.be/zXh5gMc6kyUCommon Emitter design hints and tricks:youtu.be/VWY2WQcKJgkVbe Multiplier - and push-pull amp biasing:youtu.be/Obh_PIC2qqoNotes from this video:http://www.qsl.net/w2aew/youtube/Basics_of_emitter_follower.pdf
#355: Radio Review: FX-4C SDR QRP Transceiver | Review of features and operating controls w2aew 2022-06-03 | Review of the features and operating controls of the FX-4C - a great little SDR Transceiver designed by BG2FX. NOTE that I mis-stated the transmit range in the video. This rig does NOT transmit on the 6m band. It transmits only on the 80, 60, 40, 30, 20, 17, 15, 12 and 10m bands. The homepage and purchase link can be found here:bg2fx.com
#354: Help! Do you have a good suggestion for bench lighting that doesnt have THIS problem? w2aew 2022-05-16 | I found the unexpected source of bursted noise on my bench - from my under-shelf lighting strip! Do you have a better suggestion that isn't so electrically noisy? Please let me know in the comments, but don't post full URLs, Youtube won't post comments with URLs in them...
#353: Quick Tips: Using a Transistor Curve Tracer as an Octopus I/V Tracer or Huntron Tracker w2aew 2022-04-25 | This short video shows how to setup a full-blown transistor curve tracer such as the Tektronix 576 to perform the same function as an Octopus I/V Curve Tracer or Huntron Tracker. If you're not familiar with the Octopus, check out video #49 here:youtu.be/Gwo3pEH7hUETo learn more about the 576, check out this video:youtu.be/c-y8UmoHbtw
#352: The ULTIMATE Electrical Engineers Toolkit: Analog Designers Edition w2aew 2022-04-01 | In this "special" video, we take an exclusive world-premier look into the ULTIMATE Electrical Engineers Toolkit - the Analog Designer's Edition!qsl.net/w2aew/toolkit.html
#351: Quick Tip: Cheap source of test sockets wire and for your projects and component test needs w2aew 2022-03-13 | Old scrap VCRs, CD players, etc., especially from the 80s/90s etc. can be a great source for good quality light gauge hookup wire, coaxial/shielded wire, and small plugs/sockets which can be handy for your electronics projects and testing needs.
#350: Adding AGC (automatic gain control) to my QCX+ CW Transceiver kit w2aew 2022-03-10 | Bench project - adding an AGC function to the QRP-Labs QCX CW Transceiver. We take a look at the QCX circuit to see where the AGC will be applied and review the AGC circuit itself. We take a listen to the receiver without the AGC installed, and then again after it is installed. For more information, see the links below:QRP-Labs website - great amateur radio kits including QCX:qrp-labs.comHere are a few of the QCX kits available:qrp-labs.com/qcxp.htmlqrp-labs.com/qcxmini.html...and the link to the ACG module:qrp-labs.com/agc.html
#349: Club Presentation: Smith Charts - the NanoVNA and your antenna - matching network design w2aew 2022-02-24 | This is a recording of a presentation given (via Zoom) to the W6SD San Fernando Valley Amateur Radio Club on 18 Feb 2020. It is a combination of several videos that I've done in the past - including an introduction to Smith charts, using the NanoVNA (and Smith charts) to look at the impedance and SWR of your antenna system and matching network, with a bit of "extra credit" showing L-Network design using the Smith chart. Enjoy!
#348: Quick Tip: What is a connector saver? w2aew 2022-02-20 | A *very* short quick tip video that introduces what an RF "connector saver" is, and what it's used for.
#347: Quick test of the 40m Halfwave End-Fed antenna using a 49:1 transformer / UNUN w2aew 2022-02-12 | This is a followup video to #344 where I assembled the 49:1 UNUN kit from HF-Kits / ARRL. Here I show finalizing the antenna, getting it in the air, and running an SWR sweep on it. Here is a link to the 49:1 kit I used:youtu.be/7XUWOSy_CVE
#346: Basics of Capacitor Leakage / using the Antique Wireless Association DC Leakage Tester w2aew 2022-01-24 | This video discusses the basics of capacitor leakage, and how to test for it - focusing on the DC Leakage Tester available as a circuit board from the Antique Wireless Association. Here are the links for this video:Antique Wireless Association DC Leakage Tester PCB:antiquewireless.org/homepage/pcb-item-4Some good info on old electrolytic capacitors:http://conradhoffman.com/capchecktut.htmRadioWild's Youtube Channel: youtube.com/radiowildNotes from this video:http://www.qsl.net/w2aew/youtube/Capacitor_Leakage.pdf
#345: Generating AM and DSB-SC with a Double-Balanced Diode Ring Mixer / Modulator w2aew 2021-12-29 | This video answers the viewer question I received about how to generate AM (Amplitude Modulation) using a double-balanced diode ring mixer - in other words, how to use it as an AM Modulator. The question arose from three other videos:Basics of Diode Ring Mixers:youtu.be/junuEwmQVQ8Basics of the Gilbert Cell:youtu.be/7nmmb0pqTU0Generating DSB-SC and AM with a Gilbert Cell:youtu.be/38OQub2Vi2QVideo Notes:http://www.qsl.net/w2aew/youtube/DSB-SC_AM_DBMixer.pdf
#344: ARRL 49:1 End Fed Halfwave UNUN transformer kit from HFKits - Build and quick bench test w2aew 2021-12-26 | Today's video features the ARRL EFHW Antenna Kit by HFKits.com, which is essentially a nice, weatherized 49:1 UNUN Transformer to convert the 2500-3000 ohm end-fed halfwave feedpoint impedance down to approximately 50 ohms. I review how to build/assemble the unit, and run a quick bench test.The kit is available from the ARRL as well as HFKits. Here are a few links:ARRL:Sale page:http://www.arrl.org/shop/End-Fed-Half-Wave-Antenna-Kit-for-10-15-20-40-MetersInstructions:http://www.arrl.org/end-fed-half-wave-antenna-kitHFKits.com pages:hfkits.com/build-instruction-impedance-transformer-250w-for-end-fed-antennashfkits.com/product/end-fed-impedance-transformer-250w-diy-kit
#343: Ham Tip: Using the memory feature on a RigExpert Antenna Analyzer AA-55 ZOOM w2aew 2021-12-09 | This short video is a demonstration on how to use the memory / storage feature on the RigExpert AA-series of antenna analyzers. A AA-55 ZOOM is used in this example.
#342: Mini review: County Comm GP-7 / SSB handheld AM/FM/SW/SSB/CW Receiver w2aew 2021-11-27 | Contents:00:00 Introduction00:59 Overview of improvements over GP-5/SSB01:57 Weight, Battery and Volume Control differences03:57 Lets try out some features: Shortwave reception example04:08 Band Selection Controls04:47 Ham Radio Band Selection05:04 Tuning Controls and Step Size 05:52 Auto-scan in VFO Mode06:18 Direct Frequency Entry06:53 Ham Radio goodies - step size and filter bandwidth07:17 Filter BW example on CW08:46 View filter BW using FFT on an oscilloscope10:29 SSB Reception example on 40m band10:50 Available filter bandwidths by band/mode11:16 Regular Memory/Preset operation and Auto Tuning Storage (ATS)13:20 Enhanced Tuning Mode (ETM) operation16:47 What's in the box17:11 Optional Accessories17:40 ClosingShort video review and demonstration of the new County Comm GP-7 / SSB handheld receiver. This unit operates on Longwave (LW), Medium Wave (MW - AM broadcast), Shortwave (SW), HF Ham Radio (AM/SSB/CW) as well as FM Broadcast bands. Some really great features and improvements over the previously reviewed GP-5/SSB (see links below) - including direct frequency entry, multiple receiver bandwidth selections, enhanced scanning and memory modes and much more. Here are the links to my videos on the GP-5/SSB, as well as a link to the County Comm website for the new GP-7/SSB:GP-5/SSB Review: youtube.com/watch?v=JuEPJ3qGu_gGP-5/SSB Memory operation: youtube.com/watch?v=9THTspBkFg0CountyComm webpage on the new GP-7/SSB:countycomm.com/products/countycomm-gp-5-ssb-general-purpose-radio
#341: Ham tip: Safely using a coax switch to connect multiple rigs to a single antenna system w2aew 2021-10-31 | This video answers the question - "Can an antenna switch be used in reverse, to switch multiple radios into a single antenna system and, is it safe?" The answer is - YES, in most cases - as long as the switch grounds the unused inputs, which is usually the case. The video takes a look at the numbers, describes how much isolation is needed, and then shows how to measure the isolation using a NanoVNA, and finally shows the results using a couple of HF radios. Notes from this video are here: qsl.net/w2aew/youtube/coax_switch_isolation.pdf
#340: So, this thing happened today... :-) w2aew 2021-10-22 | Very honored to have earned this Silver Creator Award from YouTube! Of course this wouldn't be possible with the more than 157,000 subscribers that have contributed to nearly 20 million views of my videos. I humbly thank you for your support over the years!
#339: Basics of a Super-heterodyne Receiver - how it works, and a peek at the signals w2aew 2021-10-14 | This video presents the basics of the superheterodyne receiver, and the function of each of the blocks. The operation of the frequency conversion in the mixer and the job of the IF filtering stage are described and demonstrated on an actual radio. I use an old Realistic DX-160 shortwave receiver as an example, and show the spectral content of the RF input, the local oscillator (LO) to the mixer, the spectrally inverted output of the mixer, and how tuning the VFO / main tuning knob of the radio adjusts the LO frequency and determines which input signal lands in the IF bandpass filter to be demodulated.As mentioned, here is a link to the basics of mixers and frequency conversion:youtube.com/watch?v=Mm7WfVzr1aoVideo Notes:http://www.qsl.net/w2aew/youtube/Superhet_Receiver.pdf
#338: Probe Tips: Beware of capacitive loading of oscilloscope probes on your circuit operation w2aew 2021-10-06 | The capacitive loading of your oscilloscope probe might affect the operation of your circuit - certainly something to keep in mind when probing around. The test circuit used in this video is shown at 11:08 in this video:youtube.com/watch?v=G9zZRNzhsEE&t=668s...and I'm probing across Cs in the lower left corner of the schematic.1X passive probe can have 100pF or more of capacitive loading which can dramatically affect many circuits. 10X probes are typically 8-15pF or so, with some exceptions. Active FET probes offer very low capacitive loading, typically under 1pF.
#337: Use a NanoVNA to measure input impedance and gain of a small-signal RF amplifier w2aew 2021-07-18 | This video shows how to measure the input impedance and gain of a small-signal RF amplifier - including the use of an attenuator to keep the amp in it's linear range and also to not overdrive the NanoVNA. This stems from a recent conversation with Bill N0CQR (SolderSmoke podcast). The amplifier featured is a "Termination Insensitive Amplifier" or TIA that is described in paper by Wes Hayward (W7ZOI) and Bob Kopski (K3NHI) - see links below:Soldersmoke blog:http://soldersmoke.blogspot.comWes's webpage: w7zoi.netThe TIA paper: http://w7zoi.net/bidirectional_matched_amplifier.pdfPapers on the theory and models of transistor amps:http://w7zoi.net/fba_with_simple_model.pdfhttp://w7zoi.net/transistor_models_and_the_fba.pdf
