TSP #34 - Teardown, Analysis & Repair of an Agilent E4407B 26.5GHz ESA-E Spectrum Analyzer

In this episode Shahriar takes a detailed look at an Agilent (Keysight) E4407B ESA-E Spectrum Analyzer. The instruments reports an “Unlock LO” error message which prevents internal alignments from being performed. Before the repair process can begin, the firmware of the instrument must be updated. The firmware upgrade requires the installation of additional flash memory ICs which is presented in the video. The main processor board with its various components are also described in the video.
The complete block diagram of the spectrum analyzer is presented with a detailed look at the principle of operation of the instrument. All the main functional blocks such as the YIG Oscillator, Phase Detector, LO Path, LO Amplifier, Charge Pump, Pre-tune segments, digital circuits, IF and LO paths are analyzed both in schematic and on the PCB. Several potential faults are investigated and measured.
The Signal Path
www.TheSignalPa...

[@1337NoMad1337]

I just watched the whole thing. Please keep your videos as detailed as they are. I'd rather watch one 2h video than 8 15m videos that don't even scratch the surface on technical details. Digging deep down into the matter and explaining how one thing matters for the rest of the system, how it works and comparing your (concluded) expectations to the real world data - thats what makes your videos enjoyable as well as educational.

[@1337NoMad1337]

Also, I would really like to see a video on those Black Magic RF PCB Paths. Especially how their shape contributes to what effects they have.

[@droelfdroelfify]

100% agreed. Every serious technophile likes the show to be this detailed. Thumbs up :)

[@MrLRankin2]

@@1337NoMad1337 Me too.

[@campbellmorrison8540]

@@droelfdroelfify Totally agree, wonderful to see the mind of an expert working

[@mjthebest7294]

This was pure gold. Oh my God! I know it's been 5 years, but I wanna thank you very much for all the precious informations and thought process contained in your videos. I'm slowly watching every single video in order from the first one, and I have to say this is one of the most underrated channels I ever encountered. You are also a very kind person to share your knowledge with everyone interested. Just wow, you sir are inspiring me so much.

[@RALL123456]

7y later, i want to second everything you said! Definetly underrated!

[@hambrew]

I'm watching this 9y later and like the amount of detail in one video.. I like the one video rather than broken into N and golden nuggets lost in editing. What is a golden nugget to one might be interpreted as comon knowledge to others.. Longer videos, less cutting (8

[@markbowers2053]

I realize I’m 9 years late in this watch, but I have watched quite a few of your other posts. They are always informative and extremely well done! I’m a retired RF engineer and am amazed at your knowledge level and experience. I always learn something new. Thanks for all the time and effort you obviously put into these!

[@MrLRankin2]

Bored! Are you kidding? The explanation was priceless.

[@jebsaekam]

Fantastic! Don't change a thing for your repair videos, they are very well done.

[@DantalionNl]

cant agree more, already to many channels which just breefly go trough a repair video. This format with al these amazing details and explenations is way beter!

[@superdau]

I watched to the end. First hint: don't apologize how long the video will be all the time ;) . I guess most people, who watch your videos, know what they are getting into and are watching them for exactly that reason. There are enough "simple" electronic videos out there already. And a few of the bigger channels that shall be unnamed unfortunately have gone that way. Admittedly I had to plan when I watch a 2h video, but in the end it works well with dinner and desert ;) .

[@ryansoh333]

I just wanted to say thanks for all your efforts. The videos that you make are not only educational but also quite entertaining. -- EE student.

[@toastedcrumpets]

I know I'm over 5 years late, but my answer is that the harmonics of the first mixer gives an output Intermediate Frequency (IF) which is IF= RF±k*LO, where k is an integer. As we want to sweep RF frequencies at the same speed but are using higher harmonics to downconvert further, the speed of the LO frequency change must scale as 1/k. So the first slope is D, the second slope is D/2, third slope is D/3 etc. Great video, still working my way through all of them. You've taught me RF electronics!

[@topherteardowns4679]

If anyone stopped watching, they are unworthy of your videos. Repair videos like this are brilliantly captivating. I couldn't stop watching it. Thank you for devoting your time to do this!

[@andrewmcneil]

Had this playing while I was working on the bench needless to say I did not get any work done. Big thumbs up when you’re watching something this interesting you don’t notice the time!

[@robmacl7]

Nice video! Not a microwave guy, but I do know about opamp integrators. The OP37 has reverse parallel protection diodes on the +/- in to prevent avalanching the EB junctions, which is common in precision bipolar opamps. This is why the reference voltage at the PLL integrator was changing even though the opamp was good. The inverting input signal was dragging the noninverting input because the overall feedback loop was open. The opamp output banging between the rails is a symptom of the overall loop being open. The OP27/OP37 are a pretty standard low noise opamp with multiple sources, and may be used even when the bandwidth is not needed. I think what is more important here is the very low 1/f noise (10 Hz 1/f corner), not the ~ 3 nV/rtHz spot noise. 1/f noise in the PLL loop is going to create close-in phase noise. The wide bandwidth of low noise opamps is kind of a side-effect of running the input stage at high current to minimize the noise. The two pole-zero pairs in the error integrator would be compensation for the entire PLL feedback loop. If something else in the loop starts to roll off then you would have an unstable two-pole rolloff, so you add a zero to the integrator to cancel this.

[@DriverEntry-p7q]

Rob, I'm late to the party. I kept thinking why the input jumps and came to the similar conclusion. After watching the video again and scrolled through the comments and saw your comment which confirmed my guess. I saved your comment. Thank you!!!

[@Tjousk]

1:26:46 "There's so many things!" Indeed, thanks for showing this much detail.

[@Tjousk]

And now watched to the end (:

[@TheBreadboardca]

Awesome video, watched it through to the end, loved it, very educational and very impressed with the repair

[@WhitentonMike]

Watched all the way through. Set the playback speed to 2X for about 90 minutes. Great coverage of the overview and specifics. No problem on the length IMO because everyone has the choice to skip ahead if they wish. Those that need the high detail have that option as well. Best of both worlds. If you edited it down to 30 minutes for example most of the operational discussion would be unavailable. Better to leave it in again IMO.Thank you however for not making us watch you wait days for parts to arrive. ;)

[@MathiasJohanssonBjorn]

Yes! I watch it till the end!

[@BassaliskVFX]

WORTH.EVERY.MINUTE. I cannot express how much i appreciate your will to share this knowledge with us. Knowledge is a really weak word for what this is.

[@alextrofimov7947]

The tweezers set is gorgeous! :-D Pliers too! And screwdrivers are just insane) I would love to see a tutorial on microwave PCBs and PLLs! No, you are not going into too much detail at all! Sometimes I even wanted to hear more) I really appreciate all the effort that was gone into such a video! OP37's noninverting input did some weird stuff because it's inverting input did some weird stuff. The op amp's input differential voltage is 0.7 V maximum, so if it's more the input protection diodes become open and the inputs start to conduct current - they are not high impedance anymore. If I was really looking and not counting birds looking throuh the window, the part you replaced was indeed making signal on the inverting input of OP37. I had such problem in a product not so long ago, and spent a lot of time, figuring out this bastard, let me tell you. :-) And it turned out that simple)

[@bb-andersenaccount9216]

it is like a sir arthur conan doyle plot. you playing holmes, tracking the hidden clues, and your cat playing watson estimulating your lateral thinking to come up witj a clever resolution of the case. really entertaining and educational!

[@richardj163]

The long video helps me understand the background wizardry of how you troubleshoot.

[@jjoster]

Informative and enjoyable. Length was not an issue. I'm glad you waited for all the shipments of parts to arrive so the entire story could be told in one go. Great job. Now, lets do that PLL video!

[@jon_collins]

7 or 8 years later, just watched the whole thing, this is valuable knowledge.

[@dop3j0e]

I just rewatched this in its entirety, for the third time I believe. This is easily my favorite TSP, please never succumb to the allure of mass compatibility and keep taking us down the rabbit hole with you :)

[@DannyBokma]

On your remark; I watched the whole video! Although I skip parts once in a while when things are confirmed/told double. I noticed that the OP37 has two anti-parallel diodes on its + and - inputs, this might be why you saw the output of the opamp back on its input. All in all I liked the repair video a lot! Respect and thanks for you videotaping and editing it all!

[@youpattube1]

One of your best. It is detective work at high speed. I look forward to the next non-trivial repair.

[@flaviaduna]

I did not have the time to watch it all in one piece, but that did not stop me to see it until the end. There is no problem with long videos as long as they are interesting, this one was and so were most of them. Keep the level up because these kind of videos are so rare.

[@0PAIx]

Very interesting following the plot from start to end. I look forward to your videos and eat up the demonstrations to illustrate the theory that normally precedes the practical section. I'm particularly impressed at your acquire and repair programme that is filling up your lab with some very impressive kit at knock down prices. Keep up the good work. Very pleased at your recent volume of output, it has been well worth the wait while you were otherwise engaged elsewhere. I'm a keen viewer.

[@GeoffreyThornton-TheWinGuru]

I know this is an older video, but I really appreciate the level of detail you included in each step of your assessment and troubleshooting. A lot of the theory of operation is beyond me, but I nonetheless appreciate how you narrate your thought process and how you go from block to block, ensuring proper operation before moving on. I'm really glad you were able to fully repair this device in the end and I don't mind at all the length. It's great to see everything contained in one video and I enjoy all the technical aspects, even if they are a bit foreign to me. Between your videos and Mr. Carlson's lab, I get both classic and modern electronic design and troubleshooting ;-)

[@TheExcessiveDose]

Again, a great video! I really do like the long block diagram and schematic parts because this is from what i learn the most. And I'm really looking forward to your PLL video. :-) PS: The reason the oscillator sweeps at different speeds is beacause it is multiplied by different factors while the instrument scans over it's full measuremnt bandwidth. When the oscillators frequency is multiplied by a higher factor the oscillators scan speed has to be lower by this factor to get the same scan speed at the resulting measurement frequency.

[@fpliuzzi]

Thank you for this two hour troubleshooting/repair master class. It was extremely interesting.

[@AI7KTD]

Thank you for all the time and attention you put in these videos. It's 2:33AM and I just finished watching your two hour long repair!

[@ResearchAdvantage]

Like the several commenters below--from 7 years past--I just finished the two-hour video and 'copy and paste' their remarks here as well. Not only are the long videos most informing, they hold their relevance very well over time. I have found from experience that there is no better way to learn a skill than to watch a complex repair done by someone who knows what they are about. I have followed your progress over the years and any advice I might post here has been implemented, so just keep doing what you do so well.

[@KeenanTims]

Epic video, watched to the end and enjoyed it all. Keep doing the deep technical dives and resist the urge to cater to the LCD. I always learn a lot from your videos, and they are presented well enough that if less knowledgable folks are watching them, they probably pick up lots of interesting bits too. And I'd love to see that video on PLL design.

[@AnonyDave]

Maybe I have too much spare time, but you never have to worry about going into too much detail. All your videos tend to be extremely interesting and well presented. I always learn something new in each one. Keep up the great work!

[@fdesmet]

I watched it all and was mesmerized by the whole thing. And I'm just a software guy. Fantastic!

[@TheElectronicDilettante]

Talk about tool envy…. That set of tweezers is Awesome! Great video. The longer, the better. The more in-depth, the better. You have have a tremendous amount of knowledge and experience to convey, and it’s not gonna get done watching the clock. For those viewers with no attention span, there are still Shorts. Cater to highest common denominator. Thanks for the video(s)!!

[@wisehart77]

All your videos are great. But this one was exceptional. Following along with your thought process was very interesting and educational. I would love to see more like this. Fantastic! Thank you very much!

[@RupertHandford]

Watched every second. Very interesting and educational as always. Love your videos and explanations, would like to see one on PLL's. If I knew a fraction of what you have probably forgotten I would consider myself a lucky man. Keep up the excellent work!

[@wither8]

Great episode! No such thing as too much detail. Go into the PLL details when you get a chance. Coming from a CS/math background, it's interesting to the similarities between the mental frameworks of our approaches to diagnosing problems. You should do more tutorials for people like me (CS guys who got interested in EE in their mid 20s ater uni, especially since the cost of gear/fab'ing is real cheap.) Your tutorial on data transmission was real interesting and you have a great way of teaching via practicals, like Dave Jones on the EEVblog. Keep it up & more tutorials!

[@octavmandru9219]

Your explanations are not only welcomed but very important to us. Keep it up and thank you for the chance we get to get a glimpse into these amazing instruments. Oh, watched it till the end, breathtaken

[@glenwoofit]

Great video! It's 1 am here now but I couldn't switch off. I really like the thought process on camera while fixing complex devices.

[@witeshade]

Just got done watching it all, it's really fascinating. I for one love all the detail you go into; these machines are so complicated, a lot of times people gloss over the details so much that it still looks like a magic box. Digging into it feels far more educational, and makes all the various parts make a lot more sense.

[@nheng6913]

Watched the whole thing. Great job and an inspiration to those almost brave enough to tackle a similar project. Glad to see that the Hitite (ADI) part is still in stock :) About to tackle an MS2721B with LO1 after watching your videos.

[@risagian]

Your videos are better than National Geographic documentaries, it has been 2 days that I'm watching, really professional, congratulation !

[@adrianschneider4441]

Yes please stick to this style of long and elaborate video. They are outstanding, I enjoy them a lot with all the detail and way of reasoning and trouble shooting. Interesting to learn something about the more complex type of equipment and hoe it works.

[@n6gnSWTL]

As the designer of the board on the other side with the references and later IFs ( that still worked!), I have to say that I enjoyed your presentation and watched the entire 2 hours. It's been >20 years since I worked on that project or even for HP (I left the company the month it became fully separate as Agilent, but it brought back a lot of memories. Thanks.

[@jimmc4929]

Nice work. Please don't think others don't appreciate all this technical detail.

[@graemelaubach3106]

Another spectacular video! I love watching how excited you get while investigating a new circuit board, it's infectious.

[@ruhnet]

Watched start to finish. Learned a lot. Thanks so much for taking the time to share your knowledge!

[@AxelWerner]

i watched it until the end. VERY INTERESTING how you track down the problems and fix the problems . it looks easy..but i see that it could not be done with simple 200mhz mdo and a multimeter ;) - also the replacing the tiny smd chips from masse production pcbs to me is a pain in the ass. - maybe it would be an interesting topic for another video of yours to show us how you desolder some of those chips and what are the tricks to not damage nearby components, but safely and non-destructive you can remove a component like that lil chip. - keep up the good work. its very educative and interesting. thanks!!!

[@mopar3502001]

Excellent video! I prefer the lengthier videos myself, and would love seeing more videos of this size and depth. Great job!

[@emusan]

Just watched through the whole thing! Great video! I really enjoyed all of the detail you had in the video and I wouldn't mind at all if you continue making longer videos like this. I also liked to see your process for finding the cause of the issue, narrowing it down and eventually getting everything fixed. Keep up the great work!

[@egbertgroot2737]

My whole morning schedule disrupted by started to watch this video. One of the most interesting i ever watched. Worth the time spent! thnx

[@musicmakelightning]

Watched the whole thing. Really enjoy your thought process. Very important training for the student! Thanks!

[@ChrisGJohnson]

Another superlative video, and well worth the two hours. This kind of detailed investigation is what makes the signal path videos great. I'd definitely enjoy a PLLs video in future.

[@AlexBlate]

I'm loving it! +1 for technical detail and your great explanations. You have, by far, the best technical, educational KZbin channel in this space. My only complaint is that you don't post more often :) Thanks again, Professor!

[@mariocordina5262]

Great video indeed!! The tutorial/teardown/repair mix is awesome and I would love to see more of this in the future. What about starting out an RF tutorial sessions and dedicated a full session on say VCOs, PLL, DDS, Filtering etc.. Starting from the theory and basic building blocks and proceeding to the implementation and testing of such blocks. One might also look into RF PCB design (microstrip lines etc.). Would be great to have a paced approach on such topics - albeit must admit it would take you a lot of your precious time to prepare/deliver this!

[@smunaut]

Yeah, watched it to the end :) Very interesting stuff ! The change in the sweep rate of the YIG is obviously when scanning the various harmonics of the subharmonic mixer. I'm actually working myself trying to fix a E4433B siggen that has an unlevel output. Unfortunately I can't find a replacement output board, it's also full of agilent specific parts and I also can't find schematics (only block diagrams).

[@rfsniffer3175]

Great video on a spectrum analyzer. There can never be enough details to engineers who want to learn.

[@DaviixiitOh]

Hi, you know how I could read Unit C: From the analyzer on my computer? :)

[@LdHrothgar]

The block diagram section almost put me to sleep (to be fair, it was just after lunch so I was already primed to want to sleep anyhow!) but the rest of it is gold, I love seeing this stuff tested and repaired! Great video, I love this youtube channel.

[@adamalterman6657]

I'm a neophyte to all of this, but it sure pushes the limit for me. I did watch this to the end. I like to repair electronic stuff though I have no formal training. This video instills confidence that all the time I spend with trial and error testing is not for naught. I do appreciate that you get to the point and don't repeat yourself or waste my time. I find your knowledge impressive. keep it up with all the detail. Adam M. Alterman, MD

[@bentsignpost]

Watched it to the end, didn't understand the majority of it, but loved it. Another fix. Good, educational stuff.

[@kl1nk0r]

Shahriar, I have to say this was one of the most... thrilling repair videos that I have ever seen on KZbin :-D I watched it to the end, without a break. It was also very pleasant to watch, because you explain in very good detail what you are doing and why. This is, what I often miss in other peoples videos. There is much to learn here! And btw, Somewhere in the middle of the video I already guessed it had something to do with the divider chain, I don't know why. Maybe because those jumps in the Tune Voltage were occuring in each of the sweeps at exactly the same voltage points.

[@totbenru]

A Master Class. I watched every second of it, and will watch it again. Long and detailed videos are good!

[@rickeymh]

Shahriar- Thank you for posting this video. I have not worked with RF on a board level for over 20 years and your analysis brought back a lot of technology I had forgotten.

[@Richardincancale]

Great way to spend a Sunday afternoon watching on a large screen. Just the right length!

[@absolutecharles]

I'm glad you made a longer video like this. It is obvious that you still edited out things like undoing the fasteners, so it is 2 hours of real content. There are probably people like me who will skim this video at first, and then go back to it when they are in the right mindset to absorb the whole thing. I think it is valuable, thank you.

[@AndySpicer]

I just watched this to the end. For the second time! Never boring, always learn stuff. I’m sure I’ll watch again a couple years down the road!

[@WesQ4521]

Watched it! Great video. Not every video should be this long, but it is nice to watch more comprehensive videos once in a while.

[@lambertax]

Never give up. And here is the result. When I think I'm watching this awesome video in 2021! Still so useful and not bored at all...

[@OldePhart]

Watched it to the end! Your enthusiasm makes it easy to do. :) I'd like to see something on the way PCB layout becomes passive components. Like the splitter combiner loops you showed and the stops. I'd like to grasp how that works.

[@riosamaria]

love your videos, i look forward to new ones.THANK YOU!

[@Tyradius]

That was... Awesome! I've been looking for detailed repair videos like this. It really helps to see the diagnostics approach and the fix. I've seen a few other guys attempt repairs, but they usually give up after a short while. While you can see some of the diagnostics process from them, its not as complete, nor as rewarding as seeing it all the way through. Keep up the brilliant work!

[@matthewgrimsley4506]

I really enjoy the long videos with detailed explanations. Although, your truncation rounding, reading 4.89__ as 4.8, makes my brain itch.

[@andymouse]

Still listening !!! 9 Years later !!! should be required reading....cheers.

[@nicholasbantell2520]

It required three sittings to watch it all but I really enjoyed it and learned from it. It may have been a bit long but well worth it.

[@jonka1]

Be assured that you long explanations are pure joy to listen to. Please keep enriching your videos with them.

[@Thesignalpath]

Thank you!

[@DaveCurran]

Well I watched to the end. Interesting stuff. RF still seems a bit like magic to me, especially the PCB traces that looked the Commodore logo.

[@ggattsr]

Loved every minute/hour of your video. Don't change a thing. Hopefully you will do one on PLL's.

[@dalebrooks6816]

I know this is an older video but fantastic job troubleshooting. I just purchased a spectrum analyzer and it has front end problems that will have to be repaired. This will give me more confidence in tackling this equipment. Thanks for the great video! Yes I watched the whole video and glad I did.

[@allroundenthusiast5126]

Amazing work and amazing video, I watched it to the end. Walking through the schematics and pcb layout was inspiring. As for the puzzle, no one seems to have solved it yet, so here's my take on it: As the spectrum analyzer uses subharmonics to get above the actual oscillator range of 3-8 GHz, the sweep is split in 4 parts, each with their own multiplier - which multiplies not only the frequency, but the rate of change of the frequency (i.e. the effective sweep speed up to 26.5 GHz) as well. So to keep the effective sweep speed within acceptable limits (needed to get roughly the same resolution across the whole bandwidth) you have to lower the speed. Looking at your measurements, the sweep speeds seem to be in ratio's 1:1:2:4. The first is probably to probe the low range, the three sweeps following are for approximately 3-8 GHz / 6-16 GHz / 12-32 GHz.

[@pewfall2052]

Irrespective of the length of the video this is the best yet. It shows your enthusiasm for the subject. This was way beyond my knowledge but I watched it all. It shows you are a talented teacher.

[@jimm2099]

Shahriar, I watched it straight through to the end with a few short pauses. Fantastic video! Over the years I've also collected several HP/Agilent/Tektronix instruments, some I've repaired and some I haven't needed to. Their build quality and documentation is second to none. You obviously have a much better knowledge of RF than I and I really like the detail you provide. It's a learning experience for me watching you videos. Thanks very much! Jim

[@OctavMandru]

I watch it front to back every time it comes in my feed, I think it's the third time already. Good news is that I feel I understand more each time. Thank you for your sharing your knowledge, that's how humanity's average brain can grow Since I can't find any answer to your question, here's my 5c: The sweep speed changes because the instrument uses the YIG to sweep two different ranges of f. I know I am 8-9y late with my answer, but keep in mind that my interest in EE barely sparked 7-8y ago, so to get a glance at your level took me a while.

[@yaghiyahbrenner8902]

Thank you Shahriar! 2hrs of goodness. much appreciated.

[@sirousmohseni4]

Watched it all the way to the end. Grate job explaining the details and thought process and approach in your work.

[@patmx5]

Very fascinating and thorough video, Shahriar. 6+ years later I'm quite late to the party, but just watched the entire thing and was riveted. Appreciate the clear explanations and analysis, and the chance to follow along with your troubleshooting methods.

[@thisoldguy]

Excellent video, and I watched it to the end as well! I really appreciate the equipment repairs and the amount of detail you go into. It really is informative. Please keep the videos coming!

[@crabxcorelol69]

It took me a couple days to complete the video, but let me just say that was great! I feel like I learn so much by watching your videos. Keep it up!

[@GregorOttmann]

I loved this video, just like I loved almost every other one you made. I don't think it's too long or too detailed. Quite the opposite, actually - I enjoy long videos like this as long as the content is interesting. I'd actually even appreciate some more details regarding the things you do. The best example is the removal of that opamp. I'd really have loved to see how you did that.

[@farahboussari]

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[@kevy1yt]

Watched till end and was rewarded by a successful repair. Very nice work!

[@MrRealisticMan]

Awesome !! Worth watching all 122 minutes. I really appreciated the way You explain all the schematic and split it in separate working parts of the unit and explanation on the function of each section.Nice to know some parts are available even they are not in stock at HP/Agilent/Keysight any longer.

[@ytrewq6789]

Thanks Shahriar, I just acquired this model Spectrum Analyser from a lab that was going to throw it out because of this exact problem about three weeks ago . Thanks to your work and this video I was able to fix it today after watching this becausen of an already on hand replacement part after being stumped for the whole time...... Thanks again and cheers from a fellow Canadian with a now working Analyser, Thanks to you :-)

[@salat]

Wee.. it's now 3:56 AM and I'm through the whole video - Glad that it's a holiday here today, going to bed now - thanks for this detailed repair :)

[@emcgon]

I watched it all the way through and enjoyed every minute of it.

[@WTK444]

Watched to the end. I like the amount of detail - it's one reason why I find your channel to be so interesting.

[@harbselectronicslab3551]

I actually have these running in the big screen in my Lab......I tell you when I am working late at night these video's help me make it through every time......you good blokes on KZbin are my coffee hit lol

[@franciscgedeon9237]

Yep, watched till the end. Very interesting work, I like it how you feel so confident around tens of gigahertz.

[@smgvbest]

I've watched this several times now, all the way thru each time and wow. This is the type of repairs I've been looking for. The length is not an issue at all. The detail is fantastic. I hope you'll do more like this with the deep technical dive into the block diagrams and the schematics. As a learning tool seeing the practical, real analysis as you go thru it help so much in expanding my knowledge. Then seeing all of it come together in the repair was great. I'm not a engineer (though my title does contain that word). I do electronics because It fascinates me and I enjoy it. To me this is 2 of the best hours on youtube.

[@terrysouthwood4757]

Fantastic detail. I watched all of it and enjoyed following your train of thought. More please.

[@BobMellor1954]

Fantastic video, the descriptions were easily understood and were to the point. Yes it was a long video, but very educational and enjoyable. Thank you for sharing.