50 - LC Matching Networks - Part 1

[@johnwest7993]

Thanks Nick! The most important part of what you're explaining isn't what you're doing, or how you're doing it, but WHY you're doing it, and you do a great job of that. A machine can be designed to know what to do and how to do it, but it takes a person to know why.

[@M0NTVHomebrewing]

Thank you so much John. I remember looking at this stuff some time ago and thinking it was just too much maths to bother with. But actually, once you understand what it is you are doing then it is not half as bad as you think it's going to be. Thanks again. 73, Nick

[@petebryson446]

11:48

[@johnnybigpotato2404]

Amazing! Should be mandatory to watch this video. ;) Looking forward to part 2! :)

[@M0NTVHomebrewing]

Thanks very much Johnny! Glad it was useful. 73

[@InteraliaTony]

Every day a learning day when you watch one of Nick's videos.

[@M0NTVHomebrewing]

Thanks so much Tony! Hope you are doing OK. Have a good weekend. 73, Nick

[@alanmacdonald65]

Always a treat to be learning something from you on a Saturday morning my friend! great explanations as always.

[@M0NTVHomebrewing]

Thanks so much Al. It's all your fault of course ... clearly you taught me too well! Have a great Easter weekend and let's meet up for pint soon :)

[@gradje74]

Again an excellent video, valuable and highly appreciated. The importance of impedance matching already became clear in the “Connecting It All Together” video I watched a couple of days ago. I skipped it at the time you published it because I thought, reading the title, it was not important to me. Apart from the electronics lessons, your pronunciation is a pleasure to hear, most Dutchmen do not exceed the level of a football coach. 😆 Thanks a million 73, Gerard

[@M0NTVHomebrewing]

Thank you so much Gerard. That's very kind of you to say. Glad you are finding the videos helpful. 73, Nick

[@hygri]

Nice, firmly subscribed! Great explantion, the logical flow doesn't miss a beat - can't wait for part 2

[@M0NTVHomebrewing]

Thank you very much. Glad you found it helpful. 73, Nick

[@monteceitomoocher]

Many thanks, I'm just here packing some circuit theory and am new to rf design, you're one of the few people who actually makes electronics understandable and interesting even to my old brain!, I'm subscribed.

[@M0NTVHomebrewing]

Thank you very much - and for subscribing too! Welcome to the channel. 73, Nick

[@gasturbine101]

Brilliant work fine business old man!

[@M0NTVHomebrewing]

Thanks very much. Best wishes, Nick

[@Platon_28]

Well done, Nick, congratulations. We look forward to the next video. 73

[@M0NTVHomebrewing]

Thanks very much. 73, Nick

[@jlog7395]

Brilliant explanation Nick. Worked around this for years but now I have the fundamentals of impedance matching. Happy Easter.

[@M0NTVHomebrewing]

Thank you very much. Yes, me too - I was always put off by the maths but its not too tricky if you break it down. Happy Easter to you too. 73, Nick

[@BobMellor1954]

Thanks Nick, great explanations throughout of a very interesting and essential topic and as usual, explained in a clear manner. Happy Easter 73 Bob

[@M0NTVHomebrewing]

Thanks so much as always Bob. Hope you are doing OK. Have a great Easter yourself. 73, Nick

[@M0NTVHomebrewing]

Thanks very much as always Bob. Hope you are doing OK. Have a very Happy Easter yourself. 73, Nick

[@zsradioham]

Thanks for an informative lecture on this subject. Very applicable for the new Ham's and experimenters

[@M0NTVHomebrewing]

Thank you very much indeed. 73, Nick

[@stevekoehn1675]

I like the way you think, or should I say, since physics doesn't care how we think, how you think when explaining electronics.

[@M0NTVHomebrewing]

Thanks very much Steve. 73, Nick

[@acestudioscouk-Ace-G0ACE]

Thanks Nick, well explained as usual and I got the jist. I might have to run it another couple of times to absorb it all. Best 73 Ace

[@M0NTVHomebrewing]

Thanks Ace. I know what you mean! 73, Nick

[@tmmlrd]

Thanks for this very clear explanation, by the way your English speech sounds very understandable to my Italian ears. Subscribed! 73 de IW5CWC

[@M0NTVHomebrewing]

Thank you very much and welcome to the channel! 73, Nick

[@Steve-GM0HUU]

👍Excellent video Nick, thank you. Very well explained and nifty diagrams. Really looking forward to Part 2. In fact, if Part 2 is not posted very soon, I shall be writing to my MP to demand action 😂.

[@M0NTVHomebrewing]

Thanks very much Steve. Glad you found it helpful. Part 2 shouldn't be too far away. 73, Nick

[@LousyPainter]

New subscriber here. Great series. Looking forward to the next video! Thanks.

[@M0NTVHomebrewing]

Thanks very much for watching and for subscribing. Welcome to the channel. 73, Nick

[@RadimPolasek]

great explanation, thanks 👍

[@M0NTVHomebrewing]

Thank you Radim. I'm pleased it was helpful. 73

[@shean4]

Thanks. Excellent presentation.👍

[@M0NTVHomebrewing]

You are welcome! Thanks very much for watching and commenting. 73, Nick

[@TheFretman2]

Very timely...I'm trying to match a QRPp transmitter to a 50ohm load now.

[@M0NTVHomebrewing]

Timely indeed then! All the best in your building.

[@Steve-GM0HUU]

For my latest homebrew QRPp transciever project I also have suspected output to 50 Ohm mismatch problem. At QRPp, every mW is a prisoner 😂. This video shall hopefully help me sort out the matching.

[@ihabsglei]

Thanks for the great explanation. Is that also the procedure when you match a transmitter to an antenna?

[@M0NTVHomebrewing]

Hi there! It is one way to do it - but there is a bit more to it. Stay tuned for part 2! 73, Nick

[@darioj.7454]

Hi Nick, Fantastic explanation! Only I have a conceptual doubt. The maximun power transfer theorem speak regarding the magnitude of transfered power, but not regarding efficiency.When ZL (load)=Zi (gen), it will have the maximun power transfer but only 50% will be dissipated on the load (bad efficiency, only 50%). Now if ZL and Zi have (in example) 4,4 times difference (i.e. 220/50 ohms. or 11,4/50 ohms) VWSR will be 4,4:1, and in consequence 40% of the total power sent to the load will be reflected to the gen, but the efficiency is 60%, then in this case even when we have reflected signal, te power effectively dissipated in the load is 10% greater. Apparently is not this theorem the real reason to match the network. Then my question is: if even when the network is unmatched we get more efficiency than matched, why to match?. PD I know that I must match the network, but I dont have answer to my doubt, :-(

[@M0NTVHomebrewing]

Hi there! Thanks very much. That's a very interesting question! It is one I would have to do some research into before attempting a proper response. However, I think it is about the fact that maximum power transfer and efficiency are two different things. Sometimes (e.g. in an RF power amp) we might sacrifice power output for greater efficiency in a battery operated radio. Sometimes though we might do the opposite - we accept poor efficiency (like class A) so as to have a cleaner output signal. There is an interesting exchange about this here: electronics.stackexchange.com/questions/449645/does-impedance-matching-imply-any-practical-rf-transmitter-must-waste-50-of-e Thanks for your thought-provoking question! 73, Nick

[@gregwmanning]

I am certainly pleased I found your fabulous channel. Did you learn all this RF knowledge from the Experimental Methods in RF Design book you refer to often?

[@M0NTVHomebrewing]

Hi Greg, thanks very much. EMRFD is certainly a great treasure trove of RF information but it is one of many different sources that I use. In the next video I'll signpost a few helpful articles that are freely available. Thanks again. 73, Nick

[@briangeorge3344]

Really helpful video Nick - your presentation skills are first class and make it so much easier to understand these concepts. Would you be able to help with one quick question? Let's suppose we want to match a homebrew CW ladder crystal filter (about 11 MHz and impedance of say 200 ohms) with an MC1350 I.F. amplifier (input impedance of say 2,000 ohms). Should we go for a low pass or high pass impedance matching network? Thanks again Nick and looking forward to Part 2!

[@M0NTVHomebrewing]

Hi Brian, thank you very much for your kind words. I’m not at home at the moment so can’t simulate your precise scenario. However, just off the top of my head: with an impedance transformation ratio of 10:1 and a narrow CW signal in an IF section then either high pass or loss pass should work just fine. This is because you won’t require much bandwidth at all. Hope this helps. Thanks again. 73, Nick

[@JediBuddhist]

Thank you.

[@M0NTVHomebrewing]

You are very welcome. Hope it is useful. 73, Nick

[@tupai776]

Thank you very much 73.

[@M0NTVHomebrewing]

You are welcome! 73, Nick

[@bbigboy01]

Nice presentation. You may at some time in the future introduce the SimSmith program to our audience. 73's.

[@M0NTVHomebrewing]

Thank you. I'm going to get into the dreaded Smith Chart in part 2! I'll have to check out SimSmith. Thanks for the heads up. 73, Nick

[@romanescu_misha]

That was a really good stuff.

[@M0NTVHomebrewing]

Thanks very much Michal. 73, Nick

[@drstrangelove09]

That was excellent! Better than my EE filters course content! Only thing is: your quick aside at the beginning where you showed the resistive network to match 17 Ohms to 50 Ohms -> I do not see how that could work? (you added 33 Ohms?)

[@bazzaar1869]

Yeah, Nick has gone wrong here, his circuit now present 83 ohms to a 17ohm source! The following pi network gets it right, although the labeling is confusing.

[@M0NTVHomebrewing]

Thanks very much. The cheap and dirty resistor trick DOES work actually - but crucially only in one direction (which I didn't say). You and the commenter below are quite correct that the source will see 83Ω but the LOAD LOOKING BACK TOWARDS THE SOURCE WILL SEE 50Ω. If you run it through LTSpice or a Smith Chart calculator you'll see for yourself. Where folk can be tempted to do things like this are for example on the ports of a diode ring mixer. The IF port in particular just wants to 'see' 50Ω. It couldn't care less what the source of the input signal sees. So the mixer port is happy but there will be reflected signal back towards the source because it sees 83Ω. Hope this makes sense. On reflection it perhaps wasn't the best example to give so apologies for any confusion. Thanks for watching as always. 73, Nick

[@M0NTVHomebrewing]

Please see my reply to @drstrangelove09. Thanks very much. 73, Nick

[@bazzaar1869]

@@M0NTVHomebrewing Well now you are just compounding your errors. In your example the cheap and dirty resistor DOESN'T work! Terminating sources correctly IS the prime requisite. Your example source is not matched. You need a parallel resistor to match the 17 ohm source or two resistors to make the match both ways. The impedance back from a resistive load is not important. There are no "reflections" from a pure resistive load only the consideration of meeting either maximum power transfer or voltage drive. Reflections are when you have transmission lines and/or complex impedances involved. Your example of the diode ring mixer doesn't apply because unlike a resistor, a mixer port is a source, and so needs correct termination.

[@M0NTVHomebrewing]

Fair enough. I stand corrected. Thanks for watching and commenting. 73, Nick

[@hoobsgroove]

I want an LC or LCL bandwidth filter hi bandwidth filter for 50 hertz mains running a 220V motor. I want to keep it to 1% but can't really find out through the calculators getting it that accurate tolerance an exactly what type of filtration inductors I really need to get to that level of accuracy or better

[@M0NTVHomebrewing]

Hi there! That's a very specific use case and I'm afraid not one I can advise on. Have you tried asking on some of the more generic electronics forums? All the best, Nick

[@MegaCadr]

Who plays the bass in your intro?

[@M0NTVHomebrewing]

Hi there! It's all me actually. It is three separate lines played on the same bass and overdubbed: the bass line, the riff and the harmonics. After playing guitar for many years the bass is now my weapon of choice! 73, Nick

[@MegaCadr]

@@M0NTVHomebrewing I really enjoy it. The tone and groove is really good. Is it midi drums?

[@M0NTVHomebrewing]

It is actually one of the Virtual Drummers in Logic Pro. Thanks again :)

[@justinelliott3529]

How do we measure the impedance?

[@M0NTVHomebrewing]

Hi Justin, I do tackle this in the video before - No.49. All the best, Nick

[@deathstalker7344]

Sir, how to find source impedance ? For matching impedance

[@M0NTVHomebrewing]

Hi there! If you mean how do you measure source impedance then I do talk about this in the video before (No. 49 - Impedance: The Basics). 73, Nick

[@deathstalker7344]

@@M0NTVHomebrewing thank you very much 😀