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This video describes how a classic double-balanced diode-ring mixer operates. Very basic mixer theory is quickly reviewed, which describes how the sum and difference of the LO (local oscillator) and RF (Radio Frequency) inputs are generated at the IF (intermediate frequency) output. It is also noted that the sum and differences of the harmonics of the LO and RF are also present at the IF output. Math waveforms on the oscilloscope are used to illustrate the operation of the mixer, and the actual waveforms from the mixer are compared to the math waveforms and the differences are discussed. A detailed description of the operation of the mixer is presented, including the switching action of the diodes. Finally, the frequency components are are expected from the mixer are shown on the spectrum analyzer. For more information about how diodes are used as switches, please see the video at this link:
• #82: How to use a Diod...
Also, for another tutorial on mixers and their use in frequency conversion and translation, check out this video:
• #83: Basics of RF Mixe...
And, here's a video that shows how I wound the trifilar transformers used in this circuit:
• #166: How to wind a tr...
And, here's a video that shows how I wound the trifilar transformers used in this circuit:
• #166: How to wind a tr...
A copy of the notes in this video can be found here:
www.qsl.net/w/w2aew//youtube/D...

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29 июн 2024

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Комментарии : 328

@arthursgarage6550 Месяц назад

Man, can I just say you are one hell of a good explainer of RF stuff

@SamGallagher 8 лет назад

W2AEW, aka Alan, you're the KING of RF electronics videos. You hit the stuff I never totally understood, and in the best way. Rock on man

@pdxfunk 6 месяцев назад

Fantastic video, thank you! Literally almost all the information on the internet is calling a 4 quadrant multiplier a ring modulator (It's not!!). This is the only video I've seen that gets it right.

@AppliedScience 10 лет назад

Very helpful and well explained, Alan. Thanks!

@whawaii Год назад

Thank you for this awesome presentation. As I was following the "Scope Overview" section where you list the 2 frequencies (7 MHz & 10 MHz) being combined, in my head I'm already calculating the resultant frequencies as 3 MHz & 17 MHz. You really threw me for loop at 2:08. I did a "What?!?" double-take & went back to hear that again when you stated that the upper frequency would be "13MHz". I started doubting my own RF & LO knowledge. Thankfully, the rest of the time you referred to the upper one as 17MHz. [You may wish to consider posting a notice of this misstatement.] Thank you.

@Afrotechmods 10 лет назад

Another amazing video. Thank you Alan. If you are open to requests, I would love to see videos about mixers that use as few magnetics as possible with the goal of reducing PCB size and cost.

@absurdengineering 2 года назад

A trifilar transformer like this for say 2-5GHz is the size of a 1210 capacitor if you wind it yourself. It’s even smaller - a small grain of rice - if you buy it and it costs pennies. Kinda hard to beat with discrete parts. The only way to beat it is with transistors on a chip: those are usually “free” compared to anything discrete. So if you really want low cost, use a dedicated mixer IC, or make an ASIC for your application that will replace other discretes with free transistors :) When pricing discrete parts, the cost is in raw materials and processing of each unit: a discrete run-of-the-mill transistor costs about as much as a discrete inductor or transistor of a similar size and volume. When costs matter that much, you’re talking hundreds of thousands or millions of units. At such scales, small magnetics cost about as much as small anything else, to a first order. Even the costs of inserting the component start to matter at such scales. For anything made at hobbyist scale, the cost of labor wipes everything else. PCB and other stuff is essentially free, and it costs more to ponder about it than to just put it on the board and move on if it does the job to spec you need :k)

@hofjen66 5 лет назад

Your tutorials are the best I've ever seen on RU-vid! 73 de DL1WW!

@Whiskers1949 7 лет назад

I actually followed this all the way through.....a testament to your presentation. Thanks!

@DantalionNl 8 лет назад

I love how detailed and in depth your rf videos are, your'e the only one who makes decent videos about this its awesome! keep it up.

@volvoC70II 9 лет назад

You did a great work, making sketches and explaining how the mixer works. In these 10min I have learned more, then from reading books for 3 hours. Thanks!

@stefanopassiglia 7 лет назад

Super. I got back to working on electronics after looking at one of your "back to basics" video, and I am still an audio frequency guy but I love learning about RF which is a domain I touched really very lightly during my studies. Thanks for these fantastic videos.

@phoenixcrp 8 лет назад

The regular electronics hobbyist could not justify the expense of owning such a nice mdo piece of gear (around $14K tag price) I would like to thank you, Alan, for your generosity on producing videos like this one. The 50K frames in this video are priceless for many of your followers.

@w2aew 8 лет назад

+Frank Acosta I do realize that I often use equipment that is outside the reach of the hobbyist. I am very lucky to be working for Tektronix and have access to this fantastic equipment. I hope that the use of this equipment serves to help viewers understand the topics and concepts being presented.

@StreuB1 8 лет назад

+w2aew It does....I am a design engineer with a big mechanical background and a "working" background on the electrical side of things. These videos have really expanded my scope of understanding. Especially in the industry I work in. It opens my eyes to a lot of the things my companies technology does.....metal detection.

@God-yb2cg 6 лет назад

I was actually thinking: "that scope would be a waste in my possession because I wouldn't know how to use half it's features"

@ernestb.2377 11 месяцев назад

Thanks for the explanations! There are so much specific details in RF electronics..

@retro.jonnes 3 года назад

This is the best explanation about mixers I found over the YT! Thanks!!!

@striker851 8 лет назад

Thank you for such a well thought through explanation. I'm still trying to wrap my head around AC waveforms and the math, but you really helped to visualize it.

@m8uwut 10 лет назад

Lots of info, learned something new today. I'm sure it will be helpful in the future. You're doing Gods work.

@ozzyfromspace 6 лет назад

This is amazing! Who on Earth could have possibly disliked this video?

@kolinevans9127 4 года назад

The ‘never Tesla’ crowd ?

@devjock 10 лет назад

I'm subscribed to the synth-diy mailinglist and there's so much material that's common between these two areas. Besides the diode nonlinearity, which in audio-synth territory gets kinda fixed by an ideal diode circuit (fancy balanced opamps), it's basically a ring modulator! Crystal clear explanation as always, much appreciated for uploading!

@habiks 8 лет назад

Did they name a school after you yet?

@w2aew 8 лет назад

No, not yet.

@commandercortez 7 лет назад

I feel like it's worth mentioning that the non-linearity of the diodes is what makes the "cos(a+b) + cos(a-b)" (addition and subtraction of the input frequencies) components appear in the output signal. Otherwise, what we've created is just the sum of two signals sin(a) and sin(b), which can be achieved without the use of diodes or switching at all.

@outsideaglass 4 года назад

These videos are super helpful with the COVID19 quarantine preventing us from going into the lab (and with professors who aren't capable of making videos) - thanks a lot! You're a life saver!

@berni8k 10 лет назад

Thanks for the nice and simple explanation, i don't do RF stuff but i always wondered what these mixers are that i see everywhere.

@UberAlphaSirus 10 лет назад

Thanks to you w2aew, RF is becoming less voodoo magic to me. Thanks :D

@ronjones4069 7 лет назад

By far the best, clearest explanation of how the DBM works. I kinda' understood them, but now I feel as I DO understand them. THANK YOU!! You are the man!!!Ron K7RJ

@w2aew 7 лет назад

Thank you for the nice comments! I hope you find some of my other videos just as helpful. Be sure to check out the video index .pdf file that is linked on the main channel page (lower right corner of the banner graphic).

@outsideaglass 4 года назад

Your videos have definitely saved me this term. With COVID19 shutting down the labs and everything's moved online, it's been really hard for me to learn just from my professor's lectures and no lab work. I was really struggling til I found your videos. Thanks so much!

@w2aew 4 года назад

Very happy to hear that!

@thisnicklldo 9 лет назад

Terrific video. It must take you a long time to get all these diagrams and oscilloscope setups working, but they really make things clear. Thanks.

@w2aew 9 лет назад

Sometimes the preparation work for producing a video like this can be several hours, or even a few days of spare-time tinkering.

@allanseward7293 6 лет назад

It was great to visualize the results from multiplying the cosine waves at different frequencies. Thx

@TheBrandel111 5 лет назад

Finally, I understood this circuit! Thanks W2AEW!

@bain5872 10 лет назад

Exceptional! Truly enjoyed it.

@yytvo212 Год назад

The explanation on the diode circuit diagram is amazing and in-depth. Classroom courses pale in comparison.

@emylrmm 4 года назад

this explanation is very nicely done

@kedmark 4 года назад

Exactly what I was looking for, tyvm for posting.

@fjs1111 4 месяца назад

wow Alan, that was awesome. I knew how mixing worked, but to see the ways you did this it really made me think.. Also -- that was really cool to see a custom math expression on a scope, I've never seen custom expressions before, only built-in

@stephenmoore2754 10 лет назад

Thanks very much for an informative video. Sometimes it takes one key piece of information to turn the light on in the ole noggin and you did it. I have been wondering for years just WHERE the information in an AM signal (sidebands) was located with respect to the overall signal. Watching it on a spectrum analyzer is one thing, but to see in on a scope trace is another. You answered a question that has been bothering me for years. I know that you can see the relation in the math, and that "stuff" may be found in other quadrants of the graphs, but your explanation finally showed me HOW it is related in the time domain. Great stuff. Now if I can translate this to a better understanding of SSB. . . . .

@MoTown44240 6 лет назад

Jim, AC8NT my Extra Class instructor showed this and three more of your videos tonight. I am one of those is having/ has been having a difficult time understanding electronic theory. I am struggling. Now that the former Advanced and former Extra class material is combined I will be attempting to pass Extra in 5 weeks. This is my 2nd time in Jim's class, last time was 18 months ago, and I am still having difficulty grasping the ET concept. Thankful for guys like you and Jim though. Terry KB8AMZ

@TechTins_Projects 10 лет назад

Thanks for this. Love it. I never really understood diode mixers. Now I do!

@gardoomforge8273 6 лет назад

An amazing explanation! Than you very much and keep up the good work!

@gregorymccoy6797 2 года назад

Thanks so much. I came here from your other mixer video. I've got a good handle on this now, at least for this type of mixer. I'm more of a digital domain, embedded guy but am getting the urge to try some RF projects.

@rustukaya9342 9 лет назад

Thank you sir, couldnt be explained better.

@dietmarzabel8220 6 лет назад

Very well explained! Many Thanks !!!

@budleyca1 10 лет назад

Great explanation, thanks Alan... Bud...

@thomasoffenbecher2196 4 года назад

Excellent explanation, thank you very much.

@dirkpeters9611 3 года назад

very good explained. Thank you !!!

@1bizjets 4 года назад

Good refresher. Thank you.

@uygarglk Год назад

Thank you for great explanation.

@virtualan 3 года назад

Great stuff Alan.

@user-hl3en7wu5u 4 года назад

Thank you very much for detal video about diode ring mixer!

@raphaelcardoso1194 4 года назад

Learned a lot! Thanks!!

@tamyk64 8 лет назад

Learn a lot from your video, thanks !

@MrCarlsonsLab 10 лет назад

Hi Alan! I have recently found your videos through making my own. I Just started making videos, and guys like you are a great inspiration to keep going. We have a lot in common I see. I have a scope collecting problem "ha ha" ....... Well, test gear collecting in general.... And so on. Great Videos! And keep it up. My subscription list is still small, but your now in it!

@w2aew 10 лет назад

Thanks! I've subscribed to your channel too.

@markbell9742 10 лет назад

The ‘Math Expression’ in Tek MDO3104 is very neat; a scope married to an Excel spreadsheet (or to the more highfalutin: MATLAB or Mathematica). Cheers, Mark

@garygrove2884 2 года назад

Very interesting video Alan !! I noticed that my IFR-1000S has similar circuits that seem to mimic your Diode Ring Mixer video !! 73's Gary Grove

@electronicbob6237 8 лет назад

Wow..great explained...!!!

@rampravesh4065 7 лет назад

excellent, Alan. Thanks

@RandomlySelectedUserName Год назад

Thank you for nice explanation

@mrjohhhnnnyyy5797 10 лет назад

2:15 Dave's ruler, that's nice!

@JimGriffOne 10 лет назад

I tried building one of these to make a 38kHz DSB-SC subcarrier for my FM radio transmitter. It worked, but my whole project failed when it came to trying to make a nice 19kHz pilot tone (sinewave) while also having a perfectly in-phase 38kHz sinewave to modulate the L-R audio. It gets so complicated! Wish I'd chosen electronics when I was college age.

@AntiProtonBoy 10 лет назад

One of the things that is a real grey area for me is winding coils and transformers for a circuit like this. Is there are good introductory material on choosing the right ferrite material, geometry and so forth? Perhaps you could discuss this topic in a new video, if appropriate?

@TrystansWorkbench 5 лет назад

Here is one of Alan's videos on winding the coils for this: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-a8ViWS61hsU.html

@thanghoang8803 4 года назад

Excellent!

@rsim22 5 лет назад

Fantastic video! - Any chance you can do a similar video on the JFET ring mixer?

@giorgioferreroTO 6 лет назад

this channel is Amazing

@w2aew 6 лет назад

Thank you. Be sure to check out the index of all of my videos: www.qsl.net/w2aew//youtube/W2AEW_video_index.pdf

@giorgioferreroTO 6 лет назад

w2aew thank you

@MultiSchuman 2 года назад

awesome and subscribed

@joaopaulocoelho5401 2 года назад

Another perfect video. It would be nice to talk a little about the transformer. How the number of turns was found? Any math involved or just trial and error? Thank you!

@kautsarfadlyfirdaus1879 7 лет назад

very helpful

@ebear1ca 10 лет назад

I have re designed the front end board in my old Yaesu FT-101 by Replacing the RF amplifier FET with a 3N211 or a 40673 which I have and using a MC1495 as a 1st recieve mixer as well as the 2nd recieve mixer to get rid of some of the birdies found in the rigs pass band. After what you tell me about dynamic range and higher intercept points I am now concidering using either a shottkey diode DBM or DDBM if I have enough LO drive. Ted VE6AMR

@johnrinehart 9 лет назад

That was a really good explanation. Thank you very much for this. The only (small) modification I would have made to this video would be to change the math to have your logic driven by the transition level of the diodes (assume .6v for the 1N5711) only after you show the IF signal at the mixer output. This would help demonstrate that the zero portions are due to diode transitions. I saw that you used the LO to demonstrate this. But, it would have been good to see that mathematical waveform approach the measured wave. Also, it seems that the measured signal lags behind the math waveform (see 8:52). But, it's hard to tell without taking the difference of the mathematical waveform and the measured signal. Can you confirm that this is happening and can you explain why this might be happening? Thanks, again. Really, it was a great video. I could not have done better myself.

@w2aew 9 лет назад

John Rinehart Thanks for the nice comments. I haven't taken that close a look at those small phase shifts, although it looks to me that the measured waveform is slightly leading the math waveform. I suspect that it is at least partially due to the difference in phase shift through the transformers (and I was measuring the signals on the primaries.

@markussteinbacher8807 6 лет назад

very informative video. Thank you Alan. Did the amperage in this system rising when reducing the frequency ? aka mix 100khz with 1 vpp and 50 khz 1 vpp equals 150 khz and 50 khz with twice ampere ?

@seyedmarashi 5 лет назад

it is best video to well know RF

@Arijit_VU3ICT Год назад

Great.. sir please make a video on working of bfo. Also a video on total working of bitx20 by OM ashar farhan with tx and rx procedure. Thank you.

@Koolandonymous 6 лет назад

very helpful video ....alan. can u please simulate the same using any software.

@ericacopenhaver 9 лет назад

Thanks for this tutorial! Why, however, does the LO alone set the direction of the current in your analysis? Why doesn't the RF signal affect the current? Do we need to assume that the LO's amplitude is much greater than the RF?

@w2aew 9 лет назад

Yes, that is typically the case. When you look up commercial mixer specs, you see Level-7 mixers, Level-10, Level-13, etc. This refers to the power of the LO signal (7dBm, 10dBm, etc.).

@tim46767 9 лет назад

Thank you for this great tutorial. But I have another question: How works a Polyakov mixer?

@marcisberzins 4 года назад

Polyakov mixer in his DC receivers works with large signal from LO (with frequency two times lower than the signal frequency), which turns on the diodes twice each cycle (one diode for +, other diode for -) and the RF signal, which is small, is sent to the output at these times. We have at the output the difference frequency between 2 times LO frequency and RF frequency.

@tulsEE87 Год назад

Thanks for clearing concepts. Can you please say is any low frequency (kHz) QPSK modulator available or not?

@arimateiaalves3349 6 лет назад

Congratulations great video, wanted to know if when you were measuring the signals used some component that is not described in the list I could not reach the measured results

@w2aew 6 лет назад

The parts I used are listed on the first page of the notes. www.qsl.net/w/w2aew//youtube/Diode_ring_mixer_operation.pdf

@arimateiaalves3349 6 лет назад

thanks

@Falican1 4 года назад

Hey! do you have a video where you explain about the harmonic terminations to avoid reflections? thanks!

@w2aew 4 года назад

I'm sorry, I don't...

@SopanKotbagi 4 года назад

What kind of diodes can we use for making these double-balanced diode-ring mixers? And what determines the frequency window of operation of these mixers, if any? Great video as always. Thanks!

@w2aew 4 года назад

High speed schottky diodes are the most common. The design of the transformers (number of turns, core material, etc.) will largely determine the operating frequency range.

@adilmalik7066 7 лет назад

is the leakage you pointed out in the spectrum the same reason we see "LO feedthrough" on spectrum analysers? excellent video!

@w2aew 7 лет назад

Similar, yes.

@cozycactus 7 лет назад

hello..can you do video about antiparallel diodes mixer? that works on half frequency of local oscillator

@peterfitzpatrick7032 4 года назад

That 'scope is thirteen & a half grand (€) here in Ireland 😔☹ But at least I am blessed to have your teaching & demonstrations for free here on the Tube... for that I sincerely thank you !! 😎👍☘🍺

@w2aew 4 года назад

I am very lucky to work for Tektronix - so that helps!

@abdula4256 5 лет назад

Thank you best 73s

@omsingharjit Год назад

please explain and make little circuit of how Tuning Meter Led indicator circuit works in old Radio ?

@awesomeblossom6557 3 года назад

Great informational video! Your videos help a great deal when I'm trying to work out something of my own. Quick question: @ 6:42 when you are explaining the negative state of the diode mixer ring, I'm assuming the input is still LO, but in the video and in your copy of the notes, it's written as IF.

@w2aew 3 года назад

Yes, this is a mistake in my notes. Thank you for paying attention!

@w2aew 3 года назад

I've edited the PDF to correct it and uploaded it.

@awesomeblossom6557 3 года назад

Ah wow! Thank you sir, appreciate it.

@jeffscaparra6985 8 лет назад

So would using a square wave for the LO clean up the signal because the diode mixer would transition on and off faster? would some weird combination of a square and sine be better? Is this accounted for in actual circuits or is a different type of mixer preferred?

@caulktel 7 лет назад

Jeff Scaparra There is a lot of discussion over on the Bitx20 .io groups about this. Personally, I would rather use a sine wave rather than a square wave full of harmonics. Joel KB6QVI

@jeffscaparra6985 7 лет назад

Cool I will check that out

@RechargeableLithium 6 лет назад

Joel - we want to use a square wave because we want the sharp turn-on and turn-off of the diodes. Matching the four diodes, feeding enough power in from the LO, and having a 1:1 SWR at all three ports will keep the signal clean. For more, Pete Juliano has a three-part RU-vid series on the topic, and details can be found in "Solid State Design for the Radio Amateur" as well as the 'QRP Homebuilder" archive. nt7s.com/files/QRPHomebuilder.pdf ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-kzcvNzpMv3U.html 73

@johnc8910 5 лет назад

Disagree. You do NOT want extraneous harmonics generated in your mixer. Extraneous harmonics give extraneous images which can complicate selecting just the desired sum or difference frequency. Diode matching is not a problem with modern components. You can buy a quad ring part with 4 matched diodes for less than 4 individual diodes. Optimum LO injection is 7 dBm.

@andrewferg8737 2 года назад

Question: I've built a diode mixer for AM modulation and compared it with the Gilbert Cell modulator. Does the diode version always suppress the carrier? or can it be adjusted produce a traditional AM signal like the Gilbert Cell?

@w2aew 2 года назад

You can sort-of do this by adding a DC offset to the baseband signal applied to the IF input.

@maro8D 7 лет назад

Hello Alan, great video as usual! But I have some questions to it: 1. You have your LO amplitude set to 400 mV is it enough to switch on 2 diodes? When I see a diode I automatically think of 0.7 V voltage drop. I think it's hard wired in my brain after school :) 2. I understand that the RF signal amplitude must be below voltage that turns the diodes on is that right? So that only LO controls the diodes. Did I get it right? 3. Is the LO amplitude picked so low intentionally so that there is not clamping from top and bottom?

@w2aew 7 лет назад

Hello Marek. I'm using 1N5711 low power schottky diodes in the ring. The Vf for these schottky diodes is about 1/2 of that a regular junction diode. The LO is used to modulate the diodes. The RF level is generally kept well below this to minimize distortion. Best (lowest) conversion loss occurs when the diodes are fully switched on/off, but the mixing happens even if this isn't the case. As long as the LO and RF are combined in a non-linear manner, the mixing happens - it's just that the conversion loss will be higher. When the LO power is high enough to fully switch the diodes, there is a fair amount of harmonic distortion visible on the LO drive waveform. For this video, I didn't want to get into that level of detail, so I kept the LO drive lower to keep the video length reasonable. Thanks for the good questions.

@stevejin9459 4 года назад

Marek The mixed two signals on diode should be less than 0.6v( for silicon diode) to have less current. That makes the load to both transformer light, hence less signal distortion to signal source. Also, less power consumption by the circuit. Diode has non liner v-I curve, in all range from 0.x volt to couple volt. That how the diode makes the added voltage of the two sources to multiplied current, measured by the resistor in serial . The diode ring also called ‘Gilbert cell’ question from stackoverflow, electronics.stackexchange.com/questions/307776/why-do-diode-rings-multiply

@StreuB1 8 лет назад

I have been thinking about buying an entry level scope for hobby HAM work and basic learning, similar to what you are showing here. I am looking towards the Rigol brand but for giggles I thought "How much does the scope Alan has here, cost?" So I googled it.....and that led to about 90 seconds of nonstop laughter. :-D You are a professional that does this for a living, and it shows through the cost of your test equipment. My hat is off to you my good man, you have IMPRESSIVE kit. :-) - N0BPS PS now watching some of your other videos to understand bandwidth to see if the Rigol 1054z is a worthwhile scope for HAM radio use and general learning......there is also the 100Mhz hack for it...not sure if that is important or not.

@lingen2193 8 лет назад

+Brian Streufert the Rigol DS1054Z is generally a no brainer as a beginners scope. You'll never regret buying it. However, it is in no way comparabale to Teks "middle" class scopes, they are simply fantastic instruments. And the MDO3000 series starts at just 3,5k$ ;-).

@ronjones4069 7 лет назад

I could not agree more... the Rigol is the best per buck out there. And, they don't cost much more than a used TEK with fewer features.

@JosiahRitchie 7 лет назад

I looked around and considered used scopes among other things. I ended up with a Siglent SDS1102CML. I'm still learning to use it, but it seems to fit the bill so far.

@ronjones4069 7 лет назад

I might add, digital scopes are wonder, and you should have one in your future, however if you can pick up a 20 MHz old analog scope for less than $50, you should consider it. They are dirt simple to use and will give you some experience using a scope before you plug onto the more confusing (but much more powerful) world of digital scopes. I have a cheapo 20 MHz scope that I love for its simplicity. I won't be without my 200 MHz giga sample huge memory USB run data box, but generally the ole trusty analog job does just fine. Before you guys with your fancy dancy data acquisition wonders flame me, remember this guy is where we all were and just need practice going at waveforms in real time. Remember when we did that just for fun, and how much we learned about electronics before the computers got in the way.

@malgailany 10 лет назад

Nice!

@copernicus633 3 года назад

Question about theory: The diode ring mixer shown here seems very different from the Gilbert Cell mixer described elsewhere. The diode ring seems to “chop” one frequency with another frequency. That doesn’t seem like “multiplication”, but more of a harmonic creation mechanism. The undesired harmonics are eliminated with filtering, but with losses from the energy spent in suppressed harmonics. The Gilbert Cell seems like a true multiplication, where the product of 2 sinusoids is produced accurately, without creating a lot of extraneous harmonics. It is therefore less noisy. Is this a roughly true comparison?

@w2aew 3 года назад

Basically yes. The diode ring can be though of as a multiplication of one signal by an alternating +1 and 0, or +1 and -1, as opposed to a continuous multiplication. Even the Gilbert Cell can (and is often) be driven into limiting, thus giving a similar result to the way the diode ring mixer works.

@zerovolt24 Год назад

Hi Alan, would 32 AWG also be ok? T37 is really small. Maybe 30 AWG is good for bigger toroid diameters too, so I can only buy one coil to suit all.

@w2aew Год назад

Sure, that would work

@danielperez761 9 лет назад

Excellent explanation of the operation of a mixer. Regarding to it, I have a question to you. I need to compare two input standard signals of 10MHz. I could use a good interval counter to do it, but I need to have a better resolution. Then we decided to use a frequency mixer in order to obtain a frequency difference of some Hz ( 300-500Hz) at the output. My question is how to calculate the construction of the two baluns (how many turns and the diameter of the wires) so they can work on that frequency with the same circuit that you show in the video.

@w2aew 9 лет назад

daniel perez General practice is to make the inductive reactance of the winding to be 4 or 5 (or more) times the impedance of the circuits driving it. For 50 ohm applications (typical), the windings should results in a reactance of 200-250 ohms or so. The number of turns can be determine by using one of many online calculators like the one shown here: toroids.info/

@danielperez761 9 лет назад

***** many thanks for your quick response! It is very useful to us and we will build our mixer immediately in accordance with the data that you have provided us.:)

@josepaul2000 9 лет назад

Thanks for the video! I am wondering, at 4:42 , could the 'LO' may well be a square wave? (since the mathematical expression simply detects the zero crossing) If so, the output doesn't seem to look so bad, why do we care so much about getting a low distortion sinusoidal oscillator? Or is that more relevant in circuits with 'better' mixers?

@w2aew 9 лет назад

It does depend on the mixer design, but in this case, a squarewave LO would work

@guenaziz2 3 года назад

Thank you so much for this video. I tried to find good explanation of how could diodes make the mixing, but never found any relevant one. Thank you Alan!

@ToddFun 10 лет назад

***** At 5:15 the circuit on the right doesn't have an LO input but does have an IF input and an IF output. This is a mistake? or is there something I don't quite understand?

@w2aew 10 лет назад

Good catch! Of course, the port on the left of the right-hand circuit should also say LO.

@DumbledoreMcCracken 6 лет назад

Awesome

@CH_Pechiar 10 лет назад

Alan, can you show us more in detail the mixer, ie, the hardware you buit? Which diods, etc. Thanks, CH

@w2aew 10 лет назад

The details are on the schematic. Diodes are 1N5711 Schottky diodes. Transformers are trifiler wound on T37-6 cores. The previous video posted on my channel shows in detail how I made the transformers.

@CH_Pechiar 10 лет назад

***** thank you.

@kd5ozy 9 лет назад

I just built a HV leakage tester from a microwave oven trxfmr, and I do not find any charts on maximum allowable leakage in ua for non electrolytic caps. Can you do a video on the theory behind that and maybe explain some type of formula relative to that. I really enjoy your videos. I am lost! James

@w2aew 9 лет назад

I would think that the maximum allowable leakage rate on a non-electrolytic capacitor would be purely governed by the application the capacitor is being used in. Different dielectric types have different leakage characteristics, so there's no one formula to predict the leakage current.

@robertfranks5376 3 года назад

Hi Alan. I had a question about your directional coupler video. You used the outside conductor of a piece of coax as a Faraday shield by grounding one side. Why doesn't this allow signal current to flow in the shield, and wouldn't this cancel out the EM energy from the inner conductor so that the toroid current- sensing xfmr would sense zero current since the toroid surrounds both conductors. Thanks.

@w2aew 3 года назад

The faraday shield does not block the magnetic field (only the electric field), so there is still magnetic coupling to the toroid transformer.

@robertfranks5376 3 года назад

@@w2aew Hi Alan. Thank you so much for your response. I was thinking that the magnetic field from the electric current returning through the shield in the opposite direction to the current in the inner conductor would cancel out the magnetic field from the current flowing through the center conductor. Thanks again.

@raybarron316 7 лет назад

Alan, I'm considering building the SDR dongle upconverter from the QST article written by James Forkin (WA3TFA). The double balanced mixer he recommends (SRA-1) is going to cost almost as much for shipping as the mixer itself. Could your diode ring mixer be used as a replacement for his double balanced mixer? The part schematic and yours look almost identical.

@alanwolke6253 7 лет назад

One of the benefits of the purchased mixer is that the diodes are likely well matched which gives good RF and LO rejection. For this application though, this isn't that important. The homebrew mixer should work well.

@BrendaEM 2 года назад

I find mixers interesting. I realize that this is an entry-level, rudimentary mixer, but... Could this general type of mixer be biased into either the positive or negative, (and then capacitively/AC coupled) to reduce the crossover distortion causing the odd harmonics? This is a good video, as most of yours are. Thank you. (Generally, I have been so impressed by Amateur radio licensees/operators knowledge of RF electronics that it prompted me to get my General.)

@w2aew 2 года назад

Adding DC bias can negatively effect the balance of the mixer, and thus negatively impact the LO and IF/RF rejection. Sometimes a *small* amount of DC is added as an adjustment to improve the balance.

@BrendaEM 2 года назад

@@w2aew , thanks for the reply.

@gregpeterson7946 3 года назад

One aspect I have not seen addressed (yet) is drive level. The signal amplitude at the diodes I think should be at least 1.5 v, since 2 x silicon diode voltage drops of 0.7 v would be at least 1.4 volts to turn them on. But I do not know what the transformer ratio is, so I cannot guess at the LO amplitude. I also would like to play with IF filters, but do not know the proper drive level. My initial thought would be to drive a filter (mechanical, crystal, or piezo) with a sig gen at the filter's center frequency, slowly increasing the amplitude until I see some saturation evidenced by output ceasing to increase. At some point, I would expect damage from excessive drive, so I would like to stay below that. Radiofun232 comes close to addressing this with some of his lash-ups, but my questions remain unanswered.

@w2aew 3 года назад

I do address this topic in this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-GvadQpkZ8l0.html