#45: Sweep Generator Basics and Receiver Alignment
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- เผยแพร่เมื่อ 18 พ.ค. 2012
- This video discusses the basics of a sweep generator, and how it can be used to observe the alignment of IF filters in a receiver. The video starts out by briefly discussing the frequency response characteristics of typical IF transformer cans, and how you and "manually" observe their response using a simple signal generator and a scope. Then, the fundamentals of a sweep generator / oscillator are discussed, and how these can be used to observe the "shape" of the frequency response of a resonant circuit like an IF transformer. The benefits of using a sweep gen, including the ability to observe whether multiple IF transformers in a single IF chain are aligned, or to see the "shape" of the skirts of a filter, is shown. While the video shows just a single IF can as an example, these same techniques can be used to align a receiver's IF by injecting the signal at the appropriate point in the IF, and monitoring its response.
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MAY GOD BLESS YOU. I'm 72 and starting to get back into electronics. I've ALWAYS had a hard time understanding how to use test equipment. But, YOU, have made it clear. Where were you 50 years ago when I was starting out? So THAT'S the difference between just an RF signal generator and a sweep generator and what they do. It seems so simple now.
I gotta check to see if you have any more videos posted.
+Mystery47 Well, 50 years ago, I was 3. Probably wouldn't have been much help to you! And yes, I have over 230 videos posted...
Same here have not done electronics tuning in over 40 years....really good video
I'll be 48 in a couple of days, got into electronics as a very young child, especially radio, been a ham radio operator for nearly 30 years, and I am just now REALLY getting into electronics. NO AGE is too old to learn! Good luck!
This video demonstrates why should teaching more practice in technical schools, like the way in this video.
Thank you for your comment. So 28 years old is not too late to start. Good luck!
I agree with previous comments, Alan is one of the best teachers on TH-cam. Alan, Paul Carlson(Mr. Carlson’s Lab) and Joe Smith have electronics/electrical engineering skills far beyond most humans. These three gents have taught me some very helpful lessons in their videos. Thank you for sharing your knowledge. I’ve learned more from videos on here than I ever did in a classroom for the most part. Learning how to build and tests circuits is the best experience anyone will get, guys like you and the others I mentioned show us how. 👍👍👍
Ben Eater too..
I appreciate your demonstrating basic concepts in ways that absolute beginners can grasp. Though I had an idea what a sweep generator WAS, it wasn't until I watched this video that I could see how I might USE it.... Like testing and tweaking filters for audio circuits, as I'm not (yet) into RF circuits.
Thank you Alan, your videos are great help in electronics for beginners like myself. I am currently an Intermediate Ham Licence holder in UK, and studying towards my Full licence exams. You have a great skill of delivering very easy to uderstand instructional videos.
Nixie based displays are absolutely awesome, and so are all your videos Alan thanks
Wow, Alan, you really nailed it! This is the first utterly clear visualization of the concept of alignment that I've ever seen.
Fantastic video Alan. I setup my signal generator to sweep a high pass filter that I assembled. The results are spectacular. Keep up the excellent work.
Well done Alan. As always, your videos are thorough and well thought out.
Thanks much for another great class! I needed this for working on a few older radios. Loved how well the scope shows you exactly whats going on.
Thank you for your clear and concise exposition of the subject. The preparation and quality of your presentation makes the concept easy to understand. You increased the value of my test equipment. Much appreciated!
Excellent. Head and shoulders above most other videos on this topic.
Most straightforward presentation of this topic I've seen. Love the Nixie Tube freq meter. Reminds me of the Heathkit one.
I built a Heathkit tube-based SW radio in 1968. Can't recall what I used to tune the IF. But to align, the book called for dialing up WWV (then NBS, not NIST)
Thanks for taking the time to produce this tutorial.
Another interesting, very clear video. A sweep generator is a huge help for filter checking or design, checking "Q"-etc. The uses for tuned circuits are limited only by imagination. Does not have to be real fancy either -from old boatanchors like Eico's and RCA's to newer used BK's, HP's and Waveteks, etc -if you can afford a nice DMM you can usually afford a sweep generator for your typical purpose. Markers are a nice feature. I think your videos are super for helping people see possibilities!
Cheers, I would never of though about that way of measuring without this video
The best of the best tutorials here! Thanks! I really enjoy watching your videos!
I am viewing more and more of your presentations. I just finished the oscilloscope post you gave to the antique radio group. That was a great one. I have a tek 475 and a rigol 1102. I just got a used B&K 4040a generator from EBAY and I am following your videos. Tnx a lot for sharing. .
Great video. A Contribution for the education in Electronics of future generations !
Thank you. The vid on DB explaining training actually helped me in my job the last week or two so thanks.
Nice! So, my is my check in the mail? LOL!
Needing to set up my FRG7 this is one of my favourite vids, thank you.
Very lucid and detailed explanation. Thanks.
Very good tutorial! Thanks for posting.
thank you w2aew for all this interesting and excellent material.
Your video's great on helping folks use their scopes! I have one that came over on the Ark... Going through your video's is telling me I might have a problem.
Excellent video. Thank you so much for this information.
I really enjoy your videos but I'm having a little trouble understanding how you are triggering on the sweep to get that image. Are you using the ramp or pulse on a second channel and setting it as an external trigger your scope. Could you please outline your connections to the scope. Thanks for this great video.
Thank you Alan. Priceless!
I love this video, you are a very good teacher. It would be great if you did a series of videos on how to use a spectrum analyzer for the absolute beginner to advanced use. The use of attenuators and when to use them, the dangers of connecting the analyzer in the wrong spot in the circuit. The do's and don'ts. Thank You
I'll consider that. I already have a few on the use/operation of a spectrum analyzer.
Real knowledge and skills, real video.
Thanks
Thank you for linking a "Visual Face" to topics that I wonder about! Greatly Appreciated!
Very clear and to the point love your work,
Very nice video that shows the virtues of having test equipment at your disposal.I have a feedback function generator with sweep facility and its invaluable coupled with the versatility of the oscilloscope to correctly align the freq response of a given receiver..excellent video sir.Take a bow.Regards Roger M0TDM.
Great video, you make things easy to understand, never thought of doing this, sweep jen, is now
on the to get list. thanks Dave W4GSM
Exactly what I needed. Thanks a lot! As always crystal clear explanation 😃. awesome 👍
Be forewarned not to physically couple the signal generator directly to the radio mixer grid, you will load the circuit and distort the curve getting poor results. Loosely couple using a loop of wire laying across the AM LOOP. DISABLE THE OSCILLATOR ! Monitor with a scope or meter at the secondary of the 2nd IF can. Use minimal signal level.
EXCELLENT Just what Im looking for! Restoring an RCA 1947 era radio receiver.
Awesome demonstration
WOW. I finally get it ! Thank you.
Excellent Video, agree with other commenter's. Always learn some thing new from your videos.
Worth watching repeatedly.
Thanks for video I had always shied away from sweep gens befor but have read about them in the past. A picture is worth a thousand words! Dan N9DH
I had a "sweep generator" once. I can't remember the make or model, but that was way back in 1974. It was specifically targeted for working on TVs, and not as generally useful as what you're showing here. Not only that, it wasn't even spec'd to deal with the then-current 40-some-odd MHz TV IF frequencies, but the earlier 25-some-odd-MHz frequencies. I don't recall when or how I parted ways with that beast, but I don't believe that I was all that upset about it at the time. :-)
I have bought an old thandar sweep generator and am in the process of repairing it. Your video was useful. The one I have has a different looking ramp it goes up and down at the same rate. I’m not sure i have the setup correct but have it going into channel 1 or X input on the Tek scope. This moves the dot symmetrical from left to right and the back right to left at the same rate. I have the actual output from the filter into channel two. Unfortunately there no manual available so just working through it. Great video. Regards Chris
Thanks for the excellent video!
Thanks for teach us. Great video! :D
Awesome explaination!!!❤👍👍
This is cool because at work I use a $30k HP 83650B sweep generator with the optional 83651 unit., but at home I have a HP 3324 which is both a function generator and a sweep generator.. synthesized though.. and somewhere buried in my to do list is a HP8601A sweep generator. Yay to power supply issues. I really have to get working on my old R71A which is slowly going deaf to both AM/MW and HF frequencies. Love your videos.
Awesome video! Thank you !
your vids are excellent
Thank you. I will look int both ASAP. Best Kevin
Excellent video :)
Great video.
Thanks... had been wondering if I really needed a sweep generator, when I didn't even know how to use one.
Great Video explanation.
Bloody hell look at your set up ducking hell! That’s epic
Great video! Thanks!
No problem. Instead of suggesting a topic, I just made a video here in my lab/shack that suggests a few things I might like to see you talk about/expound on, on your bench, with your equipment. It is on my channel and it is regarding the HP 652A test oscillator.
That nixie frequency counter is very nice!
its a thing of beauty!
Great video
Great video thanks
Incredible video! Always informative, I learn something new with every one!
Can you do a video on how to produce an eye diagram or eye pattern on a DSO?
You can manually (without sweep) get a curve shape by marking the output vs frequency on graph paper. This could be important for someone without the sweep equipment available who needs to occasionally check the pass curve of a filter or IF stage with a flat top. It is a bit time consuming, but it works.
Excellent.
Excellent. Thanks.
Very nice - thank you.
Wonderful. Got it. 🎉
Thank you.
Thanks a lot man :)
Great tutorial and explanation. WIthout the luxury of a mentor in my quest for better and greater repair capability this tutorial was REALLY helpful! Thank you. j
A couple questions: what are the probabilities of IF cans such as these going out of "tune" in either newer or older tuners? And is the tuning of IF cans a normal part of receiver alignment? That is normally found in re-alignment procedures?
Keep up the great tutorials! I'd love to be able to call you at times! :-)
Edz
Thanks..I need to replicate this to learn more about my scope. ...other than how much dust it can collect.
For broadband signals it is often necessary to tune the center frequencies to different equally spaced values to avoid rejecting information far from the carrier frequency. Television and high bit-rate digital are two examples.
Very helpfull
awsume learned a lot from your channel .
Ohh- what would be cool is a video on using a sweep frequency generator and a scope to do component curve tracing/matching. Also for those with minimal equipment -using a signal generator and a scope to use lissajous patterns to do frequency determination/comparison and cool stuff like that.
Hi, very instructive video indeed. Thank you very much. I'm trying to learn how to properly align AM and FM radios myself and i'd like to know how to properly hook up an oscilloscope @ the end of an IF chain without influencing the tuned frequency of that chain by having too strong of a coupling/loading. So, it would be nice to know what kind of probes are suitable for the above and also when tuning the FM portion what kind of generating equipment is needed considering that in FM we are dealing with stereo signals and we want to keep the distortions low when tuning the discriminator coil for instance. And how one can measure the level of distorsions while doing it if there is only an oscilloscope at hand? Thank you.
very useful video, please let me know that there was any capacitor connected as shown in the schematic at primary side?
I have a national nc300 on the workbench right now that I finished re-capping last night. I want to do an IF alignment next. Using this procedure do I do the second IF first, and then the first IF Can? I'm curious as to your thoughts...
So cool! Thank you Alan. Do you have to physically remove the IF transformer from the radio to do this alignment though? That would seem to be excessive if it were the case.
Cool !
So if I am aligning a radio, let's say an AA5 for example, where would I connect the sweep gen and the scope? Would I connect the generator to the plate of the converter tube (with a DC blocking cap) and the scope to the grid of detector tube with the radio on? Or would i just tune each individual IF can with the radio off?
Many thanks for this very clear video. Couple of questions: If we have two IF transformers I understand you recommend probing the output of the second transformer and hopefully checking there the effect of both transformers. I guess it would be the same if we probe the output of the first nd adjust and then the second. And second questions: it seems that in this setup a marker generator (which is required by the service manual of the radios I am trying to adjust) is not needed as we know the min and max sweep frequencies and hence all the intermediate ones (if it is a linear sweep).
Ideally you would want to probe "one stage away" from the one you are tuning to avoid potential for the probe affecting the resonant frequency.
I am seeing this 9 years later. Thank you. It would be great if we can see this technique used in an actual receiver to show, where to inject signal, where to read and what we have to worry when the "cans" are in circuit. A future video? Thank you! VA3GPJ
Hi Alan
I recently purchased a used BK Precision 4040 sweep function generator and was able to reproduce most of what you did in this video. Is there a simple way or circuit to introduce a marker at a given frequency.
Thx again
This is a great video and explained very well. Question, how would I do this when the IF can is in circuit?
Hi, Alan what would be other use of a high frequency sweep oscillator in the 10-20Ghz besides of checking test equipment?
This is even better than spending an evening reading the ARRL handbook. Thanks again w2aew! de ki4dbk
So im looking for a good way to align a Fm tuner. You think this is a good way of doing it?
I have been trying to work out how to view the slope response of an IF strip on my scope with a sweep generator. Your explanation and use of the pulse/ gate output has explained how I can use this as a start stop reference. Could you just confirm you are triggering off the pulse output on the signal generator? Thanks.
I have acquired several new sector antennas that unfortunately have no identifying marks as to manufacturer, model, frequency, etc. Based on other information I have I am fairly certain that they are either for 900MHz, 2.4GHz, 3.5GHz, 4.9GHz or 5.8GHz use. I am not sure how I can tell for sure which band though. I have an HP 8565A spectrum analyzer as well as a variety of scopes. Do you know of a way that these tools might possibly be used to help identify these antennas? Thanks!
Got me a Hammarlund HQ-129-x that needs an alignment. I did it by ear so far, but now I can do a more quantitative alignment.
The question I have is: How can I increase the gain in the RF so I can hear the stations it picks up?
What brand and model sweep generator are you using here? Thanks for all your videos and time spent making them!
I used a Leader LG 1311 Function/Sweep generator.
Thanks for another great video Alan. Question: you seem to be showing us the ramp and gate waveforms _before_ setting the sig generator for sweep mode. Certainly before you set the start and stop points. I must be missing something.
Also, how different would these waveforms, or process, be using FM? maybe an idea for another video?
Nice, u should be a teacher.Would like to suggest u do two using the scope n sweep signal generator. Aligning an old tube( cause they're very touchy)FM broadcast radio with a ratio detector and the second on a more HiFi type limiter/discriminator set.I had a lot of trouble with older tube based stereo stuff like H.H.Scott 340 early receiver not tripping into stereo.Turned out my alignment with just a v.t.v.m. had resulted in not enough pilot signal for the multiplex to work with. Only two very strong local stations would actuate the stereo function.After looking at the I.F. response with the sweep gen n scope discriminator was way off. I was picking audio up off the positive peak instead of the straight side of the slope as it should.I think it would be a very helpful set of bids. Thanks....N2VUW
Also, I've heard you can determine the resonant frequency of a circuit using an LCR meter. Is that correct? How would you set that up?
thanks for getting back. what would be the width of the sweep? at 10.7Mhz, what would be the recommended start/stop freq?
I have a Elenco Kit of a transistor radio that needs to be tuned. I have a oscilloscope and a audio generator. Does it matter what type or RF generator that I should buy next?
I don't know if I can use the same method and test points(front end and discriminator) that was used in shango066's FM alignment video. Based on my understanding from his reply, that method requires a BK415. He's making a vid response on how to align using signal gen and VM. Thanks for your guidance.
At time index 5:37 you mention the sig generators Trig/Sync output is a really "handy one to have" - can you mention how we might take advantage of that? I'm learning to use my HP3336c and it has a Sync/TTL output. Great teaching, thank you.
OK, thanks Alan. I thought that was the answer but wasn't sure. Can the scope camera connections on the old mainframes (like 7904, etc) easily be adapted to use/sync modern digital cameras with for that purpose? Know anyone who does that?
Is there a capacitor across one side of that inductor can for a LC circuit? Or are you just seeing the inductor's response by its self?
very similar to the procedure you would use to tune like a duplexer for a repeater ??
that would make a great video too,,
1:53
Great video as usual.
Is there a video for aligning the transmiting and receiving frequencies between the base and the handset of a cordless phone ?