To learn electronics in a very different and effective way, and gain access to Mr Carlson's personal designs and inventions, visit the Mr Carlson's Lab Patreon page here: www.patreon.com/MrCarlsonsLab
i looked for a way to contact you via a pm on youtube caint seem to find a way. i am interested in you building me a noise filter board to filter feedback from a fan i have installed in my audio receiver. i am wanting the board as small as possible which i caint do a printed circuit board like you do. i could be interested in multiple noise filter circuit boards as i dont keep my house cold usually around 85 - 90 degrees in summer time and i use older audio equipment thats better made then this newer stuff but it does seem to run hot and i can smell the hot electronics before i install cooling fans.
Amen, amen and AMEN! For I am a 45 yr instructor (retired now) teaching RCA (and other Co,s) technicians; on radios and TV's, etc. And Paul has shown me things I NEVER knew. And more than just one. He is a true "Genius of Genius's". And a true "Cut-Above". I believe he is the GREATEST electronic's teacher I've ever seen.
All of your videos are interesting Paul, but I think this is my favorite to date. All along the alignment I couldn't help wishing I could see how the alignment was done at the factory. Wouldn't that be fascinating! To see the gear they used and what sort of technicians did the procedure. Probably young ladies trained to do the work. I can dream... Thank you, Paul. Don't go away. I'd really miss your videos. 73, from Paul (me) K8IDX.
Many years ago in the U.S. Navy Sub electronics school, our instructor "CPO Ward" asked if anyone in the class had "Spectrophobia", no one even knew what that was, He went on to say it was fear of Ghosts, then he brought out the Spectrum Analyzer and proceeded to show us the alignment graphs and how they resembled the shape of Ghosts in a white sheet. LOl, I still chuckle at that!
Thank you Mr Carlson, we greatly appreciate your expertise. Your Video will help me when I go to sweep align a 1938 112 Trav-ler radio with a Broad - Narrow band pass switch. This I.F. alignment procedure of the RCA AR/CR-88 radios reminds me of the days when I did sweep alignment of TV I.F. and color I.F. back in the day when I did TV repair work. Getting the coils adjusted just right was tedious indeed and having patience.
Paul, it's a credit to the original designers, manufacturers and your restoration knowledge and skill that this radio seems so stable and, I'm sure, will match the performance of many current solid state units. I'm only sorry that I sold my AR88 back in 1973 😒
I don't have an AR-88, but I do have an R-390a can't wait to see how bad I screwed it up according to Mr Carlson. I will definitely be redoing the rebuild on the R-390a after his video restoration. Thank you Paul for all you do.
I would liked to have seen the IF response curves before you started. Would have been interesting to see how close or far off they were before you began. its just my way of seeing the improvements made. I've aligned many microwave band pass filters and yes it can be very tedious. Great series. Makes me want to go find one of these to play with.
I've really enjoyed this series. A lot to learn about these old receivers. The lab looks great! I really enjoy the layout of equipment on the bench. Looks like a busy city of sky scrapers of test equipment. Both eye pleasing and ergonomically convenient.
Mr C, you can move that camera as much as you want. Your ability to get your point across is greatly aided in the shots of the scope vs the control points you are adjusting! As always, informative, and interesting to watch! Keep it rockin, 73 de Pat KK6PD
Thank you for the great demonstration of sweep aligning a receiver. I have used sweep aligning for years on the commercial equipment that I serviced. Someone asked what the sweep rate was. I used to use 20Hz. This is a declining art as receivers are now all on one IC. This type of alignment is also critical on receivers handling video and data as proper bandwidth is necessary as much as amplitude. Again, great job and I appreciate your attention to detail.
When Mr. Carlson speaks - people listen! Paul, I am always in awe of your knowledge and skill. It's sad that very, very few young men are interesting this kind of work or hobby. It must have been a great time to be in the electronics field/hobby back in the 40s-50s-60s maybe even the 70s. Or, am I wrong in that thought?
Thanks to UA-cam there's been a surprisingly large recent growing interest in this and other vintage things. It's encouraging to see this stuff again grow in popularity, especially in the younger generations.
Paul very thankful to you for taking the time showing this alignment very helpful to the rest of Hams I will use your techniques on my Hammarlund receiver. Great to enjoy coffee and watch the best channel on You tube. Great Job Paul 73s Mike
Mr C. another great episode. "Almost there", well I'm certainly getting an education. The amount of time you spend off camera restoring these jewels must be staggering. With specialized test equipment and hours just aligning the IF section is amazing, makes me wonder how long it took the original factory folks to accomplish the task. Fantastic video as always, well done, thank you. 73, KC5NEX
Great video! For the benefit of those who are interpreting older manuals to adjust radios with newer equipment, could you comment briefly on the fact that often an oscilloscope was used in the "old days" - with a linear amplitude response as implied in the CR88 manual (pages 11-12) - whereas these days one might use a spectrum analyzer with a tracking generator - as you did. Specifically the fact that a "50%" amplitude at a given bandwidth when viewed as a *voltage* on an oscilloscope would represent a 6 dB *power* reduction on a spectrum analyzer when it is represented logarithmically - and when aspects of the circuit and where one monitors the signal may affect this interpretation? Thanks, and keep up the good work!
Brilliant engineer Mr Carlson sir. very very nice i really love your videos first thing is clearly shows you Electronic components how it works and which part is what's job this is really good sir you are awesome. Thanks for the sharing this video sir ❤❤
👍Thank you for another interesting episode. Yes, looking forward to hearing how this set performs on the air. I have a feeling it's going to be good. If you have a modern HF receiver or SDR to compare it against, that might be interesting.
I agree with the high DC voltages present in tube gear. I got zapped with 380VDC a while back now, a very stupid mistake, and I tell you, I felt funky for quite a while after!!
Maybe someday you can explain how the "sweeping" works. ie - How fast is the sweep, is there persistence involved, etc. Can sweeping happen too fast/slow? I haven't be able to wrap my head around how the swept response curve is shown in "real time". Great vid as always. 👍
This spectrum analyzer, and all modern spectrum analyzers, are based on microprocessor control and digital storage of the sweep data. The CRT continues to display the previous sweep trace (or older data) as a result of what was stored in digital memory while new sweep trace data overwrites it and updates the data. The display does not use persistence to hold the sweep trace. The spectrum analyzer was in continuous sweep mode so it sweeps and updates repeatedly. You can see the sweep time on the CRT display and the green flashing sweep LED for each new sweep. The sweep time is a function of the resolution bandwidth, sweep span, and other parameters. You don't just set a sweep time like you would on an oscilloscope. Don't forget, the spectrum analyzer is showing frequency and amplitude, not time and amplitude. The tracking generator output frequency matches the frequency of the sweep position at any given moment. Note that if you connect the tracking generator directly back to the analyzer input you will get a flat line sweep because the amplitude is the same at each frequency point.
Whenever you talk about CAPACITORS, it reminds me of an episode of the comedy show NewsRadio WNYX. In the episode, their TV has gone on the fritz, and Matthew (played by Andy Dick) says "Oh. I can fix that. My Dad showed me how. I'll just borrow your screwdriver, Joe." But Joe, the handyman (played by Joe Rogan) says "Watch out Matthew. There are capacitors in there" to which Matthew replies "Capacitors. Shapacitors. Who cares about capacitors", and proceeds to open the back of the TV. He then prods around inside with the screwdriver, and suddenly there is a mighty Zaaaappppp and Matthew emerges from behind the TV with his face blackened and his naturally wavy hair standing straight up on end. Hilarious :-) PS - Love your restoration adventures. Especially the capacitors. Cheers from Canada.
A lot of really useful information here and interesting how the technique differs from the normal. I wonder what test equipment was used in the factory back in the 40s; did they have anything like a spectrum analyser to align the sets?
Dear Mr Carlson, When you get to the RF alignment, I would be most interested to know how good the image rejection is at the higher frequencies. With an IF of 455kHz, the image will be only 910kHz away from the tuned frequency. Even with 3 preselector tuned circuits, I doubt if it will be better than 20dB at 30MHz. The disadvantages of singe conversion led to double conversion receivers, and eventually to up conversion receivers where the first IF was above the tuning range. Also of interest would be a measurement of third order intermodulation , as a test of linearity. I would expect a valve ( tube to you) receiver to be quite good in this respect.
Just another idea I've had. I'm wondering how this could be done with "Tiny SA" or other less expensive test equipment. A lot of budget test equipment has come out in recent years and some of it has very decent results. Nano VNA also comes to mind. I know you build a lot of test equipment here and on Patreon and these designs replace equipment that costs thousands of dollars. Well worth the $2 to get the plans for. I have 4 pages of notes and a thumb drive worth of your Patreon material and it's a gold mine of information. A friend of mine who is now a silent key W4CWG worked for Bell Labs (Western Electric) as an engineer and designed a spectrum analyzer using the tuner out of a VCR. If you Google search this call sign you will find a web site of his crystal radio designs and test equipment which is a pretty good source of information. I would love to see a future video of you working with more of this less than perfect equipment. Thanks again for all you do!
Hey Paul. So, we're getting close now!! It will sound amazing. I have one question. What do you do with all the stuff you restore? Do you keep it all, or you sell some of it or you give it away to your family? Cheers
It would have been helpful if you had demonstrated how to do the IF alignment with just a sweep generator and scope as per the procedure in the manual. I doubt most watchers own the sophisticated generator/scope you used, but most would have a scope and sweep generator.
This is exactly the same process that color tv techs had to go through. The main exception being that color tvs also had at least a couple of traps to set and usually only three IF stages.
I still would like to see session with the Cp;;oms 75A4! in metro areas with highly crowded users, the Collins 75A4 for those fortunate to be able to afford to own one would find that the mechanical filter selectivity would make a huge difference in amateur radio enjoyment! Maybe the Watkins-Johnson receiver with its use of DSP would provide comparable or even superior results in congested band areas but at a more affordable price!
Not too sure what alignment papers you are using, but if they are graphed in Voltage, then 50% down will be at the -6dB location on your logarithmic scale Spectrum Analyser.
Hello Mr. Carlson, thank you for this excellent video. I've got a question for you .. this adjustments could have been done with a VNA instead of a tracking generator and a spectrum analyzer?
Paul, you are using your White box SA protection boxes, the ones you have used in other older videos, & shown their construction. You built them for use on high-impedance Tracking Generator & SA inputs, and said in passing 'these could easily be modified for 50 ohm inputs', and left it at that. Having not much knowledge of rf design, could you elaborate on how to construct one for use on 50 ohm? That would be greatly appreciated.
Hi Mr Carlson, I have a AR88 RCA Receiver used by my late father for Ham operation callsign VU2VU, I would like to restore it someday, is the tubes and parts available and any pointers to some sources. Apricate your effort for explaining the IF alignment procedure. What the basic equipment required for restoring the receiver?
Mr Carlson. I am going to be doing one of these as soon as it arrives form Canada and will end up having to eventually do the alignment. I do no have the type of equipment that you do and I have watched both Gerry O'harra's and your videos on doing this. I also have an older ham buddy up in Canada that had done quite a few of these sets without the high end equipment. What I do have is a new Rigol 2 chanel 100 MHz digital scope, a Fordham 2Mhz sweep function generator, a regular signal generator and a digital frequency counter. Do you think I should be able top preform a proper alignment with this equipment? This will be o course after cleaning up and recapping the radio.
That sensation of being grabbed and shaken by a gorilla when you inadvertently touch an "elevated voltage" point, is what scares the hell out of me with these things.
Does your SA have an input jack to add additional markers? I would like to do a color tv IF alignment with a SA while coupling in crystal markers from my B&K 415 .
Just curious -- on the diagrams, the IF selectivity curves indicated the 10kHz, 8kHz and 14kHz bandwidths at 50% (-6dB), but alignment was at -3dB. Am I misunderstanding something?
Hi Jim. Perfectly valid question. I experimented with both the 3 db down points (most common for IF alignment,) and also the 6 db down points. After verification that all stages were operating correctly, I fed the last IF stage (4th IF or T9) with a sweep (from the tracking generator) and monitored its output. It was "impossible" to get 10 kc's width at 455 kHz at 6 dB down. The closest it would come was "very close to" 15 kHz at 6 db down, and off center frequency, IE: not at the 455 kHz center. (Keep in mind: All stages are working perfectly.) After trying every slug position, (lots of twisting!) I began to experiment with the more common 3 db down points, (which makes more sense anyways.) I was able to come in at 10 kc's width at 455 kHz, "and not by much either!" The rest of the transformers exhibit much of the same characteristics as the 4th IF, especially when trying to get two response patterns out of one set of adjustments. So after hours of experimentation, 3 db it is! I'm impressed that you recognized the 50% notation in the paperwork, and also noticed I used 3 db! For those that want to know: ( -3 db = .5 "Power ratio") and (-3 db = .7 "Voltage ratio.") Where (-6 db = .25 "Power ratio") and (-6 db = .5 "Voltage ratio.")
@@MrCarlsonsLab Thank you for the explanation. I suspected that the -6dB might be wishful thinking on their part. That would be hella selective tuning, though! Great video as always, sir. Back to lurking... *lurk*
Regarding the diagram for the 2nd and 3rd Stage, should the -3dB point not always be measured from the top, not the center of the graph? Otherwise it makes no sense to have only one bandwidth line in a diagram with two very different waveforms.
It would be interesting to see the effect of these little adjustments on a real world signal. I wonder how a little change in the IF response shape would affect actual use. I would guess on a signal of reasonable strength and quality not much. What an engineering marvel for its day. They would have loved to have a spectrum analyzer like yours. Fuel tanks have capacity capacitors don't. Capacitors have capacitance. Common mistake lets not spread it.
The alignment instructions show the bandwidth measuring points at 50% and you used the 3dB down points for this which is the 50% POWER levels but shouldn't this be adjusted at the 50% VOLTAGE levels which is 6dB down?
Water, or nothing at all. Even then you've got to be careful. I've neatly cleaned the word "Admiral" off a 1950's tube before using nothing but a water dampened paper towel!
Would have been better to use test equipment of the time . A number of subscribers may not have access to a spectrum analyzer and tracking generator. Also would be nice to have a comparison of using some type of peak method vs this more comprehensive method if we have no choice.
Unfortunately, this is one of those jobs that can only be performed correctly using a swept input and a visual representation of the output response. AR-88s were probably factory aligned using a scope and wobbulator, a 1940s combination equivalent to a crude spectrum analyzer. "Receivers aligned by any other method, when checked on an oscilloscope, have shown some remarkable instances of misalignment not easy to detect in any other way." - "Getting the Utmost from the AR88", W. K. Miller (G6QF), Short Wave Magazine, April 1953 If you don't have a spectrum analyzer, a "poor man's SA" can be cobbled together using a scope in X-Y mode, a ramp generator, and a sine generator with VCG input. This is the equivalent of a scope & wobbulator, and while setup is more difficult, and results may not be as good as with a real SA, they're probably good enough for this vintage equipment.
I said this about the radio with a really fancy dial. I really don’t think the amount of gain in each of these settings is the point. When you first started the alignment of that previous radio much like all the other radios you’ve worked on I’m sure it was close in alignment. They went from very narrow to a very wide flat curve. Giving you options in the amount of bandwidth you’re picking up. By tuning all of this to a high gain all that’s going to really do is make it so you can keep the volume lower than you need to. There appears to be so much more in terms of amplification available. It’s not even going to be used. I have zero electronics experience or training and the only thing I can think of about what we’re doing here is those old periscope videos about how radios work. The way in and which you pick out the radio frequency you want to listen to from all the other frequencies. Maybe I’m wrong but on the other radio, there’s no reason to change it from the three-quarter position you have it on. There should be just different selections of the amount of band with you want and it looks like on those instruction sheets They’re not even asking you to achieve certain gain levels. I really feel Like you’re approaching us like a muscle car and trying to get the most power instead of the cleanest signal. I guarantee you can achieve those curves correctly if you lower the gain.
Thats not how it works. When tuning the IF section, you sacrifice gain for bandwidth, or bandwidth for gain, this is the reason they have 4 IF stages in this receiver. When you tune for width, you loose height. If I was to lower the gain, I would gain more width, and therefore have a broader response pattern. A broader response pattern will decrease the selectivity. They don't leave much room, either you get it right, or you have the lack of one or the other. If you want to lower the overall gain, this is done with the RF gain control, not by mis-aligning or detuning the IF section.
I am struggling to understand after ten minutes. I am waiting for you to say that the generator output has to be much bigger than the signal from the still connected previous i/f stages so that it swamps it out so that it doesn't interfere with the measurements. Am I correct in that? Assuming that there is no RF input, what comes through from previous stages will be white noise, but modified to have peak amplitude around the i/f frequency of the previous stages. If the signal generator has a much lower output impedance than the previous i/f tube it will override the noise. Maybe I shouldn't comment so early in the video. Edit: just realized the tubes are upside down on the schematic. Much easier to see pin 4 is the grid when you notice that!
I have a Collins 51J-4 - have the original manual which goes into detail on alignment. What I don't have is an HP 3585B! They are excessively expensive for a cheapskate part time winter only hobbyist such as myself. The receiver works very well apart from some "features" (see later) - it's incredibly accurate on frequency. However eventually I want to return the 51J-4 back to its original non-descriminator SSB system - mine has the "Hollow State Newsletter" mods by Dallas Lankford which seem to be improperly modded on my example - looks a mess and totally disables the meter on the higher frequency bands - seems also to render the RF gain control mostly useless - eg. if you decrease RF gain the meter goes up! Am guessing that's not the way it's supposed to work. Anyway - I'm getting away from the point - what sort of cheapskate sweep generators and frequency analysers are up to the sort of alignment you show here? I do have a OWON 25Mhz USB oscilloscope with a pretty basic FFA.
Pretty tedious. I wonder what service would have cost back in the day. Imagine at today's shop rate of $100/hr what this radio would cost to go through. Comparing apples and oranges I suppose. You spent a LOT for technology back then and you wanted to keep it in good shape. My parent's first color TV bought in 1968 that cost around $400 would be $3500 in today's $. Now you can buy a TV for $150 that would be like $17 in 1968 $ BUT it is virtually unrepairable.
Great Video now I can go out and find one of these ultra rare receivers and spend 10 of thousands of dollars on test equipment to listen to staticky Mexican radio . Awesome such a useful video thank you
Many people own these receivers, and there are no alignment videos created to date that display this technique, so you are correct, this video will be useful to a lot of people. Your over exaggeration is amusing as well.
@@stevencraig No Salt its just that someone with his troubleshooting skills could be teaching so much more rather than wasting his valuable time on showing how to IF align a radio that 6 people own and 2 of then use with test gear only he would own . I get its his channel and can do what he wants but with no feedback he is in a bubble and to answer your next comment I was not being rude you are just being over sensitive . And while its true his melodious voice puts me to sleep so well its nice to learn something useful if your gonna spend 45 minutes watching .OK FEEL better now ?
Just so you know Alex, UA-cam is putting your comments into a review folder automatically. I have to release these to make them public. You see them as public on your end, but no one else does. This is probably due to your negative comment history. Just a heads up to be a nicer person.
To learn electronics in a very different and effective way, and gain access to Mr Carlson's personal designs and inventions, visit the Mr Carlson's Lab Patreon page here: www.patreon.com/MrCarlsonsLab
Been waiting almost a year for an interesting project.
i looked for a way to contact you via a pm on youtube caint seem to find a way. i am interested in you building me a noise filter board to filter feedback from a fan i have installed in my audio receiver. i am wanting the board as small as possible which i caint do a printed circuit board like you do. i could be interested in multiple noise filter circuit boards as i dont keep my house cold usually around 85 - 90 degrees in summer time and i use older audio equipment thats better made then this newer stuff but it does seem to run hot and i can smell the hot electronics before i install cooling fans.
I thought I knew quite a lot about working on vintage radios until I found this channel !!! Huge respect sir . Regards from the UK .
Amen, amen and AMEN! For I am a 45 yr instructor (retired now) teaching RCA (and other Co,s) technicians; on radios and TV's, etc. And Paul has shown me things I NEVER knew. And more than just one. He is a true "Genius of Genius's". And a true "Cut-Above".
I believe he is the GREATEST electronic's teacher I've ever seen.
So early my capacitors are still reforming under the dulcet tones of Mr. Carlson .
Mr Carlsons lab you are good at restoring vintage shortwave receivers and alignment of vintage shortwave receivers 🎉🎉🎉😊🎉
A better question for him would be, what aren't you good at as far as electronics go!
That locknut wrench is pretty obscure.....naturally you have one! Fantastic what can be done with the proper gear. Thank you, Paul!
All of your videos are interesting Paul, but I think this is my favorite to date. All along the alignment I couldn't help wishing I could see how the alignment was done at the factory. Wouldn't that be fascinating! To see the gear they used and what sort of technicians did the procedure. Probably young ladies trained to do the work. I can dream... Thank you, Paul. Don't go away. I'd really miss your videos. 73, from Paul (me) K8IDX.
Thank You for your kind comment Paul!
Very well said, Paul!
Many years ago in the U.S. Navy Sub electronics school, our instructor "CPO Ward" asked if anyone in the class had "Spectrophobia", no one even knew what that was, He went on to say it was fear of Ghosts, then he brought out the Spectrum Analyzer and proceeded to show us the alignment graphs and how they resembled the shape of Ghosts in a white sheet. LOl, I still chuckle at that!
It probably never had an alignment this correctly since it left RCA. Great video Paul.
Thank you Mr Carlson, we greatly appreciate your expertise. Your Video will help me when I go to sweep align a 1938 112 Trav-ler radio with a Broad - Narrow band pass switch. This I.F. alignment procedure of the RCA AR/CR-88 radios reminds me of the days when I did sweep alignment of TV I.F. and color I.F. back in the day when I did TV repair work. Getting the coils adjusted just right was tedious indeed and having patience.
Paul, it's a credit to the original designers, manufacturers and your restoration knowledge and skill that this radio seems so stable and, I'm sure, will match the performance of many current solid state units. I'm only sorry that I sold my AR88 back in 1973 😒
I don't have an AR-88, but I do have an R-390a can't wait to see how bad I screwed it up according to Mr Carlson. I will definitely be redoing the rebuild on the R-390a after his video restoration. Thank you Paul for all you do.
I would liked to have seen the IF response curves before you started. Would have been interesting to see how close or far off they were before you began. its just my way of seeing the improvements made. I've aligned many microwave band pass filters and yes it can be very tedious. Great series. Makes me want to go find one of these to play with.
To a layman like myself, this is very akin to the technical jargon overload video. However Mr.Carlson's lab is quite pleasant to fall asleep to :)
I've really enjoyed this series. A lot to learn about these old receivers. The lab looks great! I really enjoy the layout of equipment on the bench. Looks like a busy city of sky scrapers of test equipment. Both eye pleasing and ergonomically convenient.
Mr C, you can move that camera as much as you want. Your ability to get your point across is greatly aided in the shots of the scope vs the control points you are adjusting! As always, informative, and interesting to watch! Keep it rockin, 73 de Pat KK6PD
Mr Carlsons lab your utube videos are awesome 👌 👏 👍 😊
Thank you for the great demonstration of sweep aligning a receiver. I have used sweep aligning for years on the commercial equipment that I serviced. Someone asked what the sweep rate was. I used to use 20Hz. This is a declining art as receivers are now all on one IC. This type of alignment is also critical on receivers handling video and data as proper bandwidth is necessary as much as amplitude.
Again, great job and I appreciate your attention to detail.
I stand by my previous statement.
The man can see electrons move about. If I knew what he forgot, I would be a genius.
Grazie Mr Carlson per questa stupenda lezione di radiotecnica !
When Mr. Carlson speaks - people listen! Paul, I am always in awe of your knowledge and skill. It's sad that very, very few young men are interesting this kind of work or hobby. It must have been a great time to be in the electronics field/hobby back in the 40s-50s-60s maybe even the 70s. Or, am I wrong in that thought?
Thanks to UA-cam there's been a surprisingly large recent growing interest in this and other vintage things. It's encouraging to see this stuff again grow in popularity, especially in the younger generations.
In industry, a lot of young women have filled the places left vacant by young men with no interest in electronics! :)
@@mikebarrett2621 It's sad that all that most people seem to care about the mind micro controller they carry around with them.
I know little of this but thanks for keeping this technology alive!
Paul very thankful to you for taking the time showing this alignment very helpful to the rest of Hams I will use your techniques on my Hammarlund receiver. Great to enjoy coffee and watch the
best channel on You tube. Great Job Paul 73s
Mike
Lovely evenings viewing
Mr C. another great episode. "Almost there", well I'm certainly getting an education. The amount of time you spend off camera restoring these jewels must be staggering. With specialized test equipment and hours just aligning the IF section is amazing, makes me wonder how long it took the original factory folks to accomplish the task. Fantastic video as always, well done, thank you. 73, KC5NEX
Very well done Paul, that alignment came out excellent. Cheers,
Great video!
For the benefit of those who are interpreting older manuals to adjust radios with newer equipment, could you comment briefly on the fact that often an oscilloscope was used in the "old days" - with a linear amplitude response as implied in the CR88 manual (pages 11-12) - whereas these days one might use a spectrum analyzer with a tracking generator - as you did.
Specifically the fact that a "50%" amplitude at a given bandwidth when viewed as a *voltage* on an oscilloscope would represent a 6 dB *power* reduction on a spectrum analyzer when it is represented logarithmically - and when aspects of the circuit and where one monitors the signal may affect this interpretation?
Thanks, and keep up the good work!
Brilliant engineer Mr Carlson sir. very very nice i really love your videos first thing is clearly shows you
Electronic components how it works and which part is what's job this is really good sir you are awesome. Thanks for the sharing this video sir ❤❤
Excellent video. I hope you go through an R388 sometime in the future. It seemed to be about King when it came to freq stability.
👍Thank you for another interesting episode. Yes, looking forward to hearing how this set performs on the air. I have a feeling it's going to be good. If you have a modern HF receiver or SDR to compare it against, that might be interesting.
I agree with the high DC voltages present in tube gear. I got zapped with 380VDC a while back now, a very stupid mistake, and I tell you, I felt funky for quite a while after!!
Maybe someday you can explain how the "sweeping" works. ie - How fast is the sweep, is there persistence involved, etc. Can sweeping happen too fast/slow? I haven't be able to wrap my head around how the swept response curve is shown in "real time". Great vid as always. 👍
This spectrum analyzer, and all modern spectrum analyzers, are based on microprocessor control and digital storage of the sweep data. The CRT continues to display the previous sweep trace (or older data) as a result of what was stored in digital memory while new sweep trace data overwrites it and updates the data. The display does not use persistence to hold the sweep trace. The spectrum analyzer was in continuous sweep mode so it sweeps and updates repeatedly. You can see the sweep time on the CRT display and the green flashing sweep LED for each new sweep. The sweep time is a function of the resolution bandwidth, sweep span, and other parameters. You don't just set a sweep time like you would on an oscilloscope. Don't forget, the spectrum analyzer is showing frequency and amplitude, not time and amplitude. The tracking generator output frequency matches the frequency of the sweep position at any given moment. Note that if you connect the tracking generator directly back to the analyzer input you will get a flat line sweep because the amplitude is the same at each frequency point.
Ahhh! Now I get it. Thanx EEWB.
Nice Receiver! My father really like this radio! PushPull 6v6 Audio!
I would love to see how this set was aligned on the assembly line! Quite time consuming!
Well I’ll be a Carlson video I missed .
Whenever you talk about CAPACITORS, it reminds me of an episode of the comedy show NewsRadio WNYX. In the episode, their TV has gone on the fritz, and Matthew (played by Andy Dick) says "Oh. I can fix that. My Dad showed me how. I'll just borrow your screwdriver, Joe." But Joe, the handyman (played by Joe Rogan) says "Watch out Matthew. There are capacitors in there" to which Matthew replies "Capacitors. Shapacitors. Who cares about capacitors", and proceeds to open the back of the TV. He then prods around inside with the screwdriver, and suddenly there is a mighty Zaaaappppp and Matthew emerges from behind the TV with his face blackened and his naturally wavy hair standing straight up on end. Hilarious :-)
PS - Love your restoration adventures. Especially the capacitors. Cheers from Canada.
5:19 - 6:19 - Whiteboard and markers would visualize better than hands in the air :D
A lot of really useful information here and interesting how the technique differs from the normal. I wonder what test equipment was used in the factory back in the 40s; did they have anything like a spectrum analyser to align the sets?
Highly interesting. Thanks, Paul.
Patience & perseverance is essential.
Great series Professor Carlson !!
Dear Mr Carlson,
When you get to the RF alignment, I would be most interested to know how good the image rejection is at the higher frequencies.
With an IF of 455kHz, the image will be only 910kHz away from the tuned frequency. Even with 3 preselector tuned circuits, I doubt if it will be better than 20dB at 30MHz.
The disadvantages of singe conversion led to double conversion receivers, and eventually to up conversion receivers where the first IF was above the tuning range.
Also of interest would be a measurement of third order intermodulation , as a test of linearity. I would expect a valve ( tube to you) receiver to be quite good in this respect.
Just another idea I've had. I'm wondering how this could be done with "Tiny SA" or other less expensive test equipment. A lot of budget test equipment has come out in recent years and some of it has very decent results. Nano VNA also comes to mind. I know you build a lot of test equipment here and on Patreon and these designs replace equipment that costs thousands of dollars. Well worth the $2 to get the plans for. I have 4 pages of notes and a thumb drive worth of your Patreon material and it's a gold mine of information. A friend of mine who is now a silent key W4CWG worked for Bell Labs (Western Electric) as an engineer and designed a spectrum analyzer using the tuner out of a VCR. If you Google search this call sign you will find a web site of his crystal radio designs and test equipment which is a pretty good source of information. I would love to see a future video of you working with more of this less than perfect equipment. Thanks again for all you do!
Hey Paul. So, we're getting close now!! It will sound amazing. I have one question. What do you do with all the stuff you restore? Do you keep it all, or you sell some of it or you give it away to your family? Cheers
Hi Nelson. All of the above.
It would have been helpful if you had demonstrated how to do the IF alignment with just a sweep generator and scope as per the procedure in the manual. I doubt most watchers own the sophisticated generator/scope you used, but most would have a scope and sweep generator.
This is exactly the same process that color tv techs had to go through. The main exception being that color tvs also had at least a couple of traps to set and usually only three IF stages.
I still would like to see session with the Cp;;oms 75A4! in metro areas with highly crowded users, the Collins 75A4 for those fortunate to be able to afford to own one would find that the mechanical filter selectivity would make a huge difference in amateur radio enjoyment! Maybe the Watkins-Johnson receiver with its use of DSP would provide comparable or even superior results in congested band areas but at a more affordable price!
Not too sure what alignment papers you are using, but if they are graphed in Voltage, then 50% down will be at the -6dB location on your logarithmic scale Spectrum Analyser.
going to be better than new
The alignment that separates the men from the boys, as the farmers in Montana used to say.
Hello Mr. Carlson, thank you for this excellent video. I've got a question for you .. this adjustments could have been done with a VNA instead of a tracking generator and a spectrum analyzer?
What is the expected sensitivity in micro-volts for each band setting?
If you want to work that out, they have provided gain measurements in the manual.
Paul, you are using your White box SA protection boxes, the ones you have used in other older videos, & shown their construction. You built them for use on high-impedance Tracking Generator & SA inputs, and said in passing 'these could easily be modified for 50 ohm inputs', and left it at that. Having not much knowledge of rf design, could you elaborate on how to construct one for use on 50 ohm? That would be greatly appreciated.
Hi Mr Carlson, I have a AR88 RCA Receiver used by my late father for Ham operation callsign VU2VU, I would like to restore it someday, is the tubes and parts available and any pointers to some sources. Apricate your effort for explaining the IF alignment procedure. What the basic equipment required for restoring the receiver?
Around 7:10 you mention "the diode output line" -> is the "diode" the tube in the extreme upper right of the schematic?
Yes, that detector and AVC tube is one of the two little stubby looking tubes on the chassis, the other 6H6 beside it is the noise limiter tube.
@@MrCarlsonsLab thank you, Mr Carlson!
Mr Carlson. I am going to be doing one of these as soon as it arrives form Canada and will end up having to eventually do the alignment. I do no have the type of equipment that you do and I have watched both Gerry O'harra's and your videos on doing this. I also have an older ham buddy up in Canada that had done quite a few of these sets without the high end equipment. What I do have is a new Rigol 2 chanel 100 MHz digital scope, a Fordham 2Mhz sweep function generator, a regular signal generator and a digital frequency counter. Do you think I should be able top preform a proper alignment with this equipment? This will be o course after cleaning up and recapping the radio.
That sensation of being grabbed and shaken by a gorilla when you inadvertently touch an "elevated voltage" point, is what scares the hell out of me with these things.
That's a very good description! It's somewhat like that.
Does your SA have an input jack to add additional markers? I would like to do a color tv IF alignment with a SA while coupling in crystal markers from my B&K 415 .
thank you
Just curious -- on the diagrams, the IF selectivity curves indicated the 10kHz, 8kHz and 14kHz bandwidths at 50% (-6dB), but alignment was at -3dB. Am I misunderstanding something?
Hi Jim. Perfectly valid question. I experimented with both the 3 db down points (most common for IF alignment,) and also the 6 db down points. After verification that all stages were operating correctly, I fed the last IF stage (4th IF or T9) with a sweep (from the tracking generator) and monitored its output. It was "impossible" to get 10 kc's width at 455 kHz at 6 dB down. The closest it would come was "very close to" 15 kHz at 6 db down, and off center frequency, IE: not at the 455 kHz center. (Keep in mind: All stages are working perfectly.) After trying every slug position, (lots of twisting!) I began to experiment with the more common 3 db down points, (which makes more sense anyways.) I was able to come in at 10 kc's width at 455 kHz, "and not by much either!" The rest of the transformers exhibit much of the same characteristics as the 4th IF, especially when trying to get two response patterns out of one set of adjustments. So after hours of experimentation, 3 db it is! I'm impressed that you recognized the 50% notation in the paperwork, and also noticed I used 3 db! For those that want to know: ( -3 db = .5 "Power ratio") and (-3 db = .7 "Voltage ratio.") Where (-6 db = .25 "Power ratio") and (-6 db = .5 "Voltage ratio.")
@@MrCarlsonsLab Thank you for the explanation. I suspected that the -6dB might be wishful thinking on their part. That would be hella selective tuning, though! Great video as always, sir. Back to lurking... *lurk*
Regarding the diagram for the 2nd and 3rd Stage, should the -3dB point not always be measured from the top, not the center of the graph? Otherwise it makes no sense to have only one bandwidth line in a diagram with two very different waveforms.
It would be interesting to see the effect of these little adjustments on a real world signal. I wonder how a little change in the IF response shape would affect actual use. I would guess on a signal of reasonable strength and quality not much. What an engineering marvel for its day. They would have loved to have a spectrum analyzer like yours.
Fuel tanks have capacity capacitors don't. Capacitors have capacitance. Common mistake lets not spread it.
The alignment instructions show the bandwidth measuring points at 50% and you used the 3dB down points for this which is the 50% POWER levels but shouldn't this be adjusted at the 50% VOLTAGE levels which is 6dB down?
Whats the noise on either side of the trace for IF section 1?
Remember the entire radio is working, and it is trying to receive while this alignment is being done.
Question, I have aquired a KG-625. It is extremely dirty. What do I use to clean it without the possibility of destroying the print on the face plate
Water, or nothing at all. Even then you've got to be careful. I've neatly cleaned the word "Admiral" off a 1950's tube before using nothing but a water dampened paper towel!
How far out was it when you started?
I noticed the right hand pilot bulb is flicking you have a bad connection somewhere.
just noticed at 22:01, when your showing your tie point, there is an orange cap with an open end. will that not affect your testing ???
Not at all.
Would have been better to use test equipment of the time . A number of subscribers may not have access to a spectrum analyzer and tracking generator. Also would be nice to have a comparison of using some type of peak method vs this more comprehensive method if we have no choice.
Unfortunately, this is one of those jobs that can only be performed correctly using a swept input and a visual representation of the output response. AR-88s were probably factory aligned using a scope and wobbulator, a 1940s combination equivalent to a crude spectrum analyzer. "Receivers aligned by any other method, when checked on an oscilloscope, have shown some remarkable instances of misalignment not easy to detect in any other way." - "Getting the Utmost from the AR88", W. K. Miller (G6QF), Short Wave Magazine, April 1953
If you don't have a spectrum analyzer, a "poor man's SA" can be cobbled together using a scope in X-Y mode, a ramp generator, and a sine generator with VCG input. This is the equivalent of a scope & wobbulator, and while setup is more difficult, and results may not be as good as with a real SA, they're probably good enough for this vintage equipment.
I said this about the radio with a really fancy dial. I really don’t think the amount of gain in each of these settings is the point.
When you first started the alignment of that previous radio much like all the other radios you’ve worked on I’m sure it was close in alignment. They went from very narrow to a very wide flat curve. Giving you options in the amount of bandwidth you’re picking up.
By tuning all of this to a high gain all that’s going to really do is make it so you can keep the volume lower than you need to.
There appears to be so much more in terms of amplification available. It’s not even going to be used.
I have zero electronics experience or training and the only thing I can think of about what we’re doing here is those old periscope videos about how radios work. The way in and which you pick out the radio frequency you want to listen to from all the other frequencies.
Maybe I’m wrong but on the other radio, there’s no reason to change it from the three-quarter position you have it on. There should be just different selections of the amount of band with you want and it looks like on those instruction sheets They’re not even asking you to achieve certain gain levels.
I really feel Like you’re approaching us like a muscle car and trying to get the most power instead of the cleanest signal. I guarantee you can achieve those curves correctly if you lower the gain.
Thats not how it works. When tuning the IF section, you sacrifice gain for bandwidth, or bandwidth for gain, this is the reason they have 4 IF stages in this receiver. When you tune for width, you loose height. If I was to lower the gain, I would gain more width, and therefore have a broader response pattern. A broader response pattern will decrease the selectivity. They don't leave much room, either you get it right, or you have the lack of one or the other. If you want to lower the overall gain, this is done with the RF gain control, not by mis-aligning or detuning the IF section.
"Not for the faint of heart!" Those coil forms have some very brittle slugs and coil forms that can lead to some misery! Just a warning to the wise!!
I am struggling to understand after ten minutes. I am waiting for you to say that the generator output has to be much bigger than the signal from the still connected previous i/f stages so that it swamps it out so that it doesn't interfere with the measurements. Am I correct in that? Assuming that there is no RF input, what comes through from previous stages will be white noise, but modified to have peak amplitude around the i/f frequency of the previous stages. If the signal generator has a much lower output impedance than the previous i/f tube it will override the noise. Maybe I shouldn't comment so early in the video. Edit: just realized the tubes are upside down on the schematic. Much easier to see pin 4 is the grid when you notice that!
Brasil
I have a Collins 51J-4 - have the original manual which goes into detail on alignment. What I don't have is an HP 3585B! They are excessively expensive for a cheapskate part time winter only hobbyist such as myself. The receiver works very well apart from some "features" (see later) - it's incredibly accurate on frequency. However eventually I want to return the 51J-4 back to its original non-descriminator SSB system - mine has the "Hollow State Newsletter" mods by Dallas Lankford which seem to be improperly modded on my example - looks a mess and totally disables the meter on the higher frequency bands - seems also to render the RF gain control mostly useless - eg. if you decrease RF gain the meter goes up! Am guessing that's not the way it's supposed to work. Anyway - I'm getting away from the point - what sort of cheapskate sweep generators and frequency analysers are up to the sort of alignment you show here? I do have a OWON 25Mhz USB oscilloscope with a pretty basic FFA.
How to spell alignment: Patience !
Better to buy a new radio, than to have to do this alignment.
Pretty tedious. I wonder what service would have cost back in the day. Imagine at today's shop rate of $100/hr what this radio would cost to go through. Comparing apples and oranges I suppose. You spent a LOT for technology back then and you wanted to keep it in good shape. My parent's first color TV bought in 1968 that cost around $400 would be $3500 in today's $. Now you can buy a TV for $150 that would be like $17 in 1968 $ BUT it is virtually unrepairable.
Great Video now I can go out and find one of these ultra rare receivers and spend 10 of thousands of dollars on test equipment to listen to staticky Mexican radio . Awesome such a useful video thank you
Many people own these receivers, and there are no alignment videos created to date that display this technique, so you are correct, this video will be useful to a lot of people. Your over exaggeration is amusing as well.
@@MrCarlsonsLab 3 People does not make a Many But I am sure those three people will appreciate it .
@alexkay1874 why so salty?
@@stevencraig No Salt its just that someone with his troubleshooting skills could be teaching so much more rather than wasting his valuable time on showing how to IF align a radio that 6 people own and 2 of then use with test gear only he would own . I get its his channel and can do what he wants but with no feedback he is in a bubble and to answer your next comment I was not being rude you are just being over sensitive . And while its true his melodious voice puts me to sleep so well its nice to learn something useful if your gonna spend 45 minutes watching .OK FEEL better now ?
Just so you know Alex, UA-cam is putting your comments into a review folder automatically. I have to release these to make them public. You see them as public on your end, but no one else does. This is probably due to your negative comment history. Just a heads up to be a nicer person.
Why did the police ask them to move nicely. They should have been manhandled by them then arrested for obstruction.
Please put a period "." after your handle "Mr". Thank you. (I'm a Capricorn. You know.)
I thought I knew quite a lot about working on vintage radios until I found this channel !!! Huge respect sir . Regards from the UK .
Thanks for your kind comment!