Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- TekScopes
- Messages
Search
Re: AM501 Stuff (op-amp references)
J Forster
From: "jones_chap" <jones_chap@...>
[snip] Interesting note about "anything with banana plugs" is that when playing around with the AM501 plugins was a sensitivity of the output based upon the proximity of my hand near the jacks. Wild and crazy things would happen as I got anywhere near 'em, sorta. One was much more sensitive than the other. The noise, etc. is capacitively coupled to your circuitry. Reduce the values of the components in the FB loop and it will go down or use a grounded aluminum foil shield. -John |
Re: First post - Hello and a question
arthurok
customer dosent want to pay for complicated
toggle quoted message
Show quoted text
----- Original Message -----
From: J Forster To: tekscopes Sent: Wednesday, February 07, 2007 5:39 PM Subject: Re: [TekScopes] First post - Hello and a question My late father used to say "Why do it simply, when complicated works well too" (It looses something in translation) He also said "An engineer can do for two cents what any fool can do for $10.00" 'nuff said, -John "DON CRAMER" wrote: Oh sure you would have done that in the old days. But perhaps Kuba is proposing that with today's open source calibration code for radio and audio alignment, running under Linux in a home brew digital scope, anyone would of course just dive in there and modify the.... Or have I missed the point entirely yet again, Kuba? Drat, I hate it when I do that. Tee-hee. Thanks for the fun. |
Re: AM501 Stuff (op-amp references)
jones_chap
Thanks. You beat me to the second question! I did wanna know if I
could "upgrade" knowing that better op-amps exist. I've downloaded the book and will check it out later and added the site to my Audio & Electronics Bookmarks. Interesting note about "anything with banana plugs" is that when playing around with the AM501 plugins was a sensitivity of the output based upon the proximity of my hand near the jacks. Wild and crazy things would happen as I got anywhere near 'em, sorta. One was much more sensitive than the other. Do ya have any recommendations for a replacement. I'd even be willing to spend more than the few cents that some of these cost--maybe even like $5--15 per chip! : ) Thanks again. |
Re: First post - Hello and a question
J Forster
Kuba Ober wrote:
> I guess for basic RF stage alignment you don't even need a scope, an RF RMS > voltmeter with a phase detector/indicator would probably suffice. I used > such a phase-indicating RF voltmeter back in high school to fix an ailing > RC receiver. It had a single mixer, an IF filter & amp, and it'd directly > demodulate the RF I mean IF of course. Kuba You don't NEED anything like an RF RMS voltmeter. or phase detector. A diode probe on a VTVM or very minimal scope will do just fine. You tune for the typical 'rabbit ears' [flat phase] response. Phase MIGHT be important in a wide band microwave communication system using BPSK or QPSK or NPSK, but not in audio gear. No way. -John |
Re: First post - Hello and a question
J Forster
My late father used to say "Why do it simply, when complicated works
well too" (It looses something in translation) He also said "An engineer can do for two cents what any fool can do for $10.00" 'nuff said, -John "DON CRAMER" wrote: Oh sure you would have done that in the old days. But perhaps Kuba is proposing that with today's open source calibration code for radio and audio alignment, running under Linux in a home brew digital scope, anyone would of course just dive in there and modify the.... Or have I missed the point entirely yet again, Kuba? Drat, I hate it when I do that. Tee-hee. Thanks for the fun. |
18000uf spague 15V
Charles A. Pratt
Hello,
Anyone have spares I have a way to test. I have three new 1000uf tabed radials that have been tested and work in 465M, and one old style 1000uf OEM tested. I also have one old style 18000uf tested good. I need either replacements for the one 18000uf NOS or new or a couple of old styles I can test. Thankyou for all the help the two 18000uf new I purchased off ebay turned out to be NG. I have access to a Sencor tester, willing to horse trade. Charles |
Re: First post - Hello and a question
Kuba Ober
On Wednesday 07 February 2007 16:49, you wrote:
Er, guys, do you even know what you're arguing about? The discussion hasOh sure you would have done that in the old days. But perhaps Kuba isI don't have the clue what you're talking about :( degenerated into everyone saying this: for a noob, buying an unknown 7603 and having no access to equipment to properly test its performance is good advice. Given that "random" mainframes and plugins can perform pretty wildly, and that a noob tends to believe what the screen shows, this is some bad advice really. The OP ("noob") says that he needs the scope for audio work (among other things). In audio work if you don't have other equipment such as distortion meters or spectrum analyzers, the main ways to "align" anything is to provide wideband square wave and tweak the stages till it looks right on the output. Or to provide a sine wave input, and also tweak till you're happy. If the scope does some of the things I had "random" 7603 + plugin combinations do, good luck getting anywhere. The noob may well get completely discouraged from furthering his/her interests. So: getting a 7603 is a good thing, as it's an investment that can be built on (more plugins) but it's a bad thing if you have nothing to at least partially test and calibrate it with. Apart from the 7603, some good probes would also be needed, especially for any RF tuning so that the probe doesn't detune the DUT. Kuba |
Re: First post - Hello and a question
Kuba Ober
I guess for basic RF stage alignment you don't even need a scope, an RF RMSI mean IF of course. Kuba |
Re: First post - Hello and a question
Kuba Ober
Oh sure you would have done that in the old days. But perhaps Kuba isI don't have the clue what you're talking about :( Kuba |
Re: First post - Hello and a question
Kuba Ober
I was talking about "aligning" audio circuits, e.g. adjusting operating Anyone who is at all capable of making those kind of measurementsThe input will look like a square wave even with a badly nonlinear vertical channel. The output "square" wave will then typically be much slower than the input one you fed to your system. With nonlinear vertical, the slower transitions on the output square wave will look distorted, and you may end up chasing ghosts, especially if the audio amp alignment procedure mentions e.g. "adjust Rxxx for output transitions to be smooth". I just don't believe in using unchecked instruments, and a reasonable way to check a 7603 with plugins is to use the classic calibration trio in a TM503, plus a mainframe standardizer. How on earth can anyone recommend using an unchecked, unknown scope to a newb is beyond me. Newbs tend to misunderstand limitations of instruments they use, so they are very likely to just blindly trust the trace, even if someone experienced would check things twice first. You know, things like using too much or too little of vertical deflection, not centering the signal and hunting differing rising/falling edge aberrations, and so on. It's just very easy to hit those on an uncalibrated scope methinks. Cheers, Kuba |
Re: First post - Hello and a question
Chuck Harris
Kuba Ober wrote:
Gee Kuba,Given that IIRC the OP doesn't have a spectrum analyzer, you'll want to Anyone who is at all capable of making those kind of measurements would surely measure the input square wave first. If it looks like a square wave, then the scope is good enough for the task. -Chuck Harris |
Re: First post - Hello and a question
Kuba Ober
On Wednesday 07 February 2007 13:56, you wrote:
Kuba Ober wrote:True, but given such a miscalibrated state, would you trust the instrument forKuba wrote:Kuba, anything serious? I guess for basic RF stage alignment you don't even need a scope, an RF RMS voltmeter with a phase detector/indicator would probably suffice. I used such a phase-indicating RF voltmeter back in high school to fix an ailing RC receiver. It had a single mixer, an IF filter & amp, and it'd directly demodulate the RF, if I remember things right. Due to vibration or whatnot the two little coupling transformers had the slugs at all the wrong places, and there was also a little air-wound coil with a couple turns that somehow got distorted (maybe someone played with it too much) and needed bringing back to shape. Being a total RF newb it took me a couple afternoons to figure it out, but in the end I had it working. I had a scope, but all I cared for was to get the response peak in the right place, and the voltmeter did just that, and the scope's probe seemed to load the circuit too much. The voltmeter had a couple different probes, two non-contact ones, and three contact ones. I don't remember their specs, though. You needed one probe for the voltmeter, and optionally another one for phase reference. For non-RF-alignment work, e.g. audio amplifier design/testing/adjustment, you will need to look at time-domain response, and for that you better had a scope that's linear in both X and Y subsystems. How can one just assume that it's the case with an unknown scope and not much to test it against?? Cheers, Kuba |
Re: First post - Hello and a question
Kuba Ober
Given that IIRC the OP doesn't have a spectrum analyzer, you'll want to Have you ever ACTUALLY aligned a receiver?I was talking about "aligning" audio circuits, e.g. adjusting operating points of various stages, checking response, etc. Not about any sort of RF work. If I wanted to see a nonlinearity of a stage in an audio power amp, for example, it'd be nice to believe that the scope's vertical system is linear enough, etc. Same goes for step response: hard to do with a scope that may well distort even a perfect square wave. Cheers, Kuba |
Re: First post - Hello and a question
J Forster
From: Kuba Ober
The original question was about a scope for audio and tuner alignment.Given that IIRC the OP doesn't have a spectrum analyzer, you'll want to get step or pulse responses of the audio gear you're testing. I can hardly see that going all too well with an uncalibrated scope. Audio "alignment" is essentially calibration work, and I can't see doing that with a scope that I know nothing about. Cheers, Kuba Have you ever ACTUALLY aligned a receiver? The most primitive scope suffices. A 503 is overkill. Suggesting that it's akin to calibration is audiophoolery. I guess you'd say you need a TDR to check your speaker wires too. All you have to do is get the IFs properly tuned (think diode probe flat from 10.6 to 10.8 MHz) and get the RF stage (if any) to track the oscillator properly. The trickiest part is the stereo circuitry and that requires a special generator. A decent generator is FAR more important than the scope. -John |
Re: First post - Hello and a question
Bill R
Kuba Ober wrote:
Kuba wrote:Kuba, The origin of many instruments on eBay are government surplus, or surplus acquired by someone with no calibration skills. In the first case, metrology (instrument calibration) technicians in gub ment would screw up an instrument they are trying to dump (or are instructed to do so) so it gets tagged "unusable". The other case results from uneducated people trying to fix something that ain't broke. Bill Roberts |
Re: First post - Hello and a question
Kuba Ober
A newbie may well not discern when someone is kidding and when not, andI'd rather think that advising a newbie to buy an uncalibrated, unknown 7603 is sending him/her on a wild goose chase. A newbie will not have enough experience to easily ascertain whether something is a scope issue or the DUT issue. Heck, I'd be uncomfortable using an off-eBay 7603 where all there is to test it out is a 1kHz calibrator square wave. Said newbie would do well to get some equipment to at least partially check out the 7603, which really means a TM503 loaded with the amplitude calibrator, time mark calibrator, and the levelled sine wave generator. Plus requisite plumbing and attenuators. That's really the most basic setup. And will cost approx. $500, depending on luck. The $1000 was a rough order of magnitude. Cheers, Kuba |
Re: First post - Hello and a question
Kuba Ober
The original question was about a scope for audio and tuner alignment.Given that IIRC the OP doesn't have a spectrum analyzer, you'll want to get step or pulse responses of the audio gear you're testing. I can hardly see that going all too well with an uncalibrated scope. Audio "alignment" is essentially calibration work, and I can't see doing that with a scope that I know nothing about. Cheers, Kuba |
Re: First post - Hello and a question
Kuba Ober
I would recommend the 7603 with a 7B53 Time Base and a couple of 7A18 Assuming you have approx. $1000 worth of other test equipment needed to NONSENSE: You can easily verify that a 7603 is basically working usingWell, if all you care about is *basically working*, then I agree. But then you don't need a 7603 either. A random 7603 with random plugins will *basically* work, but most of the time it doesn't really perform as a dependable 100MHz instrument. Maybe it's my luck, but 90% of the plugins that I bought in lots on eBay showed signs of being seriously miscalibrated, and two of my mainframes (7603 and a 7633) were quite miscalibrated as well; their pulse response was completely off limits and you need the standardizer for that. Cheers, Kuba |
Re: AM501 Stuff (op-amp references)
Kuba Ober
On Monday 05 February 2007 23:41, you wrote:
Beside collecting TM500 plugins, anyone actually usem, in particulars,Anything that has got banana jacks on it *may* perform poorly for anything above a few kilohertz due to parasitics, unless you put the feedback path next to the chip. It does have a place to solder components inside, BTW. The op-amp inside of AM501 can be replaced by a more modern chip, if you wish so. The plugin itself was designed for teaching op-amps, and has little utility beyond that methinks. For source of great op-amp circuits, download this *excellent* book: Applications Manual for Computing Amplifiers for Modeling, Measuring, Manipulating & Much Else. Then you'll want to get Troubleshooting Analog Circuits by Bob Pease, which has an excellent section on real life op-amp behavior. All in all, a good source of experimentation data is , which has tons of analog computation applications etc. Cheers, Kuba |
to navigate to use esc to dismiss