Scopes
Locked
 
|
I am thinking of getting a scope to better build and repair Elecraft radios.
I have a line on a Tektronix 2336YA 100 MHz 2 Chl. Oscilloscope that is calibrated! It is about $200. Is this a good deal? Is this a good scope? Thanks, Jack, AE6GC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
Jack, A36GC asked:
I am thinking of getting a scope to better build and repair Elecraft radios. I have a line on a Tektronix 2336YA 100 MHz 2 Chl. Oscilloscope that is calibrated! It is about $200. Is this a good deal? Is this a good scope? ----------------------------------- Teks are excellent scopes, overall. That's a very low price. The only caution I'll offer (and probably the reason for the low price) is the limited bandwidth. To observe signals accurately, a good rule is to have a 'scope that has a vertical bandwidth at least 10 times the highest frequency waveform you will be observing. That puts an upper useful frequency limit of about 10 MHz on that scope. It'll certainly show waveforms up to (and beyond) it's rated 100 MHz, but the amplifiers in the 'scope will "clean up" any aberrations in the waveform so you can't see what it really looks like. For example, if you put a square wave into the scope at 100 MHz, expect to see a nice, clean sine wave on the display! That's because a square wave has harmonics going up to at least 10 times the signal frequency, and unless your scope can faithfully reproduce those harmonics it won't show a very true representation of your signal. A 10 MHz square wave will look pretty accurate on the display since the 100 MHz bandwidth will handle all the harmonic energy needed to reproduce the signal. In the real world of working on HF gear, what such a scope will tend to do is to fail to display many high-frequency aberrations or parasitic riding on a lower-frequency signal, when those things are at or above the upper bandwidth limit. Also, the accuracy of the vertical amplifier "gain" (and so the accuracy of the amplitude of the trace on the display) suffers as you approach the veridical amplifier bandwidth specification. All that said, most adjustments needed on Amateur HF gear can be carried out at frequencies below 10 MHz, so that scope would find plenty of use on a Ham's workbench. I have a 200 MHz scope and only occasionally have to think about the bandwidth issue working on HF gear. Like any tool, understanding its limitations is as important as understanding its features. My 'scope is an HP, so I'll leave any suggestions about the value of that particular model to those here who follow the Tek scope line. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
I'll follow this thread with interest, as I too am considering a scope
purchase. I've heard comments such as Ron's before. I'm wondering if anyone has any thoughts on what bandwidth would be appropriate for "casual" use and what someone might expect to pay for a use one? Thanks in advance Tom wb2qdg k2 1103 ---------------------------------------------- Teamwork is a lot of people doing what I say. ----- Original Message ----- From: "Ron D'Eau Claire" <[hidden email]> To: "'Jack Regan'" <[hidden email]>; <[hidden email]> Sent: Friday, June 23, 2006 8:39 PM Subject: RE: [Elecraft] Scopes Jack, A36GC asked: I am thinking of getting a scope to better build and repair Elecraft radios. I have a line on a Tektronix 2336YA 100 MHz 2 Chl. Oscilloscope that is calibrated! It is about $200. Is this a good deal? Is this a good scope? ----------------------------------- Teks are excellent scopes, overall. That's a very low price. The only caution I'll offer (and probably the reason for the low price) is the limited bandwidth. To observe signals accurately, a good rule is to have a 'scope that has a vertical bandwidth at least 10 times the highest frequency waveform you will be observing. That puts an upper useful frequency limit of about 10 MHz on that scope. It'll certainly show waveforms up to (and beyond) it's rated 100 MHz, but the amplifiers in the 'scope will "clean up" any aberrations in the waveform so you can't see what it really looks like. For example, if you put a square wave into the scope at 100 MHz, expect to see a nice, clean sine wave on the display! That's because a square wave has harmonics going up to at least 10 times the signal frequency, and unless your scope can faithfully reproduce those harmonics it won't show a very true representation of your signal. A 10 MHz square wave will look pretty accurate on the display since the 100 MHz bandwidth will handle all the harmonic energy needed to reproduce the signal. In the real world of working on HF gear, what such a scope will tend to do is to fail to display many high-frequency aberrations or parasitic riding on a lower-frequency signal, when those things are at or above the upper bandwidth limit. Also, the accuracy of the vertical amplifier "gain" (and so the accuracy of the amplitude of the trace on the display) suffers as you approach the veridical amplifier bandwidth specification. All that said, most adjustments needed on Amateur HF gear can be carried out at frequencies below 10 MHz, so that scope would find plenty of use on a Ham's workbench. I have a 200 MHz scope and only occasionally have to think about the bandwidth issue working on HF gear. Like any tool, understanding its limitations is as important as understanding its features. My 'scope is an HP, so I'll leave any suggestions about the value of that particular model to those here who follow the Tek scope line. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
I have been using my Tek T935A (35 Mhz or thereabouts bandwidth) for all of
my design and troubleshooting and have never found it lacking. I have not yet needed it to analyse a 35 Mhz squarewave where much higher bandwidth would be needed to analyse waveshape. I have used it a lot on all kinds of boatanchor and modern digital projects (HF interest only, not VHF) and for casual use it is all I need. As an electronics engineer my career included a lot of lab time where high speed digital circuits required high bandwidth "glitch-catchers" as well as sophisticated triggering systems and storage capabilities that showed you what had been happening *before* the triggering. However, my ham radio interests have never demanded anything more than what I have. My experience is that reliable and *stable* triggering is just as important as bandwidth. Don K7FJ ----- Original Message ----- From: "Tom McCulloch" <[hidden email]> To: "Ron D'Eau Claire" <[hidden email]>; "'Jack Regan'" <[hidden email]>; <[hidden email]> Sent: Sunday, June 25, 2006 10:40 AM Subject: Re: [Elecraft] Scopes > I'll follow this thread with interest, as I too am considering a scope > purchase. > > I've heard comments such as Ron's before. I'm wondering if anyone has any > thoughts on what bandwidth would be appropriate for "casual" use and what > someone might expect to pay for a use one? > > Thanks in advance > Tom > wb2qdg > k2 1103 > > ---------------------------------------------- > > Teamwork is a lot of people doing what I say. > > > ----- Original Message ----- > From: "Ron D'Eau Claire" <[hidden email]> > To: "'Jack Regan'" <[hidden email]>; <[hidden email]> > Sent: Friday, June 23, 2006 8:39 PM > Subject: RE: [Elecraft] Scopes > > > Jack, A36GC asked: > > I am thinking of getting a scope to better build and repair Elecraft > radios. > I have a line on a Tektronix 2336YA 100 MHz 2 Chl. Oscilloscope that is > calibrated! It is about $200. Is this a good deal? Is this a good > scope? > > ----------------------------------- > > Teks are excellent scopes, overall. That's a very low price. The only > caution I'll offer (and probably the reason for the low price) is the > limited bandwidth. To observe signals accurately, a good rule is to have a > 'scope that has a vertical bandwidth at least 10 times the highest > frequency > waveform you will be observing. That puts an upper useful frequency limit > of > about 10 MHz on that scope. > > It'll certainly show waveforms up to (and beyond) it's rated 100 MHz, but > the amplifiers in the 'scope will "clean up" any aberrations in the > waveform > so you can't see what it really looks like. For example, if you put a > square > wave into the scope at 100 MHz, expect to see a nice, clean sine wave on > the > display! That's because a square wave has harmonics going up to at least > 10 > times the signal frequency, and unless your scope can faithfully reproduce > those harmonics it won't show a very true representation of your signal. A > 10 MHz square wave will look pretty accurate on the display since the 100 > MHz bandwidth will handle all the harmonic energy needed to reproduce the > signal. > > In the real world of working on HF gear, what such a scope will tend to do > is to fail to display many high-frequency aberrations or parasitic riding > on > a lower-frequency signal, when those things are at or above the upper > bandwidth limit. > > Also, the accuracy of the vertical amplifier "gain" (and so the accuracy > of > the amplitude of the trace on the display) suffers as you approach the > veridical amplifier bandwidth specification. > > All that said, most adjustments needed on Amateur HF gear can be carried > out > at frequencies below 10 MHz, so that scope would find plenty of use on a > Ham's workbench. I have a 200 MHz scope and only occasionally have to > think > about the bandwidth issue working on HF gear. Like any tool, understanding > its limitations is as important as understanding its features. > > My 'scope is an HP, so I'll leave any suggestions about the value of that > particular model to those here who follow the Tek scope line. > > Ron AC7AC > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
In reply to this post by Tom McCulloch
Tom,
If your main interest is just in observing the fundemental wave, I would say that a 100 mHz 'scope would be quite useful up through 30 MHz and with caution even to 50 HHz - and with some more cautions, useful for looking at signals up to 100 MHz. Ron's point is well taken where there is interest in observing for waveform distortion (an indication of parasitics), or for knowing that digital signals are nice and square (that is where the 10:1 rule should definitely be applied). When you push the limits of the vertical amplifiers in a 'scope, even waveforms with lots of harmonic content begin to look like sine waves, and as long as you know that, the 'scope can still be quite useful. There is one other factor that must be considered - and that is the falloff in amplitude response as you approach the upper limit of the 'scope rating. The frequency rating of a 'scope is normally that frequency where the amplitude response is 3 dB down from the response at lower frequencies. So don't expect RF Voltage measurements to be accurate at the upper limit. If you regard the upper limit of the 'scope's calibrated voltage response to be about 1/3 of its frequency rating, all should be good - in other words, a 100 MHz 'scope will provide good voltage measurements up to about 33 MHz. And don't forget that 'scope probes also have frequency ratings to them. Get a set of probes that have a frequency rating equal to or above the 'scope rating - the higher the frequency, the more pricy they become. I like Tek 'scopes, - the Tek 465 and 475 can often be found at $150 to $250. But beware, these and older 'scopes are no longer supported by Tektronics and while repairs by independents are possible, parts availability may be another matter. If you are looking for an investment, go with something more recent, but if you are willing to purchase an older one knowing the drawbacks should something go wrong with it, you can find a good one at a low price. Anywhere between $150 and upward can get a working 'scope, but proper 10:1 probes will likely cost another $100 or more for a pair. Make your choices and like with any test equipment, know your equipment and especially know its limitations so it does not cause you to reach incorrect conclusions. What you see is not always what it really is. 73, Don W3FPR > -----Original Message----- > > I'll follow this thread with interest, as I too am considering a scope > purchase. > > I've heard comments such as Ron's before. I'm wondering if > anyone has any > thoughts on what bandwidth would be appropriate for "casual" use and what > someone might expect to pay for a use one? > > Thanks in advance > Tom > wb2qdg > k2 1103 > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
In reply to this post by Tom McCulloch
I have never even gotten CLOSE to needing the 200 MHz bandwidth of my Tek
465, and it was around $100 on eBay a while back. Be patient, and you'll get something decent. Dan / WG4S / K2 #2456 -----Original Message----- From: [hidden email] [mailto:[hidden email]]On Behalf Of Tom McCulloch Sent: Sunday, June 25, 2006 1:40 PM To: Ron D'Eau Claire; 'Jack Regan'; [hidden email] Subject: Re: [Elecraft] Scopes I'll follow this thread with interest, as I too am considering a scope purchase. I've heard comments such as Ron's before. I'm wondering if anyone has any thoughts on what bandwidth would be appropriate for "casual" use and what someone might expect to pay for a use one? Thanks in advance Tom wb2qdg k2 1103 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
In reply to this post by Tom McCulloch
I'll also follow this thread with interest, as I am also considering a scope
purchase. What about a PC scope like the Bitscope: http://www.bitscope.com? Anybody use one of these? Wayne or Eric, any chance of an Elecraft scope kit? Darrell On June 25, 2006 10:40 am, Tom McCulloch wrote: > I'll follow this thread with interest, as I too am considering a scope > purchase. -- Darrell Bellerive Amateur Radio Stations VA7TO and VE7CLA Grand Forks, British Columbia, Canada _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
In reply to this post by Dan Barker
You all caught me wearing my "engineering" hat, not my technician's hat.
Working in an development lab I often used a scope to study aberrations of a variety of signals, not just to see a nice square wave. As others pointed out, parasitics are often a much higher frequency than the fundamental signal and may not display at all on a low-bandwidth scope. The signal well look perfect even if it doesn't "sound" perfect. Any variation from a perfect sinusoidal signal requires that the amplifier be able to handle harmonics of the base frequency of the waveform. The more harmonics, the more accurate the display. The 10X bandwidth "rule" is strictly a "rule of thumb". In theory you need infinite bandwidth to reproduce a signal perfectly. As always, practice demands something less than theoretical perfection. If all you want to do is see *a* waveform on the display and not necessarily an accurate view of an unknown waveform that is being presented to the input, then by all means you can use a scope up to and even beyond its vertical bandwidth specs. Service technicians usually don't need the wide bandwidth of a lab scope. They commonly use a 'scope for a quick check on the frequency and amplitude of a signal and perhaps looking for any gross distortion that might be present. That's why so-called "Service Monitors" used on many tech benches include a simple 'scope that has a relatively low bandwidth compared to what's found in most engineering labs. Like using any tool, it's important to understand the limitations of the 'scope on your bench as well as its features. And speaking of features, I don't know the particular Tek scope being considered, but dual-trace capability is an invaluable feature to me. I often use the dual-trace capability to study the phase difference of two signals. Buying a 'scope is sort of like buying a personal truck to haul stuff around. We seldom understand the need closely enough to know exactly what we should get. And, no matter how big of a truck we might get, we'll eventually find something too big and heavy to fit in it! Still, that doesn't detract from its usefulness for hauling all the things that do fit. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
In reply to this post by Darrell Bellerive
On 25/06/06, Darrell Bellerive <[hidden email]> wrote:
> I'll also follow this thread with interest, as I am also considering a scope > purchase. > > What about a PC scope like the Bitscope: http://www.bitscope.com? Anybody use > one of these? I have one of those and I haven't been able to see RF signals on it properly; it looks like my signals are drowned in noise. I have the feeling that they are designed for "usual" LF electronics and the circuit is too simple to do the proper signal conditioning. On the other hand, it has open design (like elecraft), so maybe someone can improve them :-) I also have a Velleman PCS500A: http://www.velleman.be/be/en/product/view/?id=345333 The scope itself is good with 50MHz bandwidth, but it comes with the most crappy software I have ever seen, and Velleman refuses to release programming info about the scope. > Wayne or Eric, any chance of an Elecraft scope kit? > That would be great! 73 Alex OZ9AEC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
In reply to this post by Jack Regan
On 25/06/06, Darrell Bellerive <[hidden email]> wrote: > I'll also follow this thread with interest, as I am also considering a > scope purchase. > > What about a PC scope like the Bitscope: http://www.bitscope.com? > Anybody use one of these? I have one of those and I haven't been able to see RF signals on it properly; it looks like my signals are drowned in noise. I have the feeling that they are designed for "usual" LF electronics and the circuit is too simple to do the proper signal conditioning. On the other hand, it has open design (like elecraft), so maybe someone can improve them :-) I also have a Velleman PCS500A: http://www.velleman.be/be/en/product/view/?id=345333 The scope itself is good with 50MHz bandwidth, but it comes with the most crappy software I have ever seen, and Velleman refuses to release programming info about the scope. > Wayne or Eric, any chance of an Elecraft scope kit? > That would be great! 73 Alex OZ9AEC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
In reply to this post by Alexandru Csete
Too bad as it would have been a relatively inexpensive way to get a scope and
spectrum analyzer. On June 25, 2006 12:30 pm, Alexandru Csete wrote: > > What about a PC scope like the Bitscope: http://www.bitscope.com? Anybody > > use one of these? > > I have one of those and I haven't been able to see RF signals on it > properly; it looks like my signals are drowned in noise. I have the > feeling that they are designed for "usual" LF electronics and the > circuit is too simple to do the proper signal conditioning. On the > other hand, it has open design (like elecraft), so maybe someone can > improve them :-) > -- Darrell Bellerive Amateur Radio Stations VA7TO and VE7CLA Grand Forks, British Columbia, Canada _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
A scope can be used with a demodulator, (detector) probe to bring the RF
signal and modulation into the audio range of the scope. Sometimes you do not need perfect triggering on the RF; but it is sufficient to see the amplitude envelope to tell if you have about the right amount of RF voltage for the given application. So don't give up on the PC scope programs until you try it with a detector probe. There are many suitable probe circuits, Goggle for "RF detector probe" and you will find circuits, articles, and maybe a kit. -Stuart K5KVH _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
«
Return to Elecraft
|
1 view|%1 views
| Free forum by Nabble | Edit this page |