Oscilloscope
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I recently wrote an email to Elecraft re my K-1 transmitting with very weak
power on twenty meters. I got a quick and informative reply back from Gary suggesting that I use a "scope" to measure the peak-to-peak voltage on various pins. Thinking this might provide me with a great learning experience, I borrowed an oscilloscope from a friend of mine, together with three books. I have discovered that it is easier to fly airplanes on instruments in thunderstorms at night than it is to figure out how to measure voltages using an oscilloscope. Any advice anyone has would be appreciated...thanks and 72, Ci Ci Jones WU7R FISTS 10789 NAQCC 306 _______________________________________________ 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 |
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Ci, WU7R wrote:
I recently wrote an email to Elecraft re my K-1 transmitting with very weak power on twenty meters. I got a quick and informative reply back from Gary suggesting that I use a "scope" to measure the peak-to-peak voltage on various pins. Thinking this might provide me with a great learning experience, I borrowed an oscilloscope from a friend of mine, together with three books. I have discovered that it is easier to fly airplanes on instruments in thunderstorms at night than it is to figure out how to measure voltages using an oscilloscope. Any advice anyone has would be appreciated... ------------------------------------------------ Some oscilloscopes are that way, especially the newer ones! They have more bells and whistles than anyone is likely to ever need. And like most things overloaded with bells and whistles, they're incredibly complicated to operate. I suggest you contact the friend and explain what it is that Gary is asking you to measure, and getting his instructions on how to set the controls. The trickiest part is usually the time base - the part that makes the spot move from left to right across the screen (and, if it's moving fast enough, make the spot look like a horizontal line). There are usually a lot of controls that affect when the spot starts each sweep as well has how fast it goes. If you have a sweep in the tube, it's usually placed on a center line of the grid on the face by adjusting a knob. Then voltages applied to the "vertical" inputs make the sweep move up or down (or both). The distance the trace moves up or down is an indication of the peak voltage. An oscilloscope is probably the single most useful measuring instrument one can have on the bench. Because it can do so much it can be a monster to learn. I have an old "analog" 100 MHz HP 1740 scope on my bench simply because it lacks many of the little "features" of newer digital scopes and so is that much easier to operate! Still, at times I have to stop and think about which of the dozens of buttons I need to push to do what I want... 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 |
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In reply to this post by Ci Jones
That's cheating! (They light up at night). Try some embedded Tx in the
daytime! Oops, wrong thread. You want to pick a range that nearly fills the screen. The 10x position on your probe will load the test circuit less, so use it if you can. After getting the trigger to work right (or just try Auto or let it run free), adjust the vertical gain to almost fill the screen. Use the vertical position to align the bottom of the trace with a line on the reticle, and count the divisions to the top of the trace. Centering the display seems more normal, but then the accuracy is lessened (in my opinion) by nearly half. You can always center it and read off half the peak-to-peak divisions. Multiply divisions by the Vertical Amp setting (and by 10 if using the 10x probe setting) and there you are. You might give us some more info on what is specifically bugging you. Trigger? Display size? Be sure the cal function shows nice clean square waves. There's usually a compensating cap on the probe that can really skew the look of the calibration signal. Adjust it for nice square traces. I guess I could set up some tests and photograph my scope and settings for you. Name a test point, expected voltage, and I can try to demonstrate what I'd do. Make it something generic tho, I've only a K2 (like base of a driver or some data line of a uProcessor. If you ask nice, maybe some 'scope-enabled K1 owner will help! Dan / WG4S / K2 #2456 / Tek 465 PS: If you think an ILS is hard, try pushing a Mooney into a tight hangar with one of those battery powered nosewheel pusher thingies. <snip> it is easier to fly airplanes on instruments in thunderstorms at night than it is to figure out how to measure voltages using an oscilloscope. </snip> _______________________________________________ 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 |
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In reply to this post by Ci Jones
Ci:
I have done both in my life time and I'll take the O'scope problem any day...LOL You need to set the scope in the auto trigger mode and adjust the sweep speed to a speed that will show you pretty much a solid wide band across the screen when connected to the test point. You need to adjust the input attenuator to the expected voltage range and then measure the nimber of divisions the wide bad covers on the screen. It is easy to do if you set the bottom of the band to a large line and then read how many large boxes it covers and what part of another. Then take that number and multiply it times the volt/div setting on the input attenuator scale. You can reduce the attenuator to produce the largest display without filling the screen completely...The result will be the Peak to Peak voltage of the signal at that point. It really helps if you have another unit that is working that you can compare signals with. One other note some probes are attenuated by 10 times if this is the case you need to multiply the first product by 10... At least while using the ocsope the windshield is not covered with St. Elmo's Fire....LOL 73 Jim K4ZM _______________________________________________ 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 |
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In reply to this post by Ci Jones
In a message dated 7/21/2005 19:52:11 GMT Standard Time, [hidden email] writes: Some oscilloscopes are that way, especially the newer ones! Thanks again to all who responded. I have printed your advice and I think I have used the scope successfully to locate the culprit--a bad cap. Again, thanks...Ci Ci Jones WU7R FISTS 10789 NAQCC 306 _______________________________________________ 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 |
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All the suggestions in this thread are good.
However, if you are looking for an excellent tutorial on the use of O'scopes here are links to Paul Harden, NA5N's, 2 part tutorial "The Handyman's Guide to Ocilloscopes" in .pdf version. http://www.aoc.nrao.edu/~pharden/hobby/Scope1.pdf http://www.aoc.nrao.edu/~pharden/hobby/Scope2.pdf I keep a copy handy at my bench! Don, K5DW _______________________________________________ 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 |
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Great info! Thanks!
At least there is something other than "License Exams" on here!!! What do licence exams have to do with Elecraft anyway?? 73 Jim W7RY At 09:40 AM 7/22/2005, Don Wines wrote: >All the suggestions in this thread are good. > >However, if you are looking for an excellent tutorial on the use of >O'scopes here are links to Paul Harden, NA5N's, 2 part tutorial "The >Handyman's Guide to Ocilloscopes" in .pdf version. > >http://www.aoc.nrao.edu/~pharden/hobby/Scope1.pdf > >http://www.aoc.nrao.edu/~pharden/hobby/Scope2.pdf > >I keep a copy handy at my bench! > >Don, >K5DW > >_______________________________________________ >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 |
Re: Oscilloscope NO MORE LICENCE EXAMS! (please)?
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Jim W7RY wrote:
> Great info! Thanks! > > At least there is something other than "License Exams" on here!!! > > What do licence exams have to do with Elecraft anyway?? > > 73 > Jim W7RY > Well, you see, Jim, it's like this: Elecraft is a ham radio vendor and a great one at that; most of the people on this list are hams, too, and, well, they're affected by a common event -- the taking and passing (or failing) license exam. Elecraft = hams = license exams. Simple, really...(!) :) I mean, when you think about it, what do *oscilloscopes* have to do with Elecraft? :-o 73, Joe, W2BRA _______________________________________________ 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 |
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