Vic is right, scope probes have a peak voltage rating associated with them. Violate those ratings at your own peril.
73, Don W3FPR On 4/8/2011 7:35 PM, Vic K2VCO wrote: > Be careful if it's a K2/100. Probe ratings decrease with frequency, and the > voltage > applied to the usual scope probe with 100w going into a 50-ohm load at 28 mHz > will blow > the 10x attenuator in probe. I don't need to tell you how I know this! > > On 4/8/2011 4:15 PM, Don Wilhelm wrote: >> John, >> >> I have to condition my answer on this one because I do not know what kind of >> 'scope >> you have available. >> >> If it has a sufficiently high frequency response (3 times the frequency of >> the RF to be >> measured), and it has a 10X probe with it, then the procedure is easy - just >> connect >> the 10X probe across your dummy load. If your dummy load does not have easy >> access to >> connect the 'scope probe, use a Tee adapter at the dummy load end to gain >> access to >> the center conductor. >> >> If you do not have a modern 'scope with adequate frequency response, contact >> me >> off-list and I may be able to dredge some old information out to enable you >> to do the >> same thing - it is somewhere in my ole references. >> >> CW: Set the sweep rate to something slow matching your keying rate (key the >> TX with a >> string of dots), and observe the RF waveform. If it has sharp transitions, >> that is an >> indicator of potential keyclicks. Look at the 'scope traces shown in the >> Elecraft K2 >> Keying Waveform Mod instructions for an example of what to look for. >> >> For SSB: Set up about the same as for CW (the sweep rate will be at an audio >> rate). >> You will have to review some of the waveforms in the ARRL Handbook to see >> what clipping >> looks like before being able to judge the waveforms. For amplitude, compare >> the peak >> of the audio wave to what is obtained in CW mode - and that level will >> represent your >> PEP. >> >> Note that you will not actually be able to observe splatter with the 'scope, >> that takes >> a Spectrum Analyzer - if the waveform shows clipping (abrupt transitions at >> the peaks), >> that is an indicator that splatter is occurring, but the 'scope will not >> show it >> directly. >> >> 73, Don W3FPR >> >> On 4/8/2011 3:06 PM, John Cooper wrote: >>> How would I use a scope to monitor key clicks on cw, and the waveform on >>> ssb? Also >>> anything else I can do with a scope too? This is in reference to a K2 IE >>> where do >>> the probes go and so forth. Off list is fine too. Couldn’t find any >>> definitive >>> answer in the archives. >>> >>> >>> WT5Y ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
