Re: using a scope on a k2
Posted by
Don Wilhelm-4 on
Apr 08, 2011; 11:48pm
URL: http://elecraft.85.s1.nabble.com/using-a-scope-on-a-k2-tp6254907p6255691.html
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
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