Re: using a scope on a k2
Posted by
Vic K2VCO on
Apr 08, 2011; 11:35pm
URL: http://elecraft.85.s1.nabble.com/using-a-scope-on-a-k2-tp6254907p6255668.html
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
--
Vic, K2VCO
Fresno CA
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