[Elecraft] K1 carrier rise/fall times unequal?

[David Steere]

K1 users -

While researching the basic accuracy of my new K1's accuracy display, I 
discovered with an oscilloscope that my unit transmits with about a 5 ms 
carrier rise time, but with a carrier fall time of only about 1 ms.  Having 
learned that the bandwidth of the transmitted signal is a function of the 
keyed carrier's rise and fall times, I'm wondering now whether a 1 ms fall 
time is normal.  According to Figure 12.21 of the ARRL Handbook (2003) in 
the chapter on modulation sources, a 5 ms rise time signal will have a 150 
Hz bandwith, but a 1 ms fall time corresponds to a rather large 700 Hz 
bandwith.  This signal bandwidth, plus the basic accuracy of the K1's 
displayed frequency, affect just how close to a band's edges I would want to 
set my frequency when transmitting.

Can any other K1 owners comment on the rise/fall times of their own units, 
and whether mine might be abnormal?  I think the 5 ms rise time is common 
among modern radios, but that short fall time and the resulting wider signal 
bandwith concern me a bit.  I can, of course, just safely move perhaps 1 KHz 
inside the edge of any band I'm using, but just as a learning exercise, I'm 
curious about this rise/fall time inequality.

Thanks.




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