[Elecraft] P3 TX Mon Usefulness?

[Don Wilhelm]

Jim and all,

I agree, the *best* way to look at keying is in the frequency domain, 
but for those who do not have that capability, the time domain keying 
waveshape can be beneficial.

The P3 TX MON option does not show the frequency domain, but it can 
display the rise time and fall time of the CW keying envelope. Those 
rise times and fall times (as well as the shape of the rise and fall 
slope) are a good key to the cleanliness of the keying - the P3 TX MON 
does provide that capability.  Whether the viewer can interpret that 
information clearly and correctly to determine good/bad keying is 
another question.  There is information available on the web showing 
good and bad keying waveshapes.  The figures in the Elecraft K2 Keying 
Waveshape Mod instructions is one such document.

An additional monitor receiver with an IF tap and equipped with a P3 
would be necessary to view the frequency domain of the CW signal.
Quite possible for those who have 2 K3s (or K3S) and at least one 
equipped with a P3, but that is not the "average ham".

While the P3 does show the received signal in the frequency domain, that 
is developed from the IF frequency of the receiver.  The TX monitor sits 
on the transmission line and must respond to the entire range of ham 
band frequencies.  To expect the TX Mon option to convert any transmit 
frequency to a frequency domain display is just not reasonable given 
today's technology.

73,
Don W3FPR

On 8/12/2015 6:20 PM, Jim Brown wrote:
>
> Besides, the time domain (rise/fall times) is the wrong way to look at 
> keying. The only effective way is in the frequency domain, where the 
> P3 with SVGA can resolve to a few Hz when set for narrow scan widths.