[Elecraft] K3 TX delay

[Bill VanAlstyne W5WVO]

Your explanation of the issues surrounding QSK in the K3 is well worth the 
read, Guy, and I thank you for it. I’ll stop quibbling about milliseconds on 
the T-R change-over. :-)

I am not a QRQ operator, far from it; I top out at around 30-35 WPM for 
rag-chew copy in my head. But in regular QSK mode with default settings (8 
ms delay, etc.), I do find it difficult to hear a weak DX station coming 
back between my bauds. Your attribution of this to wetware factors is 
compelling, and I’m sure you’re right, at least in part.

Another factor, however, might be that the pitch of the DX station is 
typically the same as the pitch of my sending sidetone, since I have the DX 
station centered in my passband -- which is usually set pretty tight. (I’m 
not one of those guys who likes to listen to weak, QSB-laden CW in a wide 
passband. It drives me nuts.) I could offset the DX station a few Hz by 
moving the IF shift to one side, which I’ll try.

I also found this paragraph to be especially interesting:

“ ... where the complaint was not hearing between bauds, the situation was 
remedied by changing the front end setting of "PRE" to "ATT" (yes on 160m, 
too), backing off the RF gain until the band noise was a tad less than 
moderate, and setting the AGC to slow.  All of a sudden the QSK "sprang to 
life" ... It appears that QSK does not "sound right" when using fast AGC (my 
own impression as well) ... ”

I totally get it about reducing the front-end gain of the receiver on most 
bands. However, with my current pathetic HF setup using a rather small wire 
antenna (I’m primarily a 6-meter op, which is where the big aluminum is for 
the time being), I’m really not troubled by too-strong signals, and the DX 
stations I hear are typically below my AGC threshold. That may all change in 
the near future, as I’m working on some new antenna ideas for my HF setup. 
But for now, I don’t really see why changing the AGC response speed should 
change anything. Nevertheless, I’ll try it.

I do find, as have others, I guess, that using the QRQ mode at regular CW 
speeds makes detecting when the other station comes back much easier, 
subjectively. I now have a much better understanding of what had to be 
sacrificed to get that super-fast QRQ mode T-R switching, and why these 
trade-offs are unavoidable. For this and a number of other reasons, like 
being able to listen to the "up" DX pile-up in one ear, the KRX3 is going to 
be put higher up on my must-have list.

Bill W5WVO