Posted by
Bill VanAlstyne W5WVO on
Mar 26, 2010; 5:22am
URL: http://elecraft.85.s1.nabble.com/QSK-CW-TX-DLY-vs-CW-WGHT-with-internal-keyer-tp4802215.html
Just thinking out loud here, having recently upgraded my 3-500Z amplifier with fast vacuum T-R relays...
The default (and fastest) QSK transmit delay setting (TX DLY) is 8 ms. At 20 WPM, this shortens the length of a nominal 60 ms dit element to 52 ms long. To regain this lost "dit time" when using QSK, the default setting for the CW WGHT element-to-space ratio is 1.15. (52 ms X 1.15 = 60 ms approximately.) So the 1.15 default weight factor was seemingly arrived at by using 20 WPM as a nominal QSK code speed.
Assuming this reasoning is correct (Wayne/Eric, please enlighten me if it isn't), two things come to mind:
First, since amplifier T-R speeds below 4 ms are readily achievable using vacuum RF relays, and faster than that using PIN diodes, it might make sense to make TX DLY settings of less than 8 ms available -- say, down to 2 ms, while still leaving the default at 8 ms.
Second, as QSK code speed is increased, the TX DLY factor (whatever it is, currently 8 ms by default) becomes a larger and larger proportion of the element time, requiring a larger weight ratio to correct for the TX DLY shortening. For example, at 25 WPM (48 ms element) and TX DLY = 8 ms, a CW WGHT setting of 1.20 would be correct; at 30 WPM (40 ms element), again with TX DLY = 8 ms, a CW WGHT setting of 1.25 would be correct; and so on. Might it make sense to optionally have CW WGHT track with the user's code speed setting during QSK operation? (You wouldn't want to do this in non-QSK CW mode, of course.) The tracking formula would be based on the user's TX DLY setting, whether 8 ms or something faster/slower.
Of course, this would only apply if the internal CW keyer were being used; if using an external key or keyer, you'd be stuck with a fixed CW WGHT setting...
Comments?
Bill W5WVO
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