[Elecraft] Default K3 transmit delay may be too short for slow QRO amplifiers

[Bob Wilson, N6TV]

On Fri, Jun 8, 2018 at 12:37 PM, Igor Sokolov <ua9cdc at gmail.com> wrote:

> My setup is optimized for traveling/field operation. I do not need
> additional boxes in the form of Winkey or external QSK.


Very good.  I assume you are using CONFIG:PTT-KEY set to RTS-DTR to have
T4RW provide CW and PTT over the K3 USB cable (or serial cable).


> I use external keying from computer through USB-COM adapter.


OK.  For the K3S, or K3 with KIO3B upgrade, no adapter is required (it is
built in to the K3).


> The logger that does CW keying is TR4W. No keying compensation helps to
> achieve correct CW weight if TX Delay in K3 is set to say 20ms and CW speed
> used is above 30WPM.


The TR4W manual <http://tr4w.net/TR4W_Reference_Manual_4.01.pdf> says:

"7.Support for PTT with programmable delay to ensure that antenna relays
are cold-switched."

But I could not find any further documentation showing how to set the CW
PTT delay to 20 ms in TR4W.  If the PTT line is held closed by the
software, no keying compensation is required, and CW output will be fine.
But, if you're trying to do QSK (full break-in) with VOX and external
keying from TR4W, with no PTT output, you will either have to use a
different radio, or use different software like Win-Test that (in
v4.28.0-dev) supports keying compensation, or an external keyer with PTT or
keying compensation, like a WinKey.

Perhaps you can convince the author of TR4W to add keying compensation (
*not* weight), a setting that lengthens every dot or dash by a fixed amount.


> Dependency of CW weight from TX Delay is only inherent in K3. All other
> rigs do not have this dependency.
>

Most rigs will shorten the first dot or dash (semi break-in) or every dot
or dash (QSK full break-in) by a few ms to compensate for the TX delay
setting, the delay between the amp RELAY closure, and the RF output.  Some
rigs may use a hardware "buffer" for external keying, to provide perfect
timing even with a  PTT delay, but I don't know which ones do this (Icom
perhaps).

Again, for hand sending with the internal keyer of the K3, all TX DLY
values work fine, no shortening of RF output.

73,
Bob, N6TV