Posted by
Bob Wilson, N6TV on
Jun 08, 2018; 6:12pm
URL: http://elecraft.85.s1.nabble.com/Default-K3-transmit-delay-may-be-too-short-for-slow-QRO-amplifiers-tp7641779p7641806.html
On Fri, Jun 8, 2018 at 3:22 AM, Igor Sokolov <
[hidden email]> wrote:
> Wayne it is a pity that TX delay setting affects CW timing. Changing TX
> delay from default even one or two steps makes CW much worth. Can you
> figure out a way to make CW timing independent from TX delay? With 5 ms TX
> delay working in many contests I already had to change a pair of relays in
> the amplifier. 10-12 ms would be fine for me. 20 ms will probably suit the
> majority of users. But 5 ms is way too fast and unfortunately cannot be
> altered without spoiling CW sending. I know that I could build external
> sequencer but this does not look neat enough especially for portable field
> operation. Every other radio I had allowed TX delay adjustment to at least
> 20 ms.
Instead of weighting, as Wayne suggested, set "Keying Compensation" or "1st
dit extension" to match the actual TX DLY. This will restore proper CW
timing ratios in the transmitted RF, as you increase TX DLY, since every
dot or dash (or the first one in a message) will be lengthened by a fixed
number of ms.
No footswitch is required, since external keying methods can generate a
leading PTT delay.
If you are using the internal keyer of the K3 for hand sending,
compensation is automatic. No need for any adjustment; use any TX DLY
value you need, and the transmitted dot/dash ratios will still be perfect
(I've measured it on a scope).
If using external keying with a WinKey, use the menu setting for "Keying
Compensation" (QSK), or "1st dit extension" (Semi-Breakin). to apply
matching keying compensation. Example:
CONFIG: TX DLY 010
Actual measured TX Delay 7-8 ms (with jitter)
Set External Keying Compensation (for QSK) to: 7 ms
Set 1st Dit Extension (semi-breakin) to: 7 ms
If using a microHAM Device with a built-in WinKey, the menu settings for
these values were (unfortunately) moved from the WinKey tab of the Router
software. Instead, they are now a single setting under the PTT tab, called
"R/T Delay" (improperly documented). So, in the microHAM Router, PTT tab:
Set R/T Delay to 7 ms
If using a LogiKey K1 or similar:
Set the "K Factor" (keying compensatin) to 7
If using Win-Test with CONFIG:PTT-KEY OFF-DTR for QSK keying over the
serial port DTR pin, or an external keying circuit, set the Keying
Compensation in the Interface Configuration menu to 7 ms (this a new
feature in Win-Test 4.28.0-dev). If using semi-breakin, set CONFIG:PTT-KEY
to RTS-DTR and tell Win-Test to use a PTT Lead time of 10-20 ms, 0 ms
keying compensation.
Most WinKey/N1MM users can simply rely on setting the WinKey PTT Lead time
to a sufficient value. Unfortunately, the WinKey PTT lead times are set in
increments of 10 ms (0, 10, 20, 30 ms), despite the menu settings. If you
ask for 11 ms of PTT delay in a WinKey, you actually get 20 ms of PTT delay.
Note that the K3 will safely ignore any PTT lead time less than TX DLY, so
if you set PTT LEAD to 3 ms you will actually get 7 ms and all elements
(QSK) or the first element (semi break-in) will be shortened by 7 ms.
FYI, the OM Power OM2000A+ non-QSK amplifier manual recommends a TX DLY of
20 ms (!).
Final note: if using CW QRQ mode, the K3 ignores TX DLY completely, and
you get 4-5 ms of TX DELAY (fixed, with jitter). Set keying compensation
to 4 ms.
73,
Bob, N6TV
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