Re: Default K3 transmit delay may be too short for slow QRO amplifiers

Posted by Vic Rosenthal on Jun 09, 2018; 4:05am
URL: http://elecraft.85.s1.nabble.com/Default-K3-transmit-delay-may-be-too-short-for-slow-QRO-amplifiers-tp7641779p7641828.html

My amplifier uses a reed relay and a vacuum relay for QSK. It uses the
so-called "AG6K circuit" <http://www.somis.org/QSK922.html> which
supposedly makes the usual Jennings RJ1A relay operate in 2-3 ms. I
never had any problems with the default delay of the K3, both before and
after installing the new synthesizers.

I do recall that with the old synthesizers and an external keyer,
increasing the delay above the default even a little seriously messed up
the CW timing. However now I have the new synths. So on reading Wayne's
announcement I decided to so some testing.

I don't notice ANY difference in CW timing, either with the internal
keyer or with an N1MM-operated Winkey, with QRQ mode on or off, with TX
Delay set from 8 to 20 ms., in semi or full QSK mode, up to 40 wpm.

I listened to both the sidetone and the transmitted signal. I didn't
measure anything with the scope, but I have always been sensitive to CW
timing, and it sounded the same to me.

So the upshot is that if you have a slow amplifier, you should be able
to just increase the TX DELAY as needed. And if Bob is right, turn off
QRQ mode too.

But it would be prudent to check the timing with your particular
amplifier with a scope before taking my advice!


73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
On 8 Jun 2018 21:12, Bob Wilson, N6TV wrote:
<snip>

> 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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