Keying CW on the ELECRAFT K3S at 75 wpm and getting FULL QSK HF RECEIVE AUDIO between letters

Here is a video demo'N an experimental setup to key an ELECRAFT K3S at 75 wpm(FULL FAST QSK) so you are able to hear background HF RECEIVE audio between letters 

a test run using a setup using all LINUX FREE SOFTWARE to run REMOTE RIG OPERATIONS for QRQ CW at 75 wpm...trying to achieve good FULL QSK with RECEIVE HF AUDIO between letters at this speed...

is the typical full qsk mode using the CW JACK and qrq+ setting on this Elecraft K3S....there is no RECEIVE HF AUDIO between letters at 75 wpm....however, using this software method to key the rig ...keying the PTT ahead of the arriving CW TONE ...sending CW using A2 MODE ...AFCW... Receive HF AUDIO can now be heard between letters...
NOTE: (the k3s setting for PTT-RLS was set to ZERO in its config menu) using an audio derived PTT KEYING circuit

the PTT tone is sent first by the REMOTE OP's station to give the RIG time to close the PTT jack fully before the actual AFCW TONE arrives (audio OVER ip) then the actual CW AUDIO NOTE to be transmitted is sent...and goes into the RIG's TRANSMIT LINE INPUT jack and then out to RF etc

there are some interesting timing values that have to found are just a few..
- how long it takes the RIG's PTT to close (12 ms on my rig)
- how long over the local area network does it take for the TRANSMIT CW TONE to arrive at the RIG....the TONE has to be delayed 12 ms on this setup example to give the PTT TONE enough time to activate the PTT CIRCUIT and CLOSE IT all the way...getting the RIG ready to transmit any TRANSMIT AUDIO it hears on its LINE IN jack...

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Comment by Chuck aa0hw on December 10, 2018 at 7:08pm

Here is a similar video demo'N keying the K3S at 71 wpm with RX audio between letters -  this time with a direct sound card connection to the audio over ip travelling necessary with this setup:

setup - concept
the K3S won't key at 71 wpm very well by itself in FULL QSK
there are several issues the K3S has when it comes to qrq cw keying
1. in full qsk mode, the K3S will shorten all cw elements
2. in full ask mode the K3S will also have cw element timing jitter which can change and vary at random - any and all cw elements by PLUS or MINUS 3 to 4 milliseconds, which at QRQ SPEEDS can be a significant hindrance to smooth copy and perfect code being transmitted by the K3S on its own....
3. in full qsk mode, the K3S can NOT achieve good QSK RECEIVE audio between letters at 71 wpm

to counter the disadvantages inherit in the K3S DESIGN listed above for QRQ CW OPs....using AFCW mode and some LINUX SOFTWARE APPs, a way to achieve much better performance is tested:

1. PERFECT cw element timing for EVERY cw element ...NO JITTER whatsoever in how long a cw note should be...NO SHORTENING of any CW ELEMENT was heard or seen on the scope

2. good FULL QSK RECEIVE audio was achieved between letters sending CW with a software CW KEYBOARD at 71 wpm....using a text file to send cw...TOM's famous article about copying cw over 70 wpm

3, using AFCW mode, you can choose your own RASIED COSINE WINDOWs, your own RISE/FALL Time, your own CW weight by exact same amount of time, or weight by percentage, you can choose your own dot/dash ratio, your own CW sidetone PITCH frequency just to name a few of the advantages when using the:

AD5DZ software CW Keyboard software APP:

basic concept of the APPs and their use for this purpose...

a LINUX LAPTOP's USB SOUND card is directly hooked up to the K3S's LINE INPUT JACK with an audio cable form the LAPTOP's USB SOUND CARD's left channel LINE OUTPUT to the RIG's line input jack...this is for TRANSMITTING the CW NOTE that the laptop makes with the AD5DZ software CW KEYBOARD ....from the LAPTOP's USB SOUND CARD right channel LINE OUTPUT another audio cable goes to the audio derived PTT CIRCUIT that closes the PTT on the rig

the PTT is keyed allow TRANSMIT AUDIO to be transmitted from the CW audio arriving at the RIG's LINE INPUT jack...
- with a 15 millisecond delay, the CW AUDIO NOTE is presented to the RIG's LINE INPUT jack - for TRANSMISSION on HF using AFCW MODE on LSB(the 15 ms delay is to give the PTT enough time to close from the audio derived PTT keying circuit activation)
the RIG's PTT is closed by an audio derived PTT keying circuit:

how long the PTT remains closed after the CW NOTE is finished is set by the CALF SIDECHAIN GATE app's RELEASE this case it was 17 ms...discovered by trial and error while listening to a text file at the 71 wpm speed and adjusted up and down until best setting is heard for most RX audio between letters...without hearing any audio glitches in the keying

NOTE: no rf was transmitted, RF POWER was at ZERO


green wave is direct note form the cw keyer
RED WAVE is the return audio from the RIG's RX audio and the RIG's INPUT AUDIO TRANSMIT MONITOR


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