Transmit QRQ CW on your RIG in AFCW MODE - some advantages and tips on getting it to work well for qrq sending

click on the YOUTUBE icon at the bottom of any video in this 6 part series that you are interested in to see its discussion notes and links

One of the advantages of sending CW this way, is that you can send a very customized and optimized cw waveshape that has extremely low distortion and harmonic energy... extremely low key clicks, and a very pleasant sound for the CW NOTE as compared to many rigs where you can not adjust the rise/fall time or the type of it R/C exponential, or raised cosine...  

NOTE:  at qrq cw speeds above 70 wpm, and especially over 100,  the edge noise generated by even the best raised cosine waveshape with 8 ms rise/fall time...will still create lots of edge - from the percussive effect of the qrq impacts on the start of each element...HOWEVER,  passing the 8 ms raised cosine waveform through a CW AUDIO bandpass filter FIRST, before going to the RIG for transmit, will lower that edge noise to almost the combination of the ideal waveshape, RISE/FALL TIME,  and an appropriate final audio bandpass filter, will create a CW NOTE that is far beyond what can be achieved by most of the commercial RIGs used for transmitting CW...when you transmit CW using AFCW MODE(a2 mode) if every precaution and tip that is described in the 6 videos above is followed...

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Comment by Chuck aa0hw on October 19, 2020 at 12:36pm

here is another video example of AFCW mode using a REMOTE RIG SETUP with a Raspberry PI 4

follow up video from the first one in this series: this is a REMOTE RIG transmit AFCW MODE test to a RASPBERRY PI 4 remote rig interface...the RIG has its own sound card, which the PI 4 is using as its sound card...the purpose of this test is to see how well the AD5DZ, RECRI KEYER, two tandem bandpass filter modules work at virtually eliminating all unwanted harmonics below and above the CW TONE that is being transmitted - 680 hertz - and to see that the RAISED COSINE wave shape of the CW NOTE, maintains its integrity and is not distorted by the bandpass filter setup. The CW AUDIO you are hearing on this video is from the TRANSMIT AUDIO MONITOR that is on the PI itself and sends what it is going to TRANSMIT to the RIG's LINE INPUT, back to this recording remote rig operations laptop so that it can be analyzed for spectrum purity, bandwidth and waveshape before actually going out on the air with it... the 2 staggered bandpass filters are a refinement of the previous AFCW TRANSMIT CW mode videos - see these 2 playlists for more info:

NOTE: that the @20 ms CW NOTE delay provided by the 2 staggered bandpass filters at their settings shown, provided the ideal amount of CW NOTE delay to the RIG's line input, to allow the first tone, a 5555 hz tone, that is used to only activate the rig's VOX VOICE PTT circuit to turn on and get ready to TRANSMIT any "other" audio at its LINE INPUT jack...fully, before the FILTERED CW TONE arrives for transmit at the RIG's line input so that NONE of the first sections of the CW NOTE gets choppped off by the RIG's PTT VOICE VOX circuit...which would chop the first bits of the CW NOTE if the CW NOTE itself were used to trigger ON, the voice vox PTT circuit ...etc... having just the right amount of CW DELAY, just enough to get the PTT to turn on fully before the CW NOTE gets there...allows for the MOST QSK RX AUDIO to be heard at the remote OP's PC/location

Comment by Chuck aa0hw on October 20, 2020 at 10:37am

Here is a SPECTRUM ANALYSIS of the 680 hz CW TONE and the 5555 hz PTT TONE down to minus 185 db when using the AD5DZ RECRI KEYER FILTER MODULES for REMOTE RIG OPERATIONS with the RIG::PI 4  

NOTE: that even all the way down to -185 db, the PTT tone harmonics do not creep below the 4khz limit which is the brick wall low pass filter edge of the ELECRAFT K3S transmit nothing of the 5555 PTT tone gets transmitted by the K3S...(all of the 5555 hz audio energy is ABOVE the 4Khz mark)

                                                                 -185 db

Comment by Chuck aa0hw on October 20, 2020 at 10:45am

Here is a picture of the PI 4 - REMOTE RIG operations interface software setup (click on pic for full screen view)

Comment by Chuck aa0hw on October 20, 2020 at 12:03pm

TRANSMITTING QRQ CW in AFCW mode - 2 CW Bandpass filters in tandem LIVE test run to adjust CW sound

brief demo follow up from this video -

this is a test run to show the TANDEM CW filter settings and adjust some of the QRQ CW KEYBOARD settings to modify how the QRQ CW will sound as it gets TRANSMITTED in afcw mode by the RIG

Recri Keyer


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