QRQ CW TX/|\RX high Q resonant VLF FERRiTE ROD antennas - how to combat ringing & element elongation

[Chuck aa0hw]

working with 4Khz VLF ferrite rod TRANSMIT and RECEIVE antennas that are High Q & tuned to resonance(see previous 2 videos for the more info on the FERRITE ROD HIGH Q antennas being used for TX & RX on 4Khz VLF):

https://youtu.be/LQ82YZHwFvA

https://youtu.be/N6ETTy1Sf6g

to combat RINGING and CW ELEMENT ELONGATION, the CW ELEMENTs are 1st CHOPPED by 23 milliseconds by the CW KEYBOARD VLF TRANSMITTER app, and then after RX by a soundcard SDR, the elements are sent to a CW REGEN software setup that adds back the 23 milliseconds (for more info on CW REGEN software setup operations...see this playlist: http://www.youtube.com/playlist?list=PLfFan4sDonOdFGeEDASG8tcadafHQ...

soundcard SDR SOFTWARE, CW KEYER and CW KEYBOARD and SDR MODULES are all from RECRI KEYER: https://github.com/recri/keyer

CW REGENERATION by REAGATE and RECRI KEYER's CW KEYER app:

REAPER's REAGATE VST plugin, measures the threshold signal strength on the rise & fall time of each CW ELEMENT, then produces a CW MIDI NOTE output based on that measurement...by adjusting the options on both the CW KEYBOARD's compensation and the REAGATE's 'HOLD' option, proper CW TIMING is restored for the CW speed being used...the REAGATE midi note output 'keys' the RECRI KEYER's CPO app that has an adjustable pitch, rise/fall times etc...

[Chuck aa0hw]

VLF CW soundcard SDR Transmitter & Receiver: TX uses square Wave PulseGen APP; RX uses CW Regen APP

LIVE DEMO of a 4kHZ VLF CW Transmitter & Receiver by soundcard SDR; both TX/RX using high Q, tuned Ferrite Rod antennas. Transmitter is by a square wave pulse generator, ( simple C code chatGPT written app here): https://u.pcloud.link/publink/show?code=XZOfdy0Zxfw3pVL0n0VgxSKge7X...

that gets key'D by a CW KEYBOARD's output by going through a sidechain gate method...

see this playlist for more info on CW REGEN/REkeying https://www.youtube.com/playlist?list=PLfFan4sDonOdFGeEDASG8tcadafH...

The Square wave is set to a 90 uS(microseconds) pulse width & using only its positive pulses(which helps to save battery power for portable operations) it goes out the sound card and into the high Q input winding(@4 turns) of a large Ferrite Pulse Transformer Transmit Antenna, that is parallel resonant at the same 4Khz freq. by placing a .1 uF HV CAP across its output windings(@400 turns) DUE to the high Q resonance nature of the TRANSMIT ANTENNA, the SQUARE WAVE PULSES are induced to merge into a full CW NOTE with a 10ms rise and fall time(with r/c like exponential waveshapes on edges) This is a bit too soft for copy at QRQ, so another APP is used to REGENERATE the incoming cw tones into a cloned, new, adjustable CW note by the RECRI KEYER's CW CPO module https://github.com/recri/keyer

The Receive Antenna is a modification of the patented TWIN COIL FERRITE ANTENNA https://patents.google.com/patent/US6529169B2/en

video demo: https://youtu.be/N6ETTy1Sf6g