Here is a video demo of testing these kind of circuits to key CW on a RIG to find the "best" audio pitch & volume
AUDIO DERIVED CW KEYING CIRCUIT - (what audio frequency to use)
Finding the "best" audio pitch to generate the most voltage from this passive circuit - sent to this circuit from a software CW Keyer's audio PC sound card output
2k load on the TRANSISTOR that grounds the RIG's CW JACK...
when it is turned 'on' by the audio at the circuits input stage.
AUDIO DERIVED CW KEYING CIRCUIT
finding the "best" amount of volume ...
too much = ~ heavier keying
too little = ~ lighter keying
the green wave is the cw keyboards output wave, the RED WAVE is what is being transmitted by the rig from being keyed by the audio derived cw keying circuit shown in the webcam view above on the breadboard...there is an 8ohm to 200 @ ohm isolation transformer at the input yellow with the green clip leads etc... the AD5DZ CW KEYBOARD also has an adjustment for compensation you can increase or decrease the length of the cw elements so between the two settings of volume and compensation...you can dial in how heavy or light you want the rig to sound
Here is a LIVE DEMO of using the full wave doubler circuit with a MOUSER 8 ohm to 200 ohm input transformer - this is a REMOTE CW setup, where a Low Power AM transmitter(1630 Khz) is modulated at the remote OP's desktop by the audio output of a CW KEYBOARD, and an AM RADIO RECEIVER's audio output headphone jack by the RIG is used to FEED the AUDIO DERIVED CW keying circuit input, keyed at 50 wpm
using a low power AM transmitter circuit to modulate with CW AUDIO from a CW KEYBOARD...transmitting at 1630 Khz, to a "rig side" AM RADIO Receiver(GE SUPERRADIO II)...where the AM RADIO's audio output is connected to an AUDIO DERIVED CW Keying Circuit's input
- this video demo's remotely keying CW on an Elecraft K3S at 50 wpm
Here is another interesting low cost circuit that might work well for an audio derived CW RIG Keying circuit:
take a look here too...i think the FETs used in this article are no longer being made... however, there may be some help here -