I also commented on the K1EL keyers as he has included Lead-In and Tail Timing all within his keyer eliminating the need to adjust any radio settings which is a consideration when using someone else's radio such as at Field Day, Where using your own Key and External Keyer noes not alter any of the Host Transceiver physical settings (courtesy) Most people are unaware that modern transceivers even have the need for lead-in timing or Tail-Timing these things are all built in but dig into the menus and you will find these settings can be adjusted to suit your operation.
Those of us who grew up with Tube Transmitters and Tube receivers this was common place to avoid the dreaded Chirp and protecting or delicate receivers.