[Amps] QSK on the cheap AND Parasitic

[Paul Christensen]

> The only way to know is measure it.

And timing measurements are easy with an oscilloscope, triggered by the key 
line.  As you point out, some transceivers add delay through a menu 
parameter to ensure that the RF envelope does not appear before the amp has 
a chance to fully switch into Tx.  But notice that the manufacturers have 
difficulty adding back in the time period of the delay.  This results in 
shortened keyed elements.  The keyed envelope should be stretched by an 
identical amount of delay time.

I recently went through this exercise while programming a QSK switch 
designed to switch classic Rx/Tx separates.  The idea is to use an outboard 
PIN diode switch to perform the switching function, but timing is precisely 
controlled by an Arduino Nano microcontroller programmed in C++.

The device operates from any straight key, electronic keyer, or 
semi-automatic bug.   But most importantly, lead-in and tail times can be 
independently adjusted in 1ms increments through software to best match the 
keying characteristics of the Tx.  The keyed envelope is stretched by the 
exact amount of lead-in delay time.  The program works well and does not 
suffer from the same keyed element shortening that today's manufacturers 
cannot seem to control.

Paul, W9AC