[Elecraft] K3 TX delay

[Igor Sokolov]

> But I am finishing my 300w HF amplifier kit and will be using a dc
> open-frame relay for TR switching of RF.  I guess I can time it using
> my dual trace scope and set K3 TX DLY accordingly (amp will be keyed
> with KEYOUT).  I do not use CW very much on HF so QSK with 300w is
> not necessary (or probably possible).

Even if you use PTT CW and set TX delay for 20 ms you will get choppy CW

> There is one thing I do not see being addressed in this
> discussion.  Maybe more important than clipping of CW characters is
> avoiding QRO "Hot Switching" of RF.  Calculate the RF voltage for
> several thousand ohms impedance (open circuit) that will result if
> the amp is pumping out "globs" of RF before being connected to a good
> load.  The relay contacts will definitely get burned big time.  And
> maybe your output devices will have a short live-span.
>
>
> 73, Ed - KL7UW, WD2XSH/45

The entire topic stems from the fact that I wanted to avoid hot switching of 
the external relays (linear amp, stack switching etc). To acheave that I 
have tried to increase TX delay and got choppy CW. So without external 
sequencer there is a choise between the two - 'hot switching' or 'choppy 
cw'.

73. Igor UA9CDC


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