[Elecraft] K3 TX delay

[Don Wilhelm]

I fail to understand why anyone who is using PTT switching would want to 
set the TX DLY parameter to  greater than the default of 8 ms.  Use PTT 
and a footswitch if you are using a slow amp relay.

If your amplifier uses a slow relay, then you really cannot use QSK, so 
just use PTT and a footpedal instead - things will work out much 
better.  There are QSK mods available for amplifiers that use slow 
relays.  Some mods are relatively inexpensive (the owner does the work), 
while other can cost upwards of $400 (purchase a commercial version).

73,
Don W3FPR

On 2/16/2012 11:05 PM, Igor Sokolov wrote:
>> 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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