[Elecraft] Key Clicks

[Bob McGraw K4TAX]

There are actually 2 time elements involved.  First is the time between 
key closure and the amp key command.  This is approximately 3ms of 
processing time inside the radio.  The second is amp key command to RF 
generation out of the radio.  This is the 5ms between amp key command 
and RF generation.    These are summed together to get the total time 
from Key closure to  RF generation of about 8ms.

One other company to which I'm very familiar,  specs their radio as 15 
ms RF delay.  What is not disclosed is a breakdown of this 15ms,  that 7 
ms of the total time occurs from key closure to amp key command, thus 
leaving 8ms from amp key command to RF generation.  This requires the 
amp to switch in 7ms or less.   A mechanical relay is really being 
pushed to accomplish this fact. This 15ms delay is not user adjustable.  
And the CW rise and fall time is 5ms.  A bit fast for a really clean 
signal.    Another model of the brand offers and adjustable CW rise and 
fall time adjustable between 3 - 10 ms.  The longer time makes for a 
much cleaner CW signal.  Again the delay from key closure to RF 
generation is in the order of 15ms.

Older amp designs, typically those that do not clearly provide QSK 
identification or mode, are typically not suitable for QSK operation.   
Thus switching one of these amps at the faster speeds will most likely 
cause hot switching, resulting in key clicks and eventually relay failure.

I've found the K3S and KPA500 to produce some of the cleanest CW signals 
on the bands.   Timing is the secret and the design team at Elecraft 
have focused heavily on this aspect of these products.

73

Bob, K4TAX


On 6/6/2020 10:19 PM, Victor Rosenthal 4X6GP wrote:
> In fact, it's closer to 5-6 ms when set to 8. And of course it depends 
> on the amp. A general rule to "set it to 9" is silly. It just has to 
> give the relays time to settle down.
>
>
> 73,
> Victor, 4X6GP
> Rehovot, Israel
> Formerly K2VCO
> CWops no. 5
> http://www.qsl.net/k2vco/
> On 07-Jun-2020 04:00, David Gilbert wrote:
>> QSK has everything to do with it.  If you hot switch the amp you create
>> sharp waveforms every element even if the K3 keying is soft. The
>> discussion on the contesting forum included comments that the default
>> setting for TXDELAY on the K3 (apparently 008) isn't long enough and 
>> that
>> it should be set to 009.  Not sure which amps were being considered.
>>
>> 73,
>> Dave   AB7E
>>