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
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