On 10/20/2018 11:47 AM, Jim Garland wrote:
A well-designed amplifier QSK circuit should never allow hot-switching
of the amplifier's T/R relays under any circumstances. There are
several ways to accomplish this goal, none of them expensive or
complicated.
Yes. Ten Tec implemented this quite effectively in their Titan 425 using
discrete semiconductors in a late '70s design. Their design positively
prevents hot switching -- I know that from experience. Their rigs didn't
include keyers, and TX delay from the rig was implemented by keying the
amp and having the amp key the rig. HOWEVER -- I have successfully had
my rig PTT key the SSB PTT line with no issues for both full QSK and
semi-QSK. I used those amps for more than ten years, and with TS850s,
Omni V, FT1000MPs, K2s, and K3s.
I first ran full QSK, but as a contester, found myself needing to
replace vacuum relays at the most inopportune times. And, as I worked at
higher speeds (30 WPM or so), got reports that dits were getting
shortened. For both reasons, I went to semi-QSK. And eventually replaced
those amps with 87As.
73, Jim K9YC
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