[Amps] Be advised: K3 TX DLY differs from documentation

[Jim Brown]

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