Fw: [Elecraft] Interfacing K3 to TenTec QSK

[Vic K2VCO]

Richard Ferch wrote:
> I used exactly that setup with my K3 and a Titan (425) during a guest
> operation as VE2OJ in the CW Sweepstakes (Winkeyer to key in on the Titan,
> key out from the Titan to the K3). After the contest I had one report from a
> local amateur of "choppy" CW, which I interpreted as possibly an indication
> of some shortening of the CW elements. It didn't seem to be bad enough to
> hinder copy, as I did not have an unexpected rate of repeat requests, and
> there were no comments on the keying during the contest.
> 
> If I were using that amplifier again in QSK mode I would try to set aside
> some extra time before the contest to look at the CW on a scope to see
> whether any keying compensation was called for.

In my opinion, the shortening was caused by feeding the key line through 
the Titan. But you don't need to do this. The Titan has a fast enough 
t/r switching time and the K3 a long enough delay between key-down and 
RF output to allow you to connect the K3 key-out directly to the Titan 
key-in line.

At the very worst, you might have to increase the K3's TX DLY time a bit 
from minimum -- but I don't think so (the Titan uses vacuum relays 
spec'd at 6-8 ms. pull-in time and the minimum delay of the K3 is 8 ms).

I am using the K3 with a similar vacuum relay in my amplifier and there 
is no hot-switching detectable with the K3 set to minimum delay.

The key-in/out loop protects the amplifier relay against hot-switching 
if the exciter does not provide a built-in delay. Both the K2 and the K3 
do have such a delay (the  K2's is a bit longer than the K3 and not 
adjustable).
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco