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Re: [TenTec] din connector, etc.

To: tentec@contesting.com
Subject: Re: [TenTec] din connector, etc.
From: Jim Brown <k9yc@audiosystemsgroup.com>
Reply-to: k9yc@arrl.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Thu, 25 Sep 2014 12:12:22 -0700
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
On Thu,9/25/2014 9:02 AM, Roy wrote:
I operate everyday from 35 wpm to 45 wpm with QSK amplifiers. With the built-in Eagle keyer, transmitted weight is perfectly adjustable internally and with an external key or keyboard, weight is also perfectly adjustable using the weight controls on the external keyer to compensate for truncating effect of the 17ms. And again, of course Eagle works QSK with QSK amps.!!!

Thinking more about this -- the ARRL scope traces compare the RF output of the rig with the keying signal. This is NOT the same as the output of a power amp being keyed by the radio.

I think we need to define a QSK amplifier. There is more than one way to do it. The original Ten Tec way -- you key the Titan and the Titan keys the radio. The limitation of this setup is that the rig must have a very short delay on the RF signal. All amps, including the Titans, accept a DC keying signal (either a DC short or +DC). As Rick has noted, amps with vacuum relays switch very quickly, and can follow keying to fairly high speeds.

And there's also the matter of what does the operator listen to in order to decide if his keying is being shortened. If he listen to sidetone in his headphones, that is generated in the rig, and does NOT accurately represent the actual output of the rig or the amp. It's only what he's TRYING to send with his keyer or key. To hear what we are ACTUALLY sending, we must listen on a second radio (with no antenna connected and the RF gain turned all the way down)!

Looking at ARRL test reports for the Eagle and the TS590S -- the "TX to RX turnaround time" for the Eagle is 70 msec" and 20 msec for the 590. So, as Rick noted, at high keying speeds we're not going to hear between the dits, even barefoot. For both rigs, there's no shortening of the dits in full QSK at 60 wpm, and if the key signal to the power amp is coincident with the keying signal to the rig, an amp with a vacuum relay or diode switching should reproduce the keying waveforms, while an amp with open frame relays is likely to hot switch (unless there's a speedup circuit).

73, Jim K9YC


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