No CW QSK with ATU?

Jim KJ3P

This may be a continuing issue that I've missed until now, but:

I set CW Delay to 10, then activate the ATU, the delay changes to 81 when tuning is finished. If I then turn the ATU off, the delay returns to 10. So the practical minimum delay is 81 when using the ATU, with QSK operation and low delay values eliminated?

BTW, if I leave the ATU off, and use an external tuner, the CW delay & full QSK are OK.

[8600, v4.0.1+EA, Settings: TX Delay at zero]

--Jim KJ3P

Mike-VA3MW

I believe that is how it works currently.

Dan Trainor

With QSK turned on and ATU off (bypassed), the radio uses pin diodes for fast and quiet T/R switching. Then you can benefit from a very low delay setting. <10ms. That is if you prefer full break-in operation. Once you engage ATU, radio uses slower relay T/R switching and you will want to increase CW delay setting for semi breakin at a delay that works without dropping characters. I set mine to 250ms to avoid relay clatter and possibly increase the lifetime of the relays. Dan WA1QZX

Jim KJ3P

I've had Flex radios for years and never noticed this. Gotta pay more attention (or work more CW). Thanks for the info.

—jim

Mike-VA3MW

This might help. I had to go find it.

Note: When the transceiver is in QSK mode, reception occurs through the pre-selector which is
connected directly to the receiver’s analog to digital convertor (ADC). This provides the lowest loss
path to the ADC. Transmission with the ATU enabled sends the RF from the power amplifier
through the ATU before reaching the antenna connector. To avoid the ATU loading the receiver
during QSK operation, QSK is not available for single antenna ATU operation. If the ATU is required
during QSK operation, a separate receive antenna port (such as RX-A, RX-B, XVTR-A or XVTR-B)
must be employed.