*We really suggest to always leave the transceiver's output power manual* *control to its maximum level because the EXPERT, thanks to its exclusive* *design, will provide to control that level as long as the required optimal* *value will be reached.* *Elecraft has only to implement a very fast input able to deal with negative *voltages as all the other manufacturers already do: SPE's amplifier will* *adapt to that in order to work for the best possible linearity.*
The ALC loop response can never be faster than group delay through the transmitter chain. While I have never measured the Elecraft filter, some crystal filters have a few mS delay. The propagation through the rest of the circuitry adds to the delay, as does the inevitable delay time in the actual ALC system. All of those delays, from the ALC control point forward to the ALC detection, and back from that point to the AGC controlled stage, add together. Elecraft did a VERY smart thing by having the ALC detection, or at least part of the ALC detection, ahead of the narrow filters and everything else. Running the radio full on and relying on the amplifier ALC would undo this, and may not bring the results assumed. Not only that, running other radios full on and depending 100% on amplifier ALC is probably not a good idea either. The less "stuff" between the power sampling point and the gain controlled stage, the better off we are. The whole reason some radios have overshoot is they run gain wide open and depend on a detector at the antenna port to reduce power, and the sum of delays from the gain controlled stage to the antenna, through the detector, through a comparator, and back to the gain controlled stage is what causes the problem in the first place. Moving the detection point out of the radio is never a benefit. I can't think of a reason in the world to use the amplifier ALC for anything other than a safety limit, especially with a rig like the K3 that does gain control and ALC ahead of the filters and components that cause most of the delay in the ALC loop. Can anyone else see why running the radio wide open and using 100% external detection is a good idea? 73 Tom ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
