David, The "magic" in your question has to do with the way the K3 (and the K2 if there are any listeners) control the power output. It has little to do with ALC, but has much to do with the amount of detected RF at the output. The K3 (K2) compares the measured RF output with the requested power and adjusts the drive level to try to make them equal. This is a closed loop control system.
Most other transceivers simply adjust the drive level without measuring the actual output, so the conventional wisdom works for those transceivers which use this open loop system. Elecraft is different and does not respond well to the "conventional wisdom". 73, Don W3FPR On 10/12/2012 11:10 PM, David Little wrote: > Don, > > That puts things into a better perspective. > > With that in mind, it does mimic normal ALC operation. > > I don't quite know how to interpret the instability in output while it is > measuring volume units, before it switches to ALC and stabilizes. > > > -----Original Message----- > From: Don Wilhelm [mailto:w3...@embarqmail.com] > Sent: Friday, October 12, 2012 11:01 PM > To: dalit...@bellsouth.net > Cc: Elecraft@mailman.qth.net > Subject: Re: [Elecraft] K3 Data Modes using SignaLink USB > > > David. > > I would like to point out that the K3 "ALC" indicator is also a level > indicator. The onset of ALC begins at the 5ht bar, and bars 1 through 4 > do not indicate any ALC action at all. They are more like a VU meter > provided to allow you some metering to help you adjust the audio level. > > 73, > Don W3FPR > > On 10/12/2012 10:19 PM, David Little wrote: >> Got my cable in today to do soundcard data modes on the K3 with a >> SignaLink USB >> >> Not much chance of getting the cabling incorrect, installation was >> uber easy. I used the rear panel inputs and outputs for the >> additional isolation; allowing me to keep the Mic on the front panel >> for mixed mode operation requirements. >> >> However, I am not having much luck finding a stable plateau to chance >> moving it off the dummy load and on the air. >> >> Output power isn't stable, and rises while the rig is in transmit. >> >> If power is changed while in transmit, it drops off, then starts >> building again. >> >> No power is generated until output level on the interface is high >> enough to generate ALC action. >> >> Not much chance of anything dependable here.... Where am I going >> wrong? >> >> I never run any ALC, unless it is an occasional flicker; usually a >> reference to decrease volume for a purer signal. >> >> Some prefer to run the output power to 25 watts and run 50% ALC, and >> share the signal up and down the band. >> >> I would prefer to set the power to a higher starting point, set the >> volume level correctly, then decrease the power, if necessary, >> maintaining a clean signal throughout. >> >> Anytime the power level on the K3 is changed at all, the output falls >> down and starts to build again. Around 30 to 45 seconds into a >> transmission, it may stabilize. >> >> I have used the SignaLink USB on a FT-897, FT-817, FTDX-9000MP, >> TS-2000, IC-756Pro II, IC-7000, IC-706, IC-7200, FT-857, FT-2000, >> Jupiter, IC-756 Pro, TS-870, TS-480.... And never experienced any >> instability of output before. >> >> Currently, I run them in the shack on a FT-897, FT-817, IC-756 Pro >> II, TS-2000 and the K3. The other rigs provide a stable digital >> platform >> >> When using a protocol where sync is dependent on the start of the >> transmission, the instability of power cannot be tolerated. >> >> I am a bit beyond RTTY and PSK-31 in the modes I need to run. The trend > I >> am operating toward now is in the direction of ARQ modes, and require >> a more refined approach than what I am seeing so far. >> >> I hope I am doing something wrong, and someone can provide some >> direction. >> >> David >> KD4NUE >> >> >> >> >> >> >> >> ______________________________________________________________ >> 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 >> > ______________________________________________________________ > 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 > ______________________________________________________________ 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
