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Re: [wsjt-devel] FT4 & FT8 and ALC
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From: Roy G. <roy...@gm...> - 2019-06-13 16:25:19
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For what it's worth, I have a different view of how ALC works. First of all, I don't think that properly implemented ALC causes more than a trivial amount of distortion in the signal. Audio processors in studio sound boards and in commercial radio stations use it routinely. It has the benefit of stabilizing the audio level. The FT8 signal has constant amplitude so ALC does not have to work hard at all. It just sits there maintaining constant transmitter output power. I checked to see what the ALC was doing in my ICOM IC-7300 and saw that it was about 55%, which is perhaps a little too high. So I reduced the *Speakers (USB Audio CODEC)* from 20% to 15% and the ALC dropped to 45%. I am using the built in soundcard in the IC-7300. I am not having any problems in making contacts and I think that my signal is clean. To prove otherwise would require using laboratory instruments to test the signal... 73, Roy, W7IDM On Thu, Jun 13, 2019 at 8:47 AM Ryan Tourge <rya...@gm...> wrote: > I have used the following method regardless of radio used... > > Use an external power meter (after the transmitter). > > Adjust audio gain/drive until the point where power meter stops rising. At > this point, the radios ALC meter will start to show some deflection. Back > the audio back slightly. The power output will stay about the same and ALC > will be "0" on the radio's meter. > > Make contacts :) > > > On Thu, Jun 13, 2019 at 7:42 AM Black Michael via wsjt-devel < > wsj...@li...> wrote: > >> Only when the manual is correct. Most are wholly inadequate in this >> respect. Mainly due to not addressing digital modes at all. Even >> Kenwood's own TS-890S multi-lingual manual doesn't mention this. >> >> I just worked with a user yesterday with in IC-7000 and RigBlaster >> Advantage in the ACC socket and had to have the MIC level set at 1 and we >> could crank up the RigBlaster TX to get 90W without any ALC action on the >> rig. If we cranked up the MIC gain and turned down the RigBlaster TX we >> could get ALC action at 10W (note that the rig was always set at 100W). >> >> Any manual that talks about SSB Phone mode needs to be ignored as it has >> nothing to do with digital operations. >> >> My main point is that if you can get 90W without ALC indication you are >> pretty well guaranteed your signal is as clean as it can get. And I've >> been able to get 90W/No ALC on 99% of the rigs I've dealt with. >> >> de Mike W9MDB >> >> >> >> >> On Thursday, June 13, 2019, 01:06:46 AM CDT, Roeland Jansen < >> roe...@gm...> wrote: >> >> >> so we agree that we should follow the manuals of the manufacturers? >> >> On Wed, Jun 12, 2019 at 4:56 PM Black Michael via wsjt-devel < >> wsj...@li...> wrote: >> >> I finally got a reply from Kenwood for the TS-990S -- this quite likely >> applies to all the Kenwood's with the red ALC zone. >> The bottom of the meter is 0dB ALC. I would maintain once you see the >> "beings to swing" you back off a bit for no swing. >> You won't find the PSK31 words in the multi-lingual manual...it's in the >> English manual (and perhaps the other individual languages). >> It tells you to set the rig for almost no ALC indication. >> >> de Mike W9MDB >> >> Regarding the ALC 0dB and +6dB, refer to the picture below. >> >> >> >> >> >> In the TS-990S instruction manual, it is mentioned as follows. >> --------------------------------------------- >> In the case of operation in the digital mode such as PSK31 using >> a PC, you must adjust the audio output level from PC until the ALC >> meter of the transceiver begins to swing. >> --------------------------------------------- >> The level "begins to swing" is not zone max (+6dB) but threshold 0dB. >> >> >> On Thursday, June 6, 2019, 01:09:07 AM CDT, Wolfgang <oe...@gm...> >> wrote: >> >> >> There is a common belief that became an internalized misentrepretation: >> >> "NO ALC", or even "ALC is bad", this can not be applied to all rigs. On a >> Kenwood rig the manual says, you should not go (drive) the rig beyond the >> red bar. >> >> For example, the Kenwood TS990 audio input setting to "no ALC" will >> result >> in an Power output that goes down to indeterminable value, compared to >> the >> Po setting on the front panel knob & meter. >> >> So please consult your rigs manual, the designers gave you the right >> info. >> >> 73 de Wolfgang >> OE1MWW >> >> ---------- >> Amateur radio is the most expensive type of free-of-charge communication! >> Amateurfunk ist die teuerste Art der kostenlosen Kommunikation! >> _______________________________________________ >> wsjt-devel mailing list >> wsj...@li... >> https://lists.sourceforge.net/lists/listinfo/wsjt-devel >> _______________________________________________ >> wsjt-devel mailing list >> wsj...@li... >> https://lists.sourceforge.net/lists/listinfo/wsjt-devel >> >> _______________________________________________ >> wsjt-devel mailing list >> wsj...@li... >> https://lists.sourceforge.net/lists/listinfo/wsjt-devel >> > _______________________________________________ > wsjt-devel mailing list > wsj...@li... > https://lists.sourceforge.net/lists/listinfo/wsjt-devel > |
