FT8 HAM Radio - How to Reduce your ALC: The Secret to a Powerful Signal

Reducing your ALC in Digital modes.
This tip is so simple and overlooked. Its free.
Don't overdrive your radio in FT8 mode
I found a digital tip that a lot of people overlook - debate - are not sure of
I am using this with my Icom IC-7300
Some radios do require more ALC than others so try and see
I have thought about this for some time and in the digital microwave for broadcast TV overdriving is a No No. So it makes sense to not overdrive your HF signal on digital transmissions. Radios like the Icom IC-7300 has a very useful feature called audio
You can actually see if you are overdriving.
I used to run with the ALC just showing but if your do it with the Audio not overdriving there will be no ALC indicated on the radio.
#alc
#Digital Ham Radio
#DigitalAmateur
#FT8
#FT8off
#ham
#digital ham
#ALC
#IC-7300
#IC7300
#Icom
#WSJT
#HF
#over driving
#digitalsplatter
timecode
0:00 intro
01:14 Setup
02:46 Over driving
03:50 Normal Audio
Topical series hosted by Glenn VK2HTV
Thanks for watching! 73's !
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[@Aleziss]

It "clips" because of the level of the audio scope set at -20dB. Change the level of the audio scope and you won't get that "fake clipping" where you think the audio distort. Set the level at -30dB and you won't be fouled that the audio is distorting. The important thing in digital modes with the 7300 is to keep the ALC levels just before it starts registering on the ALC scale. For me it gives clean signal regardless of the mode you are using and I have success in all those modes like freedv, fldigi, varac and so on...

[@kf7bws]

Great explanation. This is what I have known and have tried to pass on for some time now. This is the first time I have seen it graphically and explained simply. Thank you.

[@russblahetka4742]

Thank you for a great video explanation on using FT8 on the 7300. I've heard a lot of conflicting information over the few years I've had the 7300, and your video really made a lot of sense.

[@robinmoseley766]

change the level on the audio scope - your audio scope can be altered. For AFSK Dta modes ..adjust the TX audio level so there is ALC action!! basic manual In the SSB mode, touch the TX meter to select the ALC meter, and adjust until the meter reading swings between 30 to 50% of the ALC scale, when speaking into the microphone at your normal voice level. advanced manual When operating in the SSB data mode, adjust the device’s output level to be within the ALC zone

[@FEPLabsRadio]

Glenn, this is awesome. I just did the same thing on 7610. Tweaked down even farther. THank you!

[@Aussie_Ham_Radio]

Thanks Jim - try it and see how it goes - I did some tests and for me on PSK reporter my reach was further than when i was in over drive mode.

[@thuff3207]

Sir, you are correct and over driving adds harmonics and that can make your signal hard to receive.

[@Aussie_Ham_Radio]

Thanks for the reply - Some people get upset on this advice but im going off my own experience

[@LB0FI]

Thank you, that was just so easy, and I made two DX contacts back to back after fiddling with this.

[@Aussie_Ham_Radio]

Awesome - Thanks for the comment. it is easy yea? I also have issues with audio settings on the computer - it’s a battle to tweak it perfect. But it’s what’s going out to the transmitter that is the key

[@Aussie_Ham_Radio]

Some hard comments are telling me im spreading lies by this - Im going off my own experiments where I wasn't even aware I was overdriving -0 I then reduced the ALC and PSK reporter reported contacts all over the place - so I am just passing on my own experience for people to try.- In Broadcast TV if we overdrive a microwave digital link signal it doesn't work as well as backing off the power

[@jose-medero7746]

Thanks for the thoughtful video and help others to improvement, thank you , keep the good work ❤

[@fotografm]

Excellent advice ! Will check this out on my 7300

[@Aussie_Ham_Radio]

Glad it was helpful! Some people get upset on this advice but im going off my own experience

[@pd9rd]

Very interesting, I have a different radio and never had a look on my audio scope, but that's what I'll be doing when on FT8. Thank you Glenn, 73.

[@Aussie_Ham_Radio]

Its worth a try - overdriving seems to be common

[@pd9rd]

@@Aussie_Ham_Radio Exactly, so I'll see how it goes keeping an eye on the ALC and audio scope. Thanks again! 73

[@jose-medero7746]

With your video I improved my contacts Log

[@damonkj7e]

Keep in mind, the displayed audio waveform is just a digital representation and not an actual measured waveform. The flattop distortion you are seeing is the limit in the vertical span of the audio meter, you can correct this by adding in more attenuation (your set to -20db level now). You need an external oscilloscope to see real TX waveform. Small amounts of ALC does not create flat top distortion as indicated in your video, it does drive the audio into compression. Edit, I came down to my shack to make a video demonstration using an external oscilloscope: kzbin.info/www/bejne/nmfKe62Zn5ZqrLc

[@Aussie_Ham_Radio]

Hi there thanks for your video - Just so you we are clear I didn't say run NO ALC I said to reduce the ALC so its not clipping. I think a lot of people clip the crap out of their signal. My purpose of the video was to encourage experimentation and see what happens if you reduce the ALC. The most important thing is how it works in the real world, and is the signal better? I turn compression off so my signal is a raw signal. A lot of people comment on the WSJT-X slider that is labelled a Power slider. I understand the audio meter on the 7300 - I don't have an oscilloscope to check the output. I didn't see that you have overdriven on your Yaesu radio as a fair comparison. In my experiment I found that my signal was being hampered if I had a lot of ALC and I could see the signal splatter somewhat. I also did a comparison of a high ALC and a low ALC and with PSK repeater my signal was received by more stations with the lower ALC. I wanted to make the point that some people don't need to drive that power slider all the way up to get a signal out. The fair way to test is to actually see the results in signal reports. Im not trying to trick people here but to get them also to experiment and maybe they don't need as much ALC as they think they need. I have also had people say they found that using less got them better results. It's the old Ham radio trick of doing more with less. I used to work in broadcast microwave links and in the digital links if we overdrive the signal it gets compromised. Im not exactly sure what you're showing in your video - could you do one that overdrives the signal? Could you do another video where your oscilloscope flat tops and then do a signal report comparison with something like PSK reporter and compare the difference between some ALC and a lot of ALC

[@damonkj7e]

@@Aussie_Ham_Radio Understood, my main point here was, the misinterpretation of the audio scope on the IC-7300, its being interrupted as distorted audio, but in realty it may not be, and in fact its only displaying a distorted waveform due to the limits of how the audio scope is setup. Last night I wanted to explore this subject a bit more, so I made a follow up video: kzbin.info/www/bejne/amHKnHh_hbeCf9k

[@temporarilyoffline]

This is great info and will help a lot of people!

[@Aussie_Ham_Radio]

Thanks Steve - always appreciate your support. Your very useful shows help to explore things like this

[@temporarilyoffline]

@@Aussie_Ham_Radio hams helping hams is what is all about!

[@vincentmartin2528]

Thanks for the video but I'm still a bit confused. As far as I know there are three settings to deal with for transmit. Playback (transmit) level from computer, Power level on radio, and output meter (level) Pwr slider on Wsjt-x. You show adjusting FT8 with the audio scope at -20db, but the scope clips if your change the scope settings, independent of the computer or FT8. So it doesn't seem like the right way to adjust the radio, especially concerning the power output and computer. Most everything I have read says to use the ALC as an indicator, not the audio scope. But I have yet to see a deffinitive process chain on how to setup the 7300 up properly.

[@homersaypian3798]

Thanks for the tip! Works on my FRDX-10 as well.

[@mm1dea]

Many thanks for the excellent info. I didn't realise how much i was overdriving the audio alc. 73 de MM1DEA

[@camworkstv]

Thank you for your video, Glenn. Apparently -20dB are set as attenuation for the display. Whether clipping already starts, or only the upper limit of the amplitude display is reached, seems questionable to me. I have set the attenuation in the display to -30dB as a test and there you can push the Pwr slider up to the upper limit stop without it clipping in the audio scope. Why did you just select the -20dB as the value, Glenn?

[@Aussie_Ham_Radio]

Thank you for the comment. I found that -20 monitor level was the best level monitoring, (which is the case in broadcast audio). I did some tests to see what the level looked like. What transmitted further out and what didn't. Have a look at the spectrum scope by itself zoomed in to the max when adjusting the power setting on WSJT-X. If your signal skirt looks spread out and especially if it has zig zags on it - its splattering. The higher you push that level up the larger the TX skirt gets and yes if you go to -30db the monitor will look lower on the audio scope. A nice clean signal is one that is not overdriving. If i have the nice rounded peaks on the -20 scale it doesn't splatter once i get above that switching to the spectrum display it does horrible things. To test properly you would need some bench equipment and failing that the internal scopes are adequate for Ham radio. Obviously this is for digital modes and the ALC is different when driving a HF radio using voice. I think a lot of people are basically running the input too high, it won't hurt to start lower before wacking the "PWR" slider to the roof. Audio is probably the hardest thing to get right between different computers. I think the slider is mis labelled calling it PWR have a separate monitor on the output I have lots of audio issues especially with Windows 11 where when you turn off enhancements they are still on - you have to go into the deeper menu that looks like windows 10 to turn off enhancements "again" there too. I also have issues on the latest Mac version of WSJT-X the level slider jumps around. I hope that explains it a bit better.

[@OutdoorsIQ]

This is an amazing explanation!

[@Capt_Duffy]

Very Nice, never knew about this.. 👍👍

[@Aussie_Ham_Radio]

Thanks I have tried it before but today I really sorted it out. I was always under the impression to just have some ALC showing. It’s way under even showing any. ALC on the meter. Video is still processing so it will be better quality soon

[@dfl19034]

On the IC-7300, via the Connectors menu, I adjusted the USB MOD Level to 25 (default is 50). This slider to 25 removed all ALC readings. I am able to keep the WSTT-X "power" slider just a notch below full. This seems to work for me. I have a DXCC challenge count of 1325.

[@AlvinMcManus]

I use the scope on my Yaesu FT-710 to verify the ALC meter reading. It's a very good idea.

[@paulvanderweegen7624]

Whenever I am running digital modes I always have no ALC showing, I leaned that 30 years ago using psk31, I now have a 7300 and never thought to use the audio scope to adjust the wave form. Great video and thanks for the tip.😊

[@gregmihran8616]

Interesting video Glenn! This is the best use case for the IC-7300 audio meter I've seen yet. I rarely have used it because I thought it was more of a fun gimmick. But I'm still struggling with why you selected -20dB on the audio waveform display. With this setting, my WSJT 'Pwr' meter is a much lower setting (-16 dB) than when I used my Meter ALC to determine the setting (-4.0 dB). And my IC-7300 draws much less power (8A versus 18A). I did read what u said about how broadcast audio uses that level and I do see how the signal skirt on the frequency spectrum extends out a bit. I'll keep trying this over an extended period of time to determine if it really does improve my FT8 response rate 😀73 KJ6ER

[@Aussie_Ham_Radio]

Thank you almost have to ignore that power slider. It’s a combination of what the audio meter and the alc on the radio. If you have a higher pwr setting in the software it clips and your actually wasting signal being compressed.

[@chiparip]

Applying this information made a HUGE difference in my FT8 signal. Stations that could never hear my signal before were easy to QSO once I got these audio settings optimized. And on 25% of the RF power. This clearly demonstrates how on SSB, modulation is EVERYTHING. KQ4NMY

[@Aussie_Ham_Radio]

Thanks for the feedback. I’ve had some negative comments about this. It’s worth trying to see if there is a difference. Overdriving a signal never works.

[@DO9KW]

Hi Glenn, a very interesting video. I also have the IC-7300 and use it daily for FT8 operation. Everything you say makes sense, I will also check my settings. I want to reduce/raise the output power of my 7300 without changing the ALC by moving the PWR slider in WSJT-X, is that possible? My Idea is to have 100W when the PWR slider is on the top and the ALC is a linear wave as shown in your video (I think you can set it in the windows audio settings). When turning down the PWR slider I want to reduce the output Power only - without (!) parallel lowering the ALC because then at some point the audio of my signal could get to "quiet". I hope you know what I mean ;) Maybe a video about your other settings - in combination with the ALC settings - would be a cool thing for a new video. 73s from Germany - DO9KW (Stefan)

[@Aussie_Ham_Radio]

It’s not perfect as you can change the value on the 7300 but if you know where the output sits it’s likely that your not overdriving. That’s the key to the input. I was finding too much alc was a too high “digital” signal. I backed it off and instantly got more replies on ft8

[@alleniceberg]

I have IC-746Pro. Is the mic gain the alc control?

[@ianbarton9359]

Great tutorial!!! I do have some comments/questions. I originally set my ALC up by pushing up the Pwr setting on WSJT-X to about midway and I had my IC7300 RF Power set to 60%. With these settings I was registering near enough to 60W on my SWR Power meter. When I followed your video I found out on Audio Scope of the IC7300 that I was overdriving so I backed off the Pwr setting until I was no longer clipping. When I did this my Power output dropped back to around 20W. To get 60W output I have to push up the Pwr slider which then reintroduces clipping. How can I get the full 60W output with clipping?

[@GoonyMclinux]

I have an older radio but I keep the transmit power on the radio at 100% and adjust the computer audio and software audio until its clean, 67 watts was about all I could get but 48 watts was my particular radios sweet spot for digital modes.

[@Aussie_Ham_Radio]

Are you looking at an external power meter ? Your power set by the radio won’t change. Have a look at something like psk reporter and it will show you the important thing if you are getting out

[@martysimon6428]

Hi. Thank you for the video. What do I do to reduce the audio. Is that the setting in WSJT where it has the power slider or a knob on the 7300. (I have the same radio) and I have only been able to reduce ALC by reducing power level in WSJT to point I have no output. Thank you. 73 WA5MS

[@KA4UPW]

What is your power output at this drive?

[@petermainwaringsx]

How are you adjusting the ALC?

[@revadan]

that depends on what frequency you are transmitting.. 400hz vs 2900hz has diff waveform ..

[@Siskiyous6]

The 7100 has that screen (At 1:47) in B/W. I hesitate to remove all the ALC off the meter, as I have had fair results. I guess I will experiment.

[@Aussie_Ham_Radio]

Yes you can see that screen and also tap the top right to cycle through the SWR so it can be seen on the Audio screen - on the 7300 anyway

[@Siskiyous6]

@@Aussie_Ham_Radio It has the 4 outputs and you can see the ALC, which was pretty high on my radio, I set it down in the WSJT-X PWR slider on the lower right, and my ALC is a lot lower now. And, I hit a bunch of central EU countries, ones I had had a tough time hitting before. The 7100 does not have the cool audio waveform display as far as I know. But I may dig through my owners manual tomorrow just in case it is there hiding. These radios are pretty advanced.

[@ReneAltena]

VK2 aitch TV, thanks.

[@2E0ILFhamradio]

When i lower the alc i lose output power too

[@Aussie_Ham_Radio]

Yes that is correct

[@stargazer7644]

How ironic. A video about how to make your radio sound better, yet the audio level on youtube is 13 dB down. Push the level button and that level meter will change scale and stop flat topping. Have you checked the actual transmitted audio?

[@Aussie_Ham_Radio]

Thanks for the feedback. I checked my settings and it sounds fine here when it was recoded and uploaded. It was recorded at 0vu and I check it on a LUFS meter at -9 LUFS and on a ppm at -12dB. Sometimes KZbin messes up the audio on stream delivery. It doesn’t have the same standard as broadcast so levels at your end can be wildly different - thanks

[@stargazer7644]

@@Aussie_Ham_Radio Right click the video, click stats for nerds, look at the Volume line (content loudness -12.9 dB) That tells you the average normalized video loudness as calculated by youtube (and as presented to the clients)

[@Aussie_Ham_Radio]

@@stargazer7644 Yep thanks for the feedback. I think it might be something on KZbin end. If anything my compressor on the mixer I’m using actually sounds high and maybe KZbin analyses it incorrectly. I’ll look into it more but I looked at the raw recording and audio is within broadcast spec. KZbin does weird compression things when I upload a video a hack I found is not to publish instantly but keep it private then publish once it reaches full servers otherwise the settings are forced for instance at 720p when it’s a 4K video. I actually think this video I put out quickly and while recorded correctly. But def need to find out more from my end. Thanks again for that feedback

[@VoeViking]

This is BS and you are spreading lies. You are not over driving nothing. Why are talking about something you know nothing about.

[@Aussie_Ham_Radio]

Thank you for your comment - You have no idea what I know about. I'm not sure if you have worked in professional transmission or professional audio. Happy to have a discussion if you know more about what part is BS according to you? Have you done tests? I have tested performance.

[@Aussie_Ham_Radio]

Telling lies? I think you should explain what lie im telling? Have you tried and tested this? Explain what part is a lie...