locked ALC Levels on non-Elecraft Radios - History? #transmit


Steve Kavanagh
 

There seems to be "received wisdom" that for non-Elecraft radios one must operate WSJT-X modes with no ALC action. Having recently acquired a new Yaesu radio, I found a variety of videos and reflector postings instructing that this is the way to operate my radio on FT8, etc. Yet, my own experimentation has shown (at least to my initial satisfaction) that ALC action in itself does not appear to cause any significant degradation of the signal quality, so long as the various audio levels and gains are adjusted correctly.

I am just wondering how this got started. Are there rigs with ALC action that is so fast as to cause significant audio distortion, other than maybe very briefly at the start of transmission? Is it still true for modern Yaesu's and I'm missing something, perhaps of a transient or dynamic nature?

73,
Steve VE3SMA


Eric Urban
 

Steve,

What Yaesu model are you referring to specifically?

Eric
KK4KYE

On Mon, Jan 3, 2022 at 9:18 AM Steve Kavanagh via groups.io <sjkavanagh1=
yahoo.ca@groups.io> wrote:

There seems to be "received wisdom" that for non-Elecraft radios one must
operate WSJT-X modes with no ALC action. Having recently acquired a new
Yaesu radio, I found a variety of videos and reflector postings instructing
that this is the way to operate my radio on FT8, etc. Yet, my own
experimentation has shown (at least to my initial satisfaction) that ALC
action in itself does not appear to cause any significant degradation of
the signal quality, so long as the various audio levels and gains are
adjusted correctly.

I am just wondering how this got started. Are there rigs with ALC action
that is so fast as to cause significant audio distortion, other than maybe
very briefly at the start of transmission? Is it still true for modern
Yaesu's and I'm missing something, perhaps of a transient or dynamic nature?

73,
Steve VE3SMA






Michael Black
 

Nothing to do with transients.
Has to do with rig calibration, ALC feedback circuit, and the level at which ALC starts attenuating the signal.     Then it is how does that level relate to clipping the audio.  So does ALC start at 1V or 0.9V or 1.1V?  It's all variable.Elecraft calibrates theirs to approx 4 bars of ALC is 0dB.
The logical approach is simple....you increase your audio level into the rig via the rig gain, the audio device gain, and 0dB on the computer until you get approx 90% of the rig's power setting.I have yet to see a rig that generates ALC if you are putting 40W into a rig set at 50W.What you'll see is as you approach 50W the ALC will start increasing....generally I would think you won't
Mike W9MDB

On Monday, January 3, 2022, 09:18:27 AM CST, Steve Kavanagh via groups.io <sjkavanagh1=yahoo.ca@groups.io> wrote:

There seems to be "received wisdom" that for non-Elecraft radios one must operate WSJT-X modes with no ALC action.  Having recently acquired a new Yaesu radio, I found a variety of videos and reflector postings instructing that this is the way to operate my radio on FT8, etc.  Yet, my own experimentation has shown (at least to my initial satisfaction) that ALC action in itself does not appear to cause any significant degradation of the signal quality, so long as the various audio levels and gains are adjusted correctly.

I am just wondering how this got started.  Are there rigs with ALC action that is so fast as to cause significant audio distortion, other than maybe very briefly at the start of transmission?  Is it still true for modern Yaesu's and I'm missing something, perhaps of a transient or dynamic nature?

73,
Steve VE3SMA


Sam Birnbaum
 

Great answer Mike.
73,

Sam W2JDB

-----Original Message-----
From: Michael Black via groups.io <mdblack98=yahoo.com@groups.io>
To: main@wsjtx.groups.io <main@wsjtx.groups.io>; main@WSJTX.groups.io <main@wsjtx.groups.io>
Sent: Mon, Jan 3, 2022 10:58 am
Subject: Re: [WSJTX] ALC Levels on non-Elecraft Radios - History? #transmit

Nothing to do with transients.
Has to do with rig calibration, ALC feedback circuit, and the level at which ALC starts attenuating the signal.     Then it is how does that level relate to clipping the audio.  So does ALC start at 1V or 0.9V or 1.1V?  It's all variable.Elecraft calibrates theirs to approx 4 bars of ALC is 0dB.
The logical approach is simple....you increase your audio level into the rig via the rig gain, the audio device gain, and 0dB on the computer until you get approx 90% of the rig's power setting.I have yet to see a rig that generates ALC if you are putting 40W into a rig set at 50W.What you'll see is as you approach 50W the ALC will start increasing....generally I would think you won't
Mike W9MDB

    On Monday, January 3, 2022, 09:18:27 AM CST, Steve Kavanagh via groups.io <sjkavanagh1=yahoo.ca@groups.io> wrote: 

There seems to be "received wisdom" that for non-Elecraft radios one must operate WSJT-X modes with no ALC action.  Having recently acquired a new Yaesu radio, I found a variety of videos and reflector postings instructing that this is the way to operate my radio on FT8, etc.  Yet, my own experimentation has shown (at least to my initial satisfaction) that ALC action in itself does not appear to cause any significant degradation of the signal quality, so long as the various audio levels and gains are adjusted correctly.

I am just wondering how this got started.  Are there rigs with ALC action that is so fast as to cause significant audio distortion, other than maybe very briefly at the start of transmission?  Is it still true for modern Yaesu's and I'm missing something, perhaps of a transient or dynamic nature?

73,
Steve VE3SMA


Michael Black
 

I should have also said....
If you can generate 90W into your rig set at 100W with no ALC is the extra 10W going to really help?  The answer is no.
Unless you can monitor your own signal to ensure you do not have harmonics that 0dB ALC point is where you should stick.  The trick is finding that 0dB ALC point.
I'll have to do this experiment on my IC706MKIIG and Omni VII which are both analog audio and easy to overdrive.
Mike W9MDB

On Monday, January 3, 2022, 10:20:51 AM CST, Sam Birnbaum via groups.io <w2jdb=aol.com@groups.io> wrote:

Great answer Mike.
73,

Sam W2JDB


-----Original Message-----
From: Michael Black via groups.io <mdblack98=yahoo.com@groups.io>
To: main@wsjtx.groups.io <main@wsjtx.groups.io>; main@WSJTX.groups.io <main@wsjtx.groups.io>
Sent: Mon, Jan 3, 2022 10:58 am
Subject: Re: [WSJTX] ALC Levels on non-Elecraft Radios - History? #transmit

Nothing to do with transients.
Has to do with rig calibration, ALC feedback circuit, and the level at which ALC starts attenuating the signal.     Then it is how does that level relate to clipping the audio.  So does ALC start at 1V or 0.9V or 1.1V?  It's all variable.Elecraft calibrates theirs to approx 4 bars of ALC is 0dB.
The logical approach is simple....you increase your audio level into the rig via the rig gain, the audio device gain, and 0dB on the computer until you get approx 90% of the rig's power setting.I have yet to see a rig that generates ALC if you are putting 40W into a rig set at 50W.What you'll see is as you approach 50W the ALC will start increasing....generally I would think you won't
Mike W9MDB

    On Monday, January 3, 2022, 09:18:27 AM CST, Steve Kavanagh via groups.io <sjkavanagh1=yahoo.ca@groups.io> wrote: 

There seems to be "received wisdom" that for non-Elecraft radios one must operate WSJT-X modes with no ALC action.  Having recently acquired a new Yaesu radio, I found a variety of videos and reflector postings instructing that this is the way to operate my radio on FT8, etc.  Yet, my own experimentation has shown (at least to my initial satisfaction) that ALC action in itself does not appear to cause any significant degradation of the signal quality, so long as the various audio levels and gains are adjusted correctly.

I am just wondering how this got started.  Are there rigs with ALC action that is so fast as to cause significant audio distortion, other than maybe very briefly at the start of transmission?  Is it still true for modern Yaesu's and I'm missing something, perhaps of a transient or dynamic nature?

73,
Steve VE3SMA


Joe Subich, W4TV
 

On 2022-01-03 11:26 AM, Michael Black via groups.io wrote:
I should have also said....
If you can generate 90W into your rig set at 100W with no ALC is the extra 10W going to really help? The answer is no.
Almost every rig with a 12V final amplifier (most all 100W rigs) is
pushing the 1 dB compression point of the final amplifier devices
at 80W (PEP) output. If the rig is properly aligned, that 1dB
compression point is very close to the "onset of ALC" ...

Even if one does not have *AUDIO* artifacts, final amplifier clipping
(harmonics) and IMD (adjacent channel distortion) start to rise very
quickly once one has exceeded 1dB of compression in the final amplifier
(and some analog rigs reach 1dB of compression in the IF stages even
earlier if they are not properly aligned!).

73,

... Joe, W4TV


On 2022-01-03 11:26 AM, Michael Black via groups.io wrote:
I should have also said....
If you can generate 90W into your rig set at 100W with no ALC is the extra 10W going to really help?  The answer is no.
Unless you can monitor your own signal to ensure you do not have harmonics that 0dB ALC point is where you should stick.  The trick is finding that 0dB ALC point.
I'll have to do this experiment on my IC706MKIIG and Omni VII which are both analog audio and easy to overdrive.
Mike W9MDB
On Monday, January 3, 2022, 10:20:51 AM CST, Sam Birnbaum via groups.io <w2jdb=aol.com@groups.io> wrote:
Great answer Mike.
73,
Sam W2JDB
-----Original Message-----
From: Michael Black via groups.io <mdblack98=yahoo.com@groups.io>
To: main@wsjtx.groups.io <main@wsjtx.groups.io>; main@WSJTX.groups.io <main@wsjtx.groups.io>
Sent: Mon, Jan 3, 2022 10:58 am
Subject: Re: [WSJTX] ALC Levels on non-Elecraft Radios - History? #transmit
Nothing to do with transients.
Has to do with rig calibration, ALC feedback circuit, and the level at which ALC starts attenuating the signal.     Then it is how does that level relate to clipping the audio.  So does ALC start at 1V or 0.9V or 1.1V?  It's all variable.Elecraft calibrates theirs to approx 4 bars of ALC is 0dB.
The logical approach is simple....you increase your audio level into the rig via the rig gain, the audio device gain, and 0dB on the computer until you get approx 90% of the rig's power setting.I have yet to see a rig that generates ALC if you are putting 40W into a rig set at 50W.What you'll see is as you approach 50W the ALC will start increasing....generally I would think you won't
Mike W9MDB
    On Monday, January 3, 2022, 09:18:27 AM CST, Steve Kavanagh via groups.io <sjkavanagh1=yahoo.ca@groups.io> wrote:
There seems to be "received wisdom" that for non-Elecraft radios one must operate WSJT-X modes with no ALC action.  Having recently acquired a new Yaesu radio, I found a variety of videos and reflector postings instructing that this is the way to operate my radio on FT8, etc.  Yet, my own experimentation has shown (at least to my initial satisfaction) that ALC action in itself does not appear to cause any significant degradation of the signal quality, so long as the various audio levels and gains are adjusted correctly.
I am just wondering how this got started.  Are there rigs with ALC action that is so fast as to cause significant audio distortion, other than maybe very briefly at the start of transmission?  Is it still true for modern Yaesu's and I'm missing something, perhaps of a transient or dynamic nature?
73,
Steve VE3SMA


Alan G4ZFQ
 

I am just wondering how this got started. Are there rigs with ALC action that is so fast as to cause significant audio distortion,
Steve,

Another thing, maybe more useful for QRP, is that if ALC is not working then the WSJT-X power slider will reduce power linearly.

73 Alan G4ZFQ


Michael Black
 

That's one thing I do with everybody I work with is ensure linear operation.
So if you have 100W at full scale in WSJT-X then taking the power slider down in 3db increments will halve the power each time.
So
-3dB = 50W-6dB = 25W-9dB = 12W
If you don't get that first -3db=50W then you are not in the linear operating range of your rig. 
Mike W9MDB



On Monday, January 3, 2022, 11:20:50 AM CST, Alan G4ZFQ <alan4alan@gmail.com> wrote:

> I am just wondering how this got started.  Are there rigs with ALC action that is so fast as to cause significant audio distortion,

Steve,

Another thing, maybe more useful for QRP, is that if ALC is not working
then the WSJT-X power slider will reduce power linearly.

73 Alan G4ZFQ


mattwood2000@...
 

Hi Steve,

I've been running my FT-897D remotely in the garage with rigctld and
network audio streams. This works OK and while I haven't had reports
of audio issues, I haven't had a chance to set up another rig to truly
analyze my transmit audio. But, I did notice the 897 does seem to be
a bit heavy on the ALC according to its display depending on the FT8
TX audio frequency.

Slightly off topic but might be relevant to your setup. The 8x7 rigs
seem to have hidden CAT support for ALC, not sure about others:

http://www.ka7oei.com/ft817_meow.html

Attached is a patch for Hamlib to add ALC support to the 897. It's a
hack but does work. Not sure which Yaesu you run, but you might be
able to adapt this to your rig and needs.

73, Matt - N1YQE


On Mon, Jan 3, 2022 at 10:18 AM Steve Kavanagh via groups.io
<sjkavanagh1=yahoo.ca@groups.io> wrote:

There seems to be "received wisdom" that for non-Elecraft radios one must operate WSJT-X modes with no ALC action. Having recently acquired a new Yaesu radio, I found a variety of videos and reflector postings instructing that this is the way to operate my radio on FT8, etc. Yet, my own experimentation has shown (at least to my initial satisfaction) that ALC action in itself does not appear to cause any significant degradation of the signal quality, so long as the various audio levels and gains are adjusted correctly.

I am just wondering how this got started. Are there rigs with ALC action that is so fast as to cause significant audio distortion, other than maybe very briefly at the start of transmission? Is it still true for modern Yaesu's and I'm missing something, perhaps of a transient or dynamic nature?

73,
Steve VE3SMA





Michael Black
 

Thanks for the patch -- it's been applied to hamlib.
Mike W9MDB

On Monday, January 3, 2022, 11:34:56 AM CST, mattwood2000@gmail.com <mattwood2000@gmail.com> wrote:

Hi Steve,

I've been running my FT-897D remotely in the garage with rigctld and
network audio streams.  This works OK and while I haven't had reports
of audio issues, I haven't had a chance to set up another rig to truly
analyze my transmit audio.  But, I did notice the 897 does seem to be
a bit heavy on the ALC according to its display depending on the FT8
TX audio frequency.

Slightly off topic but might be relevant to your setup.  The 8x7 rigs
seem to have hidden CAT support for ALC, not sure about others:

http://www.ka7oei.com/ft817_meow.html

Attached is a patch for Hamlib to add ALC support to the 897. It's a
hack but does work.  Not sure which Yaesu you run, but you might be
able to adapt this to your rig and needs.

73, Matt - N1YQE


On Mon, Jan 3, 2022 at 10:18 AM Steve Kavanagh via groups.io
<sjkavanagh1=yahoo.ca@groups.io> wrote:

There seems to be "received wisdom" that for non-Elecraft radios one must operate WSJT-X modes with no ALC action.  Having recently acquired a new Yaesu radio, I found a variety of videos and reflector postings instructing that this is the way to operate my radio on FT8, etc.  Yet, my own experimentation has shown (at least to my initial satisfaction) that ALC action in itself does not appear to cause any significant degradation of the signal quality, so long as the various audio levels and gains are adjusted correctly.

I am just wondering how this got started.  Are there rigs with ALC action that is so fast as to cause significant audio distortion, other than maybe very briefly at the start of transmission?  Is it still true for modern Yaesu's and I'm missing something, perhaps of a transient or dynamic nature?

73,
Steve VE3SMA





Steve Kavanagh
 

Thanks for all the input. But I am afraid I don't really follow....so keep it coming, please.

In most WSJT-X modes the amplitude is constant, so there is absolutely no need for RF amplification to be linear (maybe linear will help in MSK144 to some degree, in practice, if not in simple theory). A Class C or D amp will work just as well as a linear one, with the exception perhaps of some "key clicks" at the beginning and end of each transmission. No intermod is generated by a non-linear amp when the signal is a single frequency at a time, like FT8, for example

But the audio amplification definitely has to be very linear to avoid creating audio harmonics.

If ALC works instantaneously - in other words it directly clips the audio, with no time constants involved, then it will generate audio harmonics. If it works more slowly (like AGC in a receiver) then it might generate some distortion due to a fast attack time (perhaps for a few milliseconds at the beginning of a transmission), but then it ought to settle down to a reduced value of linear audio amplification. I thought ALC was normally the latter - fast attack, slow decay. Am I wrong?

Yes, Alan (G4ZFQ), I suppose if you are trying to set milliwatt transmit powers from a rig that will normally only go down to 5 watts, say, it would be useful to operate with no ALC so the output is proportional to the input in every way.

73,
Steve VE3SMA


Michael Black
 

We aren't talking about the amplifier linearity -- we're talking about the rig's power level being linear with the input audio data.  That's how you ensure you aren't into the ALC compression.It all depends on how the engineers design their ALC circuit.
So this for example going to the rig in digital format over a USB cable....skip the digital part if you're using an audio device like SignaLink or RigBlaster.Not that voltage here is a representation of -1 to 1V and is arbitrary at this point but typical values used for digital audio levels.Note that a command situation for over driving is people feeding MIC inputs with Line or Speaker level voltages.  MIC's operating at 100 millivolt levels and below which is far below the line levels of 1V and speaker levels of 10V or more.
32767 = 1V  (yes -- it's not 32768 -- 16-bit audio range is -32768 to 32767 or 0x1000 to 0x7FFF16384 = 0.5V = -3dB8192 = 0.25V = -6dB4096 = 0.125V = -9dB
Mike W9MDB

On Monday, January 3, 2022, 11:51:16 AM CST, Steve Kavanagh via groups.io <sjkavanagh1=yahoo.ca@groups.io> wrote:

Thanks for all the input.  But I am afraid I don't really follow....so keep it coming, please. 

In most WSJT-X modes the amplitude is constant, so there is absolutely no need for RF amplification to be linear (maybe linear will help in MSK144 to some degree, in practice, if not in simple theory). A Class C or D amp will work just as well as a linear one, with the exception perhaps of some "key clicks" at the beginning and end of each transmission.  No intermod is generated by a non-linear amp when the signal is a single frequency at a time, like FT8, for example

But the audio amplification definitely has to be very linear to avoid creating audio harmonics.

If ALC works instantaneously - in other words it directly clips the audio, with no time constants involved, then it will generate audio harmonics.  If it works more slowly (like AGC in a receiver) then it might generate some distortion due to a fast attack time (perhaps for a few milliseconds at the beginning of a transmission), but then it ought to settle down to a reduced value of linear audio amplification.  I thought ALC was normally the latter - fast attack, slow decay.  Am I wrong?

Yes, Alan (G4ZFQ), I suppose if you are trying to set milliwatt transmit powers from a rig that will normally only go down to 5 watts, say, it would be useful to operate with no ALC so the output is proportional to the input in every way.

73,
Steve VE3SMA


 

Ys Michael,

That is basically how I sorted out the TX Audio pathway. Upped the AF audio until the RF ceased to increase and backed off a bit. The IC-7300 ALC meter was just shy of the middle mark.

73 Phil GM3ZZA

Sent from Mail for Windows

From: Michael Black via groups.io
Sent: 03 January 2022 18:05
To: main@wsjtx.groups.io; main@WSJTX.groups.io
Subject: Re: [WSJTX] ALC Levels on non-Elecraft Radios - History? #transmit

We aren't talking about the amplifier linearity -- we're talking about the rig's power level being linear with the input audio data.  That's how you ensure you aren't into the ALC compression.It all depends on how the engineers design their ALC circuit.
So this for example going to the rig in digital format over a USB cable....skip the digital part if you're using an audio device like SignaLink or RigBlaster.Not that voltage here is a representation of -1 to 1V and is arbitrary at this point but typical values used for digital audio levels.Note that a command situation for over driving is people feeding MIC inputs with Line or Speaker level voltages.  MIC's operating at 100 millivolt levels and below which is far below the line levels of 1V and speaker levels of 10V or more.
32767 = 1V  (yes -- it's not 32768 -- 16-bit audio range is -32768 to 32767 or 0x1000 to 0x7FFF16384 = 0.5V = -3dB8192 = 0.25V = -6dB4096 = 0.125V = -9dB
Mike W9MDB




On Monday, January 3, 2022, 11:51:16 AM CST, Steve Kavanagh via groups.io <sjkavanagh1=yahoo.ca@groups.io> wrote:

Thanks for all the input.  But I am afraid I don't really follow....so keep it coming, please. 

In most WSJT-X modes the amplitude is constant, so there is absolutely no need for RF amplification to be linear (maybe linear will help in MSK144 to some degree, in practice, if not in simple theory). A Class C or D amp will work just as well as a linear one, with the exception perhaps of some "key clicks" at the beginning and end of each transmission.  No intermod is generated by a non-linear amp when the signal is a single frequency at a time, like FT8, for example

But the audio amplification definitely has to be very linear to avoid creating audio harmonics.

If ALC works instantaneously - in other words it directly clips the audio, with no time constants involved, then it will generate audio harmonics.  If it works more slowly (like AGC in a receiver) then it might generate some distortion due to a fast attack time (perhaps for a few milliseconds at the beginning of a transmission), but then it ought to settle down to a reduced value of linear audio amplification.  I thought ALC was normally the latter - fast attack, slow decay.  Am I wrong?

Yes, Alan (G4ZFQ), I suppose if you are trying to set milliwatt transmit powers from a rig that will normally only go down to 5 watts, say, it would be useful to operate with no ALC so the output is proportional to the input in every way.

73,
Steve VE3SMA


Michael Black
 

That sounds correct for the 7300 -- which, by the way, is just about impossible to overdrive though the USB connection.We tested turning up the audio gain to max and still didn't see harmonics.
Mike W9MDB

On Monday, January 3, 2022, 01:02:08 PM CST, Philip Rose via groups.io <gm3zza=btinternet.com@groups.io> wrote:

Ys Michael,

That is basically how I sorted out the TX Audio pathway. Upped the AF audio until the RF ceased to increase and backed off a bit. The IC-7300 ALC meter was just shy of the  middle mark.

73 Phil GM3ZZA

Sent from Mail for Windows

From: Michael Black via groups.io
Sent: 03 January 2022 18:05
To: main@wsjtx.groups.io; main@WSJTX.groups.io
Subject: Re: [WSJTX] ALC Levels on non-Elecraft Radios - History? #transmit

We aren't talking about the amplifier linearity -- we're talking about the rig's power level being linear with the input audio data.  That's how you ensure you aren't into the ALC compression.It all depends on how the engineers design their ALC circuit.
So this for example going to the rig in digital format over a USB cable....skip the digital part if you're using an audio device like SignaLink or RigBlaster.Not that voltage here is a representation of -1 to 1V and is arbitrary at this point but typical values used for digital audio levels.Note that a command situation for over driving is people feeding MIC inputs with Line or Speaker level voltages.  MIC's operating at 100 millivolt levels and below which is far below the line levels of 1V and speaker levels of 10V or more.
32767 = 1V  (yes -- it's not 32768 -- 16-bit audio range is -32768 to 32767 or 0x1000 to 0x7FFF16384 = 0.5V = -3dB8192 = 0.25V = -6dB4096 = 0.125V = -9dB
Mike W9MDB




    On Monday, January 3, 2022, 11:51:16 AM CST, Steve Kavanagh via groups.io <sjkavanagh1=yahoo.ca@groups.io> wrote: 

Thanks for all the input.  But I am afraid I don't really follow....so keep it coming, please. 

In most WSJT-X modes the amplitude is constant, so there is absolutely no need for RF amplification to be linear (maybe linear will help in MSK144 to some degree, in practice, if not in simple theory). A Class C or D amp will work just as well as a linear one, with the exception perhaps of some "key clicks" at the beginning and end of each transmission.  No intermod is generated by a non-linear amp when the signal is a single frequency at a time, like FT8, for example

But the audio amplification definitely has to be very linear to avoid creating audio harmonics.

If ALC works instantaneously - in other words it directly clips the audio, with no time constants involved, then it will generate audio harmonics.  If it works more slowly (like AGC in a receiver) then it might generate some distortion due to a fast attack time (perhaps for a few milliseconds at the beginning of a transmission), but then it ought to settle down to a reduced value of linear audio amplification.  I thought ALC was normally the latter - fast attack, slow decay.  Am I wrong?

Yes, Alan (G4ZFQ), I suppose if you are trying to set milliwatt transmit powers from a rig that will normally only go down to 5 watts, say, it would be useful to operate with no ALC so the output is proportional to the input in every way.

73,
Steve VE3SMA


Roger
 

There's also Bill's instructions for setting up the ALC levels here:-
https://wsjtx.groups.io/g/main/topic/setting_windows_wsjt_x_tx/75435187?p=,,,20,0,0,0::recentpostdate/sticky,,,20,2,0,75435187,previd=9223372036854775807,nextid=1641063108371347942&previd=9223372036854775807&nextid=1641063108371347942

73
Roger
GW4HZA


SteveO
 

I have FT-891 and FT-991a radios. Not sure the "proper" way to run FT8, but Yaesu / WSJT-X manuals basically recommend adjusting for minimal ALC.

Because the FT-891 can only show one meter at a time on the front panel and that I was writing my own CAT control program, I added the ability to monitor SWR, Power Out, ALC and Idd meters from my application.

Interestingly, you do not need to see all of the meters however seeing them confirmed what I suspected/observed from before.

Example:
* Set the RF output to say 20 Watts
* Send a WSPR or FT8 call and observe power out.
- if it is less than 20 Watts, then adjust WSJT-X power setting upwards until the radio shows 20W (or maxes out)
- if it is 20 watts, then adjust WSJT-X power setting downwards until the radio drops below 20W and then push up a little bit to keep the power out at 20W

This is how I did it before I could see all meters at once. Turns out, even though you are seeing all of the meters, that method is what you ultimately end up doing to ensure you are outputting the expected power out and keeping ALC within the radio's recommendations.

Best regards,
Steve O de KC5NK


Rick McNamara
 

It may be that Radio suppliers could not get the majority of users to
understand fine tuning the way you know how to do it, so the supplied
advice became to have the user shut it off.

On Mon, Jan 3, 2022 at 7:18 AM Steve Kavanagh via groups.io <sjkavanagh1=
yahoo.ca@groups.io> wrote:

There seems to be "received wisdom" that for non-Elecraft radios one must
operate WSJT-X modes with no ALC action. Having recently acquired a new
Yaesu radio, I found a variety of videos and reflector postings instructing
that this is the way to operate my radio on FT8, etc. Yet, my own
experimentation has shown (at least to my initial satisfaction) that ALC
action in itself does not appear to cause any significant degradation of
the signal quality, so long as the various audio levels and gains are
adjusted correctly.

I am just wondering how this got started. Are there rigs with ALC action
that is so fast as to cause significant audio distortion, other than maybe
very briefly at the start of transmission? Is it still true for modern
Yaesu's and I'm missing something, perhaps of a transient or dynamic nature?

73,
Steve VE3SMA





--
*WS7PB*
*Who is John Galt?*


Steve Kavanagh
 

To answer Eric (KK4KYE), my new Yaesu is an FTDX10.

It is really, really easy to overload the transmit audio if the input is through the USB route - several owners have complained about audio harmonics on the FTDX10 groups. It seems like there ought to be an attenuator between the USB CODEC and the transmit audio section which isn't there. But it appears that it is also not too hard to get it pretty clean. With good audio level settings, I have been using it much as Phil (GM3ZZA) suggested for the IC-7300...the ALC meter ends up around the middle of the "good" range or a bit above.

I just did a test using my old Elecraft K2's receiver feeding another computer running WSJT-X to monitor the FTDX10 output (running into a dummy load). So far, I have been able to receive the signal at a report of +32 dB without being able to make out the audio harmonics in the Wide Graph. They appear to be below -50 dB with respect to the desired signal on the rig's built-in SDR which does operate while transmitting. This is running the full rated 100 W on 80m FT8, with ALC at about half way up the "good" part of the scale, audio frequency of 801 Hz and Split Operations = None, to make sure that any harmonics would be within the transmit bandwidth. If I add some inches of antenna to the K2 I can clearly see the 2nd harmonic, but the signal report appears to top out at +34, so this isn't too quantitatively meaningful. Anyway, it doesn't seem too bad and will, of course, improve with Split Operations = Fake It.

So at least for some modern rigs such as the the IC-7300 and FTDX10, it seems the general advice to keep the ALC at zero is not quite accurate, which is what made me curious about the history.

73,
Steve VE3SMA


Alan G4ZFQ
 

On 03/01/2022 23:22, Steve Kavanagh via groups.io wrote:
the ALC meter ends up around the middle of the "good" range or a bit above.
So at least for some modern rigs such as the the IC-7300 and FTDX10, it seems the general advice to keep the ALC at zero is not quite accurate,
Steve,

But are you sure the ALC is active?
Do your rigs do what the K3 does? People say the meter in that reads audio input level up to 4 bars. ALC starts to operate when that level is exceeded.


73 Alan G4ZFQ


Michael Black
 

There are 3 types of rigs (it's always 3, right?)
#1 Any ALC indication is attenuating your tx signal (most rigs) (e.g. IC-7610, TS-590D)#2 Some ALC indication occurs before ALC kicks in (Elecraft, IC-7300)#3 ALC indicator doesn't matter (IC-7300) -- note the 7300 is here as it covers #2 and #3 and one of the few I've seen where ALC doesn't matter -- can't generate harmonics on that rig though right now I'm unsure of linearity at other than the minimum ALC needed.
ALC by itself is not the cause -- but it is the only tool a user has unless they can see their own signal.ALC is the meter used to indicate when you are over-driving the tx chain which is kind of it's purpose in life.The problem is the ALC meters do not have units and calibration varies though it does seem there's a general behavior for a specific model.
I can tell you there's a couple of us that have been on the warpath several years now helping people clean up their harmonics.  Many end up around 90W into a 100W setting on the rig which is a very safe level with almost zero chance of harmonics.  Some end up at 100W.  And we use ALC to determine their "safe" level.  It would help if we had some people that could see their own signal -- what's not known is if all rigs and give full power without harmonics (and given Rob Sherwood's testing there are likely quite a few that can't).
Some of you may have noticed the bands are pretty clear now -- we're down to just a few operators per month now -- although I'm still wanting to go through one month without seeing harmonics from anybody.  I have high hopes for 2022 :-)
It might be useful for the community to start a list of rigs and the settings used and the desired ALC behavior to achieve max power without harmonics.
Mike W9MDB

On Tuesday, January 4, 2022, 02:43:17 AM CST, Alan G4ZFQ <alan4alan@gmail.com> wrote:

On 03/01/2022 23:22, Steve Kavanagh via groups.io wrote:
the ALC meter ends up around the middle of the "good" range or a bit above.

So at least for some modern rigs such as the the IC-7300 and FTDX10, it seems the general advice to keep the ALC at zero is not quite accurate,
Steve,

But are you sure the ALC is active?
Do your rigs do what the K3 does? People say the meter in that reads
audio input level up to 4 bars. ALC starts to operate when that level is
exceeded.


73 Alan G4ZFQ