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K3 on JT-65, ALC varies widely

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Dave Hachadorian-2

K3 on JT-65, ALC varies widely

I just started playing with JT-65 and JT-9 this weekend, and I’ve already worked a bunch of DX, so it’s basically working ok.

Transmitting on JT-65, I see a lot of variation in ALC and power as the various tones change. I’m using Data A mode with the stock 2.7 filter. I just had a QSO with tone frequencies of about 1800 – 1950 Hz, and ALC varied from zero to five bars on the different tones. Sound card output is about 50%, and Line In level is at 12. Is this variation normal, or am I doing something wrong, and where should I set the ALC?

Thanks.

Dave Hachadorian, K6LL
Yuma, Arizona

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Jim Brown-10

Re: K3 on JT-65, ALC varies widely

Hi Dave,

What you're seeing is fairly normal for your setup. The 2.7 kHz 5-pole
filter is not as flat as the 2.8 kHz 7-pole filter, which I noticed on
RTTY. I subsequently switched to 7-pole filters (but not in the Sub-RX).
A JT65 signal is about 220 Hz wide, so when you get near the top of the
audio bandpass, you also run into the slope of that filter. As with all
other data modes transmitted by audio, 4-5 bars flashing is optimum.

There's another trick that the latest WSJT-X plays to minimize audio
harmonics that result from overdriving in the audio chain. If you allow
WSJT-X to do so, they will automatically put you in split mode, with an
offset that puts the second harmonic outside the passband of the TX filter.

My recommendations for setting audio levels is here. it follows the
discussion of USB interfaces. http://k9yc.com/USB_Interfaces.pdf The
reason I recommend setting computer sound cards 6-10 dB below audio clip
is that their percent distortion often rises by 10 dB in that last 6 dB
of output level. On a vintage Thinkpad, I measured -30 dB second
harmonic relative to fundamental just below clip and and -40 dB below
fundamental with the output reduced by 6 dB.

One update to my "rule of thumb" about whether you need a better
interface is that, thanks to decoding improvements in the latest version
of WSJT-X, you should occasionally see good decodes in the range of -26
to -28 for JT65. And a caution -- while second pass decoding often finds
a second station on nearly the same frequency as one decoded on the
first pass, roughly 5% of the time a second pass decode may be bogus.

73, Jim K9YC

On Sun,4/16/2017 2:29 PM, Dave Hachadorian wrote:
> Transmitting on JT-65, I see a lot of variation in ALC and power as the various tones change. I’m using Data A mode with the stock 2.7 filter. I just had a QSO with tone frequencies of about 1800 – 1950 Hz, and ALC varied from zero to five bars on the different tones. Sound card output is about 50%, and Line In level is at 12. Is this variation normal, or am I doing something wrong, and where should I set the ALC?

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Joe Subich, W4TV-4

Re: K3 on JT-65, ALC varies widely

In reply to this post by Dave Hachadorian-2

Since bars 0-4 represent audio drive level and *not* true ALC when
in digital mode (DATA A, AFSK A), what you are seeing represents a
significant change in *audio drive level* for the different tones.

Are you sure you are using DATA A and not AFSK A with the AFSK
Filter turned on? What frequency range are the tones?

73,

... Joe, W4TV

On 4/16/2017 5:29 PM, Dave Hachadorian wrote:

> I just started playing with JT-65 and JT-9 this weekend, and I’ve already worked a bunch of DX, so it’s basically working ok.
>
> Transmitting on JT-65, I see a lot of variation in ALC and power as the various tones change. I’m using Data A mode with the stock 2.7 filter. I just had a QSO with tone frequencies of about 1800 – 1950 Hz, and ALC varied from zero to five bars on the different tones. Sound card output is about 50%, and Line In level is at 12. Is this variation normal, or am I doing something wrong, and where should I set the ALC?
>
> Thanks.
>
> Dave Hachadorian, K6LL
> Yuma, Arizona
>
>
>
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Robie Elms-2

Re: K3 on JT-65, ALC varies widely

I also see the same behavior as Dave. I have verified my K3 is in DATA A
and the TX Equalization is a flat line. However, I routinely make
contacts with JT65. I use WSJT-x v 1.7.0

Robie - AJ4F

On Mon, Apr 17, 2017 at 12:10 AM, Walter Underwood <[hidden email]>
wrote:

> TX EQ could cause problems like this if not in DATA A.
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>
> > On Apr 16, 2017, at 4:52 PM, Joe Subich, W4TV <[hidden email]> wrote:
> >
> >
> > Since bars 0-4 represent audio drive level and *not* true ALC when
> > in digital mode (DATA A, AFSK A), what you are seeing represents a
> significant change in *audio drive level* for the different tones.
> >
> > Are you sure you are using DATA A and not AFSK A with the AFSK
> > Filter turned on? What frequency range are the tones?
> >
> > 73,
> >
> > ... Joe, W4TV
> >
> >
> > On 4/16/2017 5:29 PM, Dave Hachadorian wrote:
> >> I just started playing with JT-65 and JT-9 this weekend, and I’ve
> already worked a bunch of DX, so it’s basically working ok.
> >>
> >> Transmitting on JT-65, I see a lot of variation in ALC and power as the
> various tones change. I’m using Data A mode with the stock 2.7 filter. I
> just had a QSO with tone frequencies of about 1800 – 1950 Hz, and ALC
> varied from zero to five bars on the different tones. Sound card output is
> about 50%, and Line In level is at 12. Is this variation normal, or am I
> doing something wrong, and where should I set the ALC?
> >>
> >> Thanks.
> >>
> >> Dave Hachadorian, K6LL
> >> Yuma, Arizona
> >>
> >>
> >>
> >> ______________________________________________________________
> >> Elecraft mailing list
> >> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >> Help: http://mailman.qth.net/mmfaq.htm
> >> Post: mailto:[hidden email]
> >>
> >> This list hosted by: http://www.qsl.net
> >> Please help support this email list: http://www.qsl.net/donate.html
> >> Message delivered to [hidden email]
> >>
> > ______________________________________________________________
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> > Post: mailto:[hidden email]
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Brian Hunt

Re: K3 on JT-65, ALC varies widely

In reply to this post by Dave Hachadorian-2

Don't see a problem with making minor adjustments of the Line In gain during the first transmission. When I adjust the level using the WSJT TUNE button I usually see the wild fluctuations mentioned. A small "tweak" to the gain will set right.

73,
Brian, K0DTJ
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Joe Subich, W4TV-4

Re: K3 on JT-65, ALC varies widely

In reply to this post by Robie Elms-2

TX ad RX EQ are forced to flat in DATA A (and AFSK A) mode.

What frequency tones (TX #### Hz in WSJT-X) are you using? Is WSJT-X
in split mode?

If I adjust the audio input *carefully* to 4 bars, I will see the "ALC"
vary from 3 to 5 bars and the power output will vary between 98 and 102
Watts (when set for 100 W). With the audio input adjusted to "4 bars
with the 5th flickering", I see marginally tighter power control - 99
to 102 W. However, in no case is there a significant variation in the
power output.

The *only time* power output is not as expected is if I am not using
split mode and trying to transmit with audio tones below 300 Hz or
above 2500 Hz (outside the DSP bandwidth).

73,

... Joe, W4TV

On 4/16/2017 8:15 PM, Robie Elms wrote:

> I also see the same behavior as Dave. I have verified my K3 is in DATA A
> and the TX Equalization is a flat line. However, I routinely make
> contacts with JT65. I use WSJT-x v 1.7.0
>
> Robie - AJ4F
>
> On Mon, Apr 17, 2017 at 12:10 AM, Walter Underwood <[hidden email]>
> wrote:
>
>> TX EQ could cause problems like this if not in DATA A.
>>
>> wunder
>> K6WRU
>> Walter Underwood
>> CM87wj
>> http://observer.wunderwood.org/ (my blog)
>>
>>> On Apr 16, 2017, at 4:52 PM, Joe Subich, W4TV <[hidden email]> wrote:
>>>
>>>
>>> Since bars 0-4 represent audio drive level and *not* true ALC when
>>> in digital mode (DATA A, AFSK A), what you are seeing represents a
>> significant change in *audio drive level* for the different tones.
>>>
>>> Are you sure you are using DATA A and not AFSK A with the AFSK
>>> Filter turned on? What frequency range are the tones?
>>>
>>> 73,
>>>
>>> ... Joe, W4TV
>>>
>>>
>>> On 4/16/2017 5:29 PM, Dave Hachadorian wrote:
>>>> I just started playing with JT-65 and JT-9 this weekend, and I’ve
>> already worked a bunch of DX, so it’s basically working ok.
>>>>
>>>> Transmitting on JT-65, I see a lot of variation in ALC and power as the
>> various tones change. I’m using Data A mode with the stock 2.7 filter. I
>> just had a QSO with tone frequencies of about 1800 – 1950 Hz, and ALC
>> varied from zero to five bars on the different tones. Sound card output is
>> about 50%, and Line In level is at 12. Is this variation normal, or am I
>> doing something wrong, and where should I set the ALC?
>>>>
>>>> Thanks.
>>>>
>>>> Dave Hachadorian, K6LL
>>>> Yuma, Arizona
>>>>
>>>>
>>>>
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email]
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to [hidden email]
>>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
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>>
> ______________________________________________________________
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Robie Elms-2

Re: K3 on JT-65, ALC varies widely

Joe,

I'll comment on my setup:

1. Lock TX=RX is checked

2. tones are approximately 1500 hz

Robie - AJ4F

On Mon, Apr 17, 2017 at 1:34 AM, Joe Subich, W4TV <[hidden email]> wrote:

>
> TX ad RX EQ are forced to flat in DATA A (and AFSK A) mode.
>
> What frequency tones (TX #### Hz in WSJT-X) are you using? Is WSJT-X
> in split mode?
>
> If I adjust the audio input *carefully* to 4 bars, I will see the "ALC"
> vary from 3 to 5 bars and the power output will vary between 98 and 102
> Watts (when set for 100 W). With the audio input adjusted to "4 bars
> with the 5th flickering", I see marginally tighter power control - 99
> to 102 W. However, in no case is there a significant variation in the
> power output.
>
> The *only time* power output is not as expected is if I am not using
> split mode and trying to transmit with audio tones below 300 Hz or
> above 2500 Hz (outside the DSP bandwidth).
>
> 73,
>
> ... Joe, W4TV
>
>
>
> On 4/16/2017 8:15 PM, Robie Elms wrote:
>
>> I also see the same behavior as Dave. I have verified my K3 is in DATA A
>> and the TX Equalization is a flat line. However, I routinely make
>> contacts with JT65. I use WSJT-x v 1.7.0
>>
>> Robie - AJ4F
>>
>> On Mon, Apr 17, 2017 at 12:10 AM, Walter Underwood <[hidden email]
>> >
>> wrote:
>>
>> TX EQ could cause problems like this if not in DATA A.
>>>
>>> wunder
>>> K6WRU
>>> Walter Underwood
>>> CM87wj
>>> http://observer.wunderwood.org/ (my blog)
>>>
>>> On Apr 16, 2017, at 4:52 PM, Joe Subich, W4TV <[hidden email]> wrote:
>>>>
>>>>
>>>> Since bars 0-4 represent audio drive level and *not* true ALC when
>>>> in digital mode (DATA A, AFSK A), what you are seeing represents a
>>>>
>>> significant change in *audio drive level* for the different tones.
>>>
>>>>
>>>> Are you sure you are using DATA A and not AFSK A with the AFSK
>>>> Filter turned on? What frequency range are the tones?
>>>>
>>>> 73,
>>>>
>>>> ... Joe, W4TV
>>>>
>>>>
>>>> On 4/16/2017 5:29 PM, Dave Hachadorian wrote:
>>>>
>>>>> I just started playing with JT-65 and JT-9 this weekend, and I’ve
>>>>>
>>>> already worked a bunch of DX, so it’s basically working ok.
>>>
>>>>
>>>>> Transmitting on JT-65, I see a lot of variation in ALC and power as the
>>>>>
>>>> various tones change. I’m using Data A mode with the stock 2.7
>>> filter. I
>>> just had a QSO with tone frequencies of about 1800 – 1950 Hz, and ALC
>>> varied from zero to five bars on the different tones. Sound card output
>>> is
>>> about 50%, and Line In level is at 12. Is this variation normal, or am I
>>> doing something wrong, and where should I set the ALC?
>>>
>>>>
>>>>> Thanks.
>>>>>
>>>>> Dave Hachadorian, K6LL
>>>>> Yuma, Arizona
>>>>>
>>>>>
>>>>>
>>>>> ______________________________________________________________
>>>>> Elecraft mailing list
>>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>>> Post: mailto:[hidden email]
>>>>>
>>>>> This list hosted by: http://www.qsl.net
>>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>>> Message delivered to [hidden email]
>>>>>
>>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email]
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to [hidden email]
>>>>
>>>
>>> ______________________________________________________________
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>>> ______________________________________________________________
>> Elecraft mailing list
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Brian Hunt

Re: K3 on JT-65, ALC varies widely

In reply to this post by Brian Hunt

Oops, that should have been Line OUT gain.
Brian, K0DTJ

On 4/16/2017 18:19, Brian Hunt wrote:

> Don't see a problem with making minor adjustments of the Line In gain during the first transmission. When I adjust the level using the WSJT TUNE button I usually see the wild fluctuations mentioned. A small "tweak" to the gain will set right.
>
> 73,
> Brian, K0DTJ
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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Don Wilhelm

Re: K3 on JT-65, ALC varies widely

In reply to this post by Brian Hunt

Brian,

Try this -- set the K3 LINE in gain to somewhere near mid-range, and
then adjust the soundcard "speaker" slider to give you close to the 4
ALC bars with the 5th bar flashing. Refine that level with slight
adjustments to the LINE in gain.

You can use TX TEST while making those adjustments which will not
transmit any RF.

Adjust the desired power output with the power knob.

If you do not achieve the required number of ALC bars, the K3 will
"power hunt" causing significant fluctuations in the output power.

There seems to be a greater number of questions about this "problem" for
users of "JT" software than for other soundcard data modes. I don't
know why because the "JT" software should be no different than any other
soundcard data mode. Perhaps the user is trying to follow the
recommendations in the JT mode instructions (I have not looked at them),
but typically data mode instructions are for non-Elecraft tranceivers
and say that the user should set the power to maximum and use the
soundcard audio to adjust the power level. That does not work with
Elecraft gear which controls power differently than other amateur
transceivers. For Elecraft transceivers, adjust the audio level as
specified and adjust the desired power with the power knob. I cannot
stress this fact enough.

73,
Don W3FPR

On 4/16/2017 9:19 PM, Brian Hunt wrote:
> Don't see a problem with making minor adjustments of the Line In gain during the first transmission. When I adjust the level using the WSJT TUNE button I usually see the wild fluctuations mentioned. A small "tweak" to the gain will set right.
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Dave Hachadorian-2

Re: K3 on JT-65, ALC varies widely

I am working on this some more this morning.

I set the LINE IN gain to 30 (midrange). The speaker output is set to 90%, but there is an amplitude slider in WSJT-X, and I adjusted that to 5 bars of ALC in WSJT Tune mode (constant 1100 Hz tone in this case). The K3 is definitely in DATA A mode.

Then I called CQ, and the ALC meter and power output were all over the place from 0 - 5 on ALC, and 10 Watts to 70 Watts on power output. On an external analog wattmeter, I could see the power ramping up on some of the longer duration tones.

So then I took an oscilloscope and measured the audio voltage coming out of the sound card, and found that each tone has a different voltage level coming out of the sound card! The audio level varies all over the place as the CQ goes on. JT-65 is supposed to be constant amplitude tones of 65 different frequencies, so something is not working right, either in the WSJT-X program or in my computer. I will look into that some more. It is not a K3 problem.

I am using WSJT-X v. 1.7.0 r7405. The sound card is an old Soundblaster Live that works just fine for transmitting WAV and live microphone on SSB.

Anyway, I am making QSO’s, some of them with signal strength as low as –25 dB. I don’t think I am long for this mode anyway. Life is too short for 1 Baud communication.

Dave Hachadorian, K6LL
Yuma, Arizona

-----Original Message-----
From: Don Wilhelm
Sent: Sunday, April 16, 2017 7:41 PM
To: Brian Hunt ; Reflector Elecraft
Subject: Re: [Elecraft] K3 on JT-65, ALC varies widely

Brian,

Try this -- set the K3 LINE in gain to somewhere near mid-range, and
then adjust the soundcard "speaker" slider to give you close to the 4
ALC bars with the 5th bar flashing. Refine that level with slight
adjustments to the LINE in gain.

You can use TX TEST while making those adjustments which will not
transmit any RF.

Adjust the desired power output with the power knob.

If you do not achieve the required number of ALC bars, the K3 will
"power hunt" causing significant fluctuations in the output power.

There seems to be a greater number of questions about this "problem" for
users of "JT" software than for other soundcard data modes. I don't
know why because the "JT" software should be no different than any other
soundcard data mode. Perhaps the user is trying to follow the
recommendations in the JT mode instructions (I have not looked at them),
but typically data mode instructions are for non-Elecraft tranceivers
and say that the user should set the power to maximum and use the
soundcard audio to adjust the power level. That does not work with
Elecraft gear which controls power differently than other amateur
transceivers. For Elecraft transceivers, adjust the audio level as
specified and adjust the desired power with the power knob. I cannot
stress this fact enough.

73,
Don W3FPR

On 4/16/2017 9:19 PM, Brian Hunt wrote:
> Don't see a problem with making minor adjustments of the Line In gain during the first transmission. When I adjust the level using the WSJT TUNE button I usually see the wild fluctuations mentioned. A small "tweak" to the gain will set right.
______________________________________________________________
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Joe Subich, W4TV-4

Re: K3 on JT-65, ALC varies widely

> I set the LINE IN gain to 30 (midrange).

This is generally too high - I run between 10 and 15.

> The speaker output is set to 90%,

Are you running the "bare" speaker output to the Line In or
do you have a 10:1 (20 dB) attenuator between the speaker
output and the Line Input?

> but there is an amplitude slider in WSJT-X, and I adjusted that to 5
> bars of ALC in WSJT Tune mode (constant 1100 Hz tone in this case).

This is the *WORST PLACE* to adjust the level. Set the WSJT-X slider
to max and make an attenuator with a 10K resistor from the speaker out
to the top of a 1 K pot and connect the wiper of the port to Line IN.
Adjust drive with the pot.

> On an external analog wattmeter, I could see the power ramping up on
> some of the longer duration tones.

This is a symptom of insufficient audio drive and/or failure to
properly perform Transmitter Gain CAL (in the K3 Utility).

> So then I took an oscilloscope and measured the audio voltage coming
> out of the sound card, and found that each tone has a different
> voltage level coming out of the sound card! The audio level varies
> all over the place as the CQ goes on.

Contact the WJTS-X development team - their list is:
[hidden email]

73,

... Joe, W4TV

On 4/17/2017 1:43 PM, Dave Hachadorian wrote:

> I am working on this some more this morning.
>
> I set the LINE IN gain to 30 (midrange). The speaker output is set
> to 90%, but there is an amplitude slider in WSJT-X, and I adjusted
> that to 5 bars of ALC in WSJT Tune mode (constant 1100 Hz tone in
> this case). The K3 is definitely in DATA A mode.
>
> Then I called CQ, and the ALC meter and power output were all over
> the place from 0 - 5 on ALC, and 10 Watts to 70 Watts on power
> output. On an external analog wattmeter, I could see the power
> ramping up on some of the longer duration tones.
>
> So then I took an oscilloscope and measured the audio voltage coming
> out of the sound card, and found that each tone has a different
> voltage level coming out of the sound card! The audio level varies
> all over the place as the CQ goes on. JT-65 is supposed to be
> constant amplitude tones of 65 different frequencies, so something is
> not working right, either in the WSJT-X program or in my computer. I
> will look into that some more. It is not a K3 problem.
>
> I am using WSJT-X v. 1.7.0 r7405. The sound card is an old
> Soundblaster Live that works just fine for transmitting WAV and live
> microphone on SSB.
>
> Anyway, I am making QSO’s, some of them with signal strength as low
> as –25 dB. I don’t think I am long for this mode anyway. Life is
> too short for 1 Baud communication.
>
> Dave Hachadorian, K6LL Yuma, Arizona
>
>
>
>
>
>
>
> -----Original Message----- From: Don Wilhelm Sent: Sunday, April 16,
> 2017 7:41 PM To: Brian Hunt ; Reflector Elecraft Subject: Re:
> [Elecraft] K3 on JT-65, ALC varies widely
>
> Brian,
>
> Try this -- set the K3 LINE in gain to somewhere near mid-range, and
> then adjust the soundcard "speaker" slider to give you close to the
> 4 ALC bars with the 5th bar flashing. Refine that level with slight
> adjustments to the LINE in gain.
>
> You can use TX TEST while making those adjustments which will not
> transmit any RF.
>
> Adjust the desired power output with the power knob.
>
> If you do not achieve the required number of ALC bars, the K3 will
> "power hunt" causing significant fluctuations in the output power.
>
> There seems to be a greater number of questions about this "problem"
> for users of "JT" software than for other soundcard data modes. I
> don't know why because the "JT" software should be no different than
> any other soundcard data mode. Perhaps the user is trying to follow
> the recommendations in the JT mode instructions (I have not looked at
> them), but typically data mode instructions are for non-Elecraft
> tranceivers and say that the user should set the power to maximum and
> use the soundcard audio to adjust the power level. That does not
> work with Elecraft gear which controls power differently than other
> amateur transceivers. For Elecraft transceivers, adjust the audio
> level as specified and adjust the desired power with the power knob.
> I cannot stress this fact enough.
>
> 73, Don W3FPR
>
> On 4/16/2017 9:19 PM, Brian Hunt wrote:
>> Don't see a problem with making minor adjustments of the Line In
>> gain during the first transmission. When I adjust the level using
>> the WSJT TUNE button I usually see the wild fluctuations mentioned.
>> A small "tweak" to the gain will set right.
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