[bars] PSA for FT8/FT4 users - HOLD TX FREQ

Mon May 5 09:21:38 CDT 2025

I'd just add that these same principles apply even when the 'sound card'
function is inside the radio and the computer is controlling it over a USB
connection.

--
73 Jim K1IR

On Mon, May 5, 2025, 10:06 Jim Idelson <jim at k1ir.com> wrote:

> The quality of your RF output signal has a lot to do with the quality of
> the audio signal driving the radio. You can create a poor quality input
> signal with too little or too much audio amplitude. Too little can cause a
> poor signal-to-noise ratio; too much can put you in a situation where the
> signal can become distorted. These problems, if present, will be also be
> present in the radio RF output signal.
>
> There is a range of audio levels over which the computer audio system
> operates wuth good SNR and low distortion. If you run below or above that
> range, your on-the-air signal can be degraded.
>
> The output control in the WSJT app only controls the computer audio level.
>
> So, the point I'm trying to make is that, while you do have some ability
> to adjust output power with that audio level, taking the power to extremes
> this way may not result in the best signal quality.
>
> The best explanatory example I can suggest is having your radio adjusted
> for 100W output, but then reducing the power to 5 watts using the WSJT
> audio control. The tiny audio signal from the computer will not be of as
> good a quality as a full-range audio output. You would get better RF output
> quality if you set the radio RF output to 5W and drive it with a clean
> full-range audio output signal from the computer.
>
> Happy digital moding!
> --
> 73 Jim K1IR
>
> On Mon, May 5, 2025, 09:25 Adam Smith via bars <bars at w1hh.org> wrote:
>
>> Chris, All -
>>
>> One thing that wasn't clear to me as a new FT-mode operator (I'm still
>> not a very regular user) was how I should control power output.  There are
>> many positions taken / methods used if you search for this online.  Since
>> you're basically using USB from the radio's perspective, the actual
>> transmitted power is controlled both by the power setting in the radio, and
>> the settings in your computer & software which create the audio input.
>>
>> The advice I've gotten most from operators I trust is - set the radio to
>> the maximum intended power level.  E.g. on a desktop rig this could be
>> 100%/100W, or say half that if you want to de-rate for digital mode duty
>> cycle.  Then use the power output slider at the lower right side of the
>> WSJTX interface to control the actual output level.  Make sure that Windows
>> (or other OS, but Windows always seems to change things when you're not
>> looking) isn't applying some other level control (there are per-interface
>> and sometimes per-program settings in the Sound control panel or whatever
>> it's called).  Watch the meters on the radio to assess your actual peak
>> output and to make sure that ALC is not reaching 100%, which will cause you
>> to splatter.
>>
>> Probably a good idea to start with low power and ramp up after you show
>> that you have the audio and control paths working.  You can also check that
>> audio is being sent by routing it to the speakers instead of to the radio
>> audio interface.
>>
>> If you come back to the setup after having things disconnected (or after
>> Windows has updated), and find that you seem to have no output, check the
>> settings on the computer side first.  Especially on Windows I find that
>> often the COM port has changed, or gotten disconnected from the digimode
>> program, or something ... or the audio/"mixer" settings have changed and
>> are sending the output to the wrong place.  Related to that - make sure
>> that you're not sending *all* sound from your computer to the rig audio
>> interface when it's plugged in - including beeps/alerts, music you're
>> playing, etc.
>>
>> Again, I'm not the most regular FT* user, but you asked for some
>> starting-point tips and those are things I've run into while dabbling with
>> FT-x, Feldhell, js8call, etc.  Glad to hear from others too.
>>
>> 73,
>> Adam / AA1N
>>
>> On Sun, May 4, 2025 at 11:14 PM Tim - K1DC via bars <bars at w1hh.org>
>> wrote:
>>
>>> Congrats, Chris!
>>>
>>> Please ping me if you have questions.
>>>
>>> Tim/K1DC
>>> On 5/4/2025 16:00, Christopher Lennon wrote:
>>>
>>> Well thanks for the encouragement all.
>>>
>>> It turns out that getting receive to work was as simple as connecting
>>> all the cables together and turning it on.  Getting it to transmit was
>>> another matter.  Hours of YouTube videos later and the settings were right
>>> and the G90 quirk that line input gain needs to be maxed out.
>>>
>>> I didn't call CW, so I didn't show up on the psk reporter, but I
>>> completed a QSO with KU4OC.
>>>
>>> Thanks!
>>> Chris
>>> W2BPL
>>>
>>> PS I had hold TXfreq checked!
>>>
>>> --
>>>
>>> Courageously sent from a non-Apple device that *includes* a headphone
>>> jack.
>>> ------------------------------
>>> <https://k1dc.com/img/k1dc-qsl-card-front.png> Tim Carter - K1DC
>>> +1.978.710.0133 <1.978.710.0133>
>>> k1dc.radio at gmail.com
>>> https://k1dc.com
>>>
>>> "Computers are incredibly fast, accurate and stupid; humans are
>>> incredibly slow, inaccurate and brilliant; together they are powerful
>>> beyond imagination." -- *Albert Einstein*
>>>
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>>
>>
>> --
>> "Be well, do good work, and keep in touch." -Garrison Keillor
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