FT8 Transmission Level

Juan TG9AJR

Hello, I have a Flex 6600. What is the ideal or optimal transmission LEVEL when transmitting on FT8 ?

I notice there is a LEVEL meter on the right hand side of SmartSDR and just above COMPRESSION, that goes from -40dB (Left) to 0 (Right in red), and when I transmit I get a full color line and at the end of this line to the right I small square marker in the same color of the color line.

Some one told me in -10 in yellow/green color and the solid square in between -10 and 0.

Scott Russell - N1SER

KY6LA_Howard

dlwarnberg

Jaun.... FYI... am listening for you now. 

dlwarnberg

Howard, been out of the digital game some time but 100 watts?  Last I played I rarely exceed 10 watts, then again that was JT65... if FT8 all that much different?

dlwarnberg

Clarification, listening for you now on 20 meters, FT8

Neal Pollack, N6YFM

Juan TG9AJR

OK thank you Howard.

And if I may ask what is the proper way to adjust that LEVEL ?
Using the DAX TX Gain and/or the Adjust TX Audio Level (PWR) the vertical slide on JTDX/WSJT-X ?

KY6LA_Howard

FT8 is a WEAK SIGNAL MODE NOT A LOW POWER MODE.

That said use only the power your need to use to make the contact.


if the other station is weak.. say -22 or less then it is likely you will need to use power for him to hear you


ALSO... with Flex DAX your decoding is entirely in the Digital Chain vs external boxes such as Rigblaster that do A/D and D/A conversions.. so it is likely you will have a 3-6 dB gain advantage over the other guy..  This means that if you are hearing him at say-18 then it is likely given equivalent antennas and power that you are being heard at -18-6=-24  - hence you need power for him to overcome his equipment deficiencies so that he can hear you.

KY6LA_Howard

I use DAX TX gain to control levels

DH2ID

Very good advice! I have a very clear signal using the same settings, measured
with my spectrum analyzer and harmonic distortion measurement.

Patrick

Another way of getting proper audio level is to set the Xmt. Level in the wsjt-x app at no more then 80 % then set DAX to run as high as possible without going into the red on the peaks on the audio drive level . As you move from band to band check the level and adjust audio drive as needed. The radio will remember that level on a band by band basis.

Neal Pollack, N6YFM

Juan:    YES :-)

Adjusting any of;

+ DAX TX level slider
+ WSJT-X Power Slider
+ Windows Playback Device Levels Tab

will all affect this SSDR Flex TX level.
For personal preferrence and no real scientific reason, I tend to
make sure that the windows level tab slider is not set above 80%,
and also that the WSJT-X power slider is set around/approx 80%,
then I use the DAX TX level slider to do the final level adjustment.
This is one of more than a dozen ways to properly adjust the level.
Whatever you choose, just don't let the peaks go over the 0 dB level
on the Flex SSDR or Maestro interface.

Cheers,

Neal

Ned K1NJ

   Weak signal modes are used to -hear and decode- weak signals, not
necessarily to transmit them.  For example:  EME, moonbounce, might
best use a "weak signal mode", but it still would take considerable power
from your antenna to make the trip.
                                 Ned,  K1NJ

Juan TG9AJR

Thank You all I really appreciate all the feedback, 73.

Dwayne_AB6A

Just a follow up to this question, given the radio is rated 25W max in AM and FM modes and digital modes have similar duty cycles, does that confirm max power in digital modes should be 25W regardless?

Neal Pollack, N6YFM

Dwayne_AB6A

Neal Pollack, N6YFM

Full ICAS duty cycle has no meaning. Someone left the cage door open in Marketing again. But in general, two piece amps with a larger power supply can go key down for longer periods of time.

Dwayne_AB6A

Tim N9PUZ