Spurious TX harmonics at FT8 on JTDX...

Gerry

What cause these spurious TX harmonics on FT8 and its possible solutions?

I monitor FT8 frequently on 20m and the Flex looks great with spots overlayed on the pan adapter... I installed SliceMaster to handle all the settings for JTDX to function. Works very well!



The problem arises when I try to reply to a CQ... The Flex panadapter now looks like this and WHOA!



Where are these harmonics coming from?

I manage to complete the QSO, though. But TX with these birdies, I felt, was not good. How to eliminate these? It happens each time I TX, when I reply to a CQ or when I CQ myself.

It may be interesting to note that, when I TUNE using the Flex TX radio controls, I get this beautiful, crisp signal (we kinda expect this)... centered on the FT8 20m frequency.



BUT when I TUNE from the JTDX program (right-hand side of program screen with other Tabs - Monitor, Bypass, etc) I get this -



All the harmonics appear! JTDX must be the culprit...

I have not found any JTDX setting to fix. I have made sure the Working Frequencies enumerated in the Files >> Settings>>Frequencies contain ONLY the FT8 frequency (deleting/taking away other frequencies added for F/H mode in the band). At TX the harmonics appear.

I suppose this is the same for the other FT8 bands on JTDX...

Any suggestions?

73s
Gerry
DU7EYG 

KD0RC

David Decoons, wo2x

Gerry

Andy M5ZAP

KD0RC

YES!  I love it when a plan comes together!  My Flex is about as old as yours.  I don't know how I lived all these years without a panadpter...
Len

Al K0VM

MENARD PHILIPPE

J'ai mon DAX a -10 db et pourtant j'ai des harmoniques à l'émission .
Test fait en mode FDX sur deuxième VFO

David Decoons, wo2x

I find with WSJT-X I leave the power slider in WSJT-X up all the way and set DAX TX to 48. This keeps the peak indicator just below zero (yellow).

Dave wo2x

David Decoons, wo2x

@MENARD PHILIPPE

Désolé je ne parle pas français. J'utilise Google Traduction.
J'ai mon DAX TX réglé au niveau 48. Puissance WSJT-X au maximum.

Quelle est la hauteur des éperons par rapport au signal de transmission réel ?