Tr usdx classic band no mod ssb

[Ea1fof]

Good afternoon

my trusdx burned the fdt86256 and after replacing a mosfet in its place, now I only have modulation in fm and am, but in ssb it does not modulate, in ssb it generates a noise that covers the modulation, the question is: is it a chinese mosfet of poor quality or burn something from the ssb in the chip mega? thanks a regards... I'm thinking of buying a new motherboard, since I don't have the ability to change the mega

[Ea1fof]

Gracias
Thank you

[dl6sez]

Hello OM,

if you got fm and cw output of your (tr)uSDX than everything must be ok!
SSB only sends power out to antenna when you talk into your microphone
If you think somethink in software is not correct now,
you can do a soft reset by pressing tuning knob while connecting to power.

73 de Chris

[dl6sez]

...and if you check with a receiver nearby you always get a bad coupling and bad sound in ssb.
Check your signal on a WebSDR, have a look at http://kiwisdr.com/public/
or Websdr.org

73 de Chris

[Ea1fof]

Thank you for your response, the ssb mod was checked with another radio 10km away, the partner only received noise,Even though I don't speak into the microphone, he always receives noise, he did not receive modulation, however on fm and am he did receive mod, then if he tells me that the fm mod works, mega it will be OK?

the partial reset was done and nothing changed

[dl6sez]

Hello OM,

yes it must do!
There is no additional hardware doing ssb modulation other than your microphone signal going directly into the Atmega328
If FM works also SSB must work!
Look at the menue point tx drive maybe you changed it, but if FM works with modulation....
You can reprogram your firmware if you want via USB, but we never heard from such an effect.

73 de Chris

[Ea1fof]

thank you very much, that was what I wanted to know, if there was something different between the fm and the ssb, then I guess the problem will be the false fdt86256... I'll try to change the mosfet... thank you very much for your help... If when changing the mosfet keeps failing.. i'll try to reprogram it. thank you very much

[Ea1fof]

After 3 mosfets and some adjustment in the toroids, the mosfets stopped burning, but the ssb kept failing, it sent a carrier without speaking to the microphone, reflashed with the beta version and it has come back to life, great...it needs to give some tweaks to powers and efficiencies... but the important thing is that it works again

[Ea1fof]

5 mosfets later, something must be wrong with this classic band board... with 5v efficiencies of 70-80 in the 80m and 40m band, everything is fine there, both with 5v and 12v, but in the 20m bands at 10m... the efficiencies are lousy, less than 50 and with 5v it holds, but when connecting the 12v it burns the fet... what a disappointment, some components must not be the correct ones. fewer turns but the thing remains the same, it only works on 80m and 40m

[dl6sez]

Hello OM,

maybe you are right, but have you measured and aligned first the harmonic notch as DL2MAN
showed in his videos?
I know that classic version with single FET is much more sensitive to misaligned toroid windings especially on higher bands. Do you have red cores for the lower bands and yellow ones for the higher bands?
Don't mess up than with older Kit having only red cores T37-2 .... There will be a very bad match for the FET on higher bands than (due to yellow T37-6 used there).
And yes depending on what you adjust at TX noise gate you will get a carrier at ssb, can be adjusted up to 100% carrier with TX noise gate! Remember (tr)uSDX is doing PWM on carrier.... see:
viewtopic.php?t=813

mixed toroids classic band:
https://dl2man.de/wp-content/uploads/20 ... _86256.pdf

73 de Chris

[Ea1fof]

correct, aligned the second harmonic with nanovna following in the steps of Dl2man, the high band toroids are yellow, the radio works with 5v on all bands, but when I put 12v on it, it only works on 80m and 40m, as soon as I transmit on any of the high bands burn the MOSFET

[DL2MAN]

Did you select the right board in the menu ?

73 Manuel DL2MAN

[Ea1fof]

Yes, the classic band is selected, another of the problems is that without an rf card, when the ptt has been pressed for a long time, it also turns off... this equipment went wrong... I'll try a LO band kit because I like the concept pocket radio.. I hope the new kit doesn't turn out as bad

[K1IMD]

I too am having trouble with my "classic" RF deck. I chose a frequency on each band that is the low end of the phone band to optimize the radio which I used to tune the 2nd harmonic filter. I used a (3) 18650 battery pack at about 12.1 volts to power the radio while testing. I used my service monitor to tweak the harmonic filters with no problem. However, checking each band to prepare tweaking each output, starting at 80m when I get to 20m the single FET fails (3 times now). I have checked for solder splashes or something else obvious but have found nothing. I have reflowed the torrid connections to ensure there was a good connection. The "classic" board is selected in the menu.

The "low" RF deck radio I have seems OK although the efficiencies are a bit lower expected.

Seems others are having some similar issues and on the same band!

73
K1IMD

[Ea1fof]

In the end, I installed 3 bs170 on the classic board, 75% efficiency in 80m and 40m and 70% in the 20m, 15m and 10m band, efficiency below 60... with one less turn on the efficiency toroids in all the bands, powers between 6w and 3w, but the board works like this... it doesn't burn the mosfets using 12v