New build - 13v 9.9 SWR - Messed up T1 T2 soldering?

[Stein LA7NDA]

Hi.

I thought everything was going honky dory, until the first time I tried to transmit. Then I displayed 13v and 9.9 SWR. So after reading up on the forum I assumed I have a bad solder or winding on T1 or T2. I quickly found out it is impossible to check with a multimeter, since all ends of the transformer toroid's are grounded as seen by a DC multimeter. I have now taken off T2, rewound it ( 7:1 instead of the initial 21:3 for simplicity) and re soldered it. Same problem. I then took of T1. My solder pads are starting to look pretty bad now so I am slowly loosing hope of a working unit.

I am trying to understand the routing on the PCP for the T1 primary. One end goes to antenna center pin but for me it looks like the other side just goes to a pad that is not connected to anything. That can't be correct?

Is there any other possible culprit for the high power & SWR other than T1, T2?

Any guidance would be appreciated.

[dl6sez]

Hello OM,

yes there is a problem with the windings, maybe enameled wire not really contacted at the solder joint (possibly also a wrong direction of windings).
And: Please why do you use 13V if you don't know what's wrong and maybe kill something? Use lower voltage 5V USB is enough to see if all, yes all works correct.
The one possible reason for your (tr)uSDX behaviour....T1 and or T2

73 de Chris

[Stein LA7NDA]

Ok. Thanks. I will test with USB power from now on. I really did not know anything was wrong when I powered it with 13v for the first transmit...

Any Idea where the "other" end of T1 primary goes? According to the schematics:
ANT_OUT - T1 Primary - ANT. From what I can see on the PCB and the RF_ibom: It goes from Antenna center pin - T1 primary - isolated solder pad. Am I missing something?

[Stein LA7NDA]

(possibly also a wrong direction of windings).

Oh! Is there a right direction and a wrong direction to wind them? Mine are wound CCW.

[dl6sez]

Hello OM,

as i said it is T1 and or T2...
Have you ever heard about 4-layer pcbs?
Sorry, but simply have a look at DL2MAN's videos on his youtube channel, everything explained and done!
Think about how many 100s (tr)uSDX are already built and work,
you do not have to invent the wheel again

73 de Chris