Finished my build and really love the receive on this radio! For such a small device to be able to do so many things on a usb power connector is amazing! The cw decoder works surprisingly well.
Anyway, power out on the device on USB power is showing a swr of around 2.8 with 10 watts out on most bands on my Classic Bands build. This is into a dummy load. Actual power measured out is around .8v or .08watts using the dummy load/volt meter (qrpguys dummy load/power meter plugged in for measuring).
I expected a power out of up to .5w and swr of very low, so I suspect I might have issues with wiring of t1 or t2 or both. Voltage at either side of l15 is 4.8v (using USB power).
I attached some pics of the transformers, but the pics could have been focused a little better...
If the pics aren't too clear, here is how it is wired:
T1 - 1:7 - the 1 loop goes straight through the 7 turn goes to the angled connections
T2 3:21 - the 3 loop goes through the angled connections on the pcb, the 21 loop goes through the straight through (this seems wrong maybe?)
Again, getting good receive, but almost no power out leaves me wondering what coil isn't done right, or connected right. The two transformers are inline for receive so if they weren't connected with a good solder joint I would expect no receive.
The poor readings with lots of power suggests a backwards transformer maybe? The lack of power out on all bands, not really sure here, maybe I somehow killed the output transistor.
T2 is 3 turns through 21 on the angled one!
T1 and T2 must be wound same direction.
Crossing fingers this helps and you haven't shot your PA-FET FTD86256 on the backside.
Check always with USB powered at the beginning, about 0.3W and 0.5W if you are lucky and adjusted the toroids.
73 de Chris
Please use thinner soldering wire the next time. You can much better control the amount with it.
It seems like the primaries are both wound counter clockwise. It is kind of hard to tell. Also, the 3 turn is wound in the same direction as the 21t on t2.
The t2 transformer seems to be inserted right (with the 3t on the angled solder pads).
T1 has the single turn going on the straight solder pads and the 7 turn on the angled. Is this backwards?
So, got hold of a working board and was able to closely look at my transformers vs the working transformers on the working board. It is quite hard to see where the windings actually go.
My issue was solved when I swapped the two connections on T2 that are nearest to T1. Phase was the same as the working board so no issues on mine for that characteristic. I am now getting power out on every band with varying efficiency which is another issue for me to troubleshoot.
Great little radio! Still have a lot to learn. Efficiency on my build at 5v usb power ranges from 35% to 68%, so will dig into that next. Looking at the case that I got with the working radio, I really like it so have to wrangle up a case for mine as well. Didn't think it would be as compact and nice of a case so time to dust off my 3d printer or maybe visit the local library where they print items. Also, the working radio has processor board issues where USB is not detected when attached to a PC to work through, so I will build an I2C interface there and figure out how to update/reload or whatever might be needed on that front.