Alternative, very comprehensive Schematic, drawn by KD4SGE & WA4ITD:
Here are the Results of the Harmonic measurements:
The TRX was un-tweaked, and built completely according to the Schematic Values of Capacitors and Toroids. Harmonic suppression is better than -43dB on ALL Bands.
UPDATE: 16. March 2022:
Alternative Bands Setups
We´ve got many user requests for alternative Band Setup. Personally we´re not really interested in that and lack the time to double- and triple check all the Information, but we wanted to give you -the user- the possibility to play around with it. Since (tr)uSDX is supposed to be a standardized rig, we cannot allow for totally custom Band Selection, but we´ve prepared 3 Options in Firmware for you:
|Lo (current Standard)||20m||30m||40m||60m||80m|
|Hi (Only Hi Bands)||10m||12m||15m||17m||20m|
|Classic (Classical Bands w/o WARC)||10m||15m||20m||40m||80m|
UPDATE 08. May 2022:
Here are my Results with “Classic Bands” Setup, using the FDT 86256 FET: (Again UPDATED 20 May 2022)
Because of higher gate threshold value, this FET requires higher PA BIAS Max Setting of 160 for best performance. With PA Bias Max 160 it was possible to get at or above 80% up to 10m Band, even with Red Toroids.
I was using the Toroids and PCB provided by our official Supplier Sunny.
The below Tables represent UNTESTED Component Values ! Use them with caution at your own Risk. The Values need to be tweaked for 5W@12V and Efficienct over 80%. Please report back in the forum about the Values that actually made it happen for you.
ATTENTION: This Table are THEORETICAL Values for 1x FDT86256 (Install ONLY Q5 as PA FET)
ATTENTION: This Table are THEORETICAL Values for 3x BS170 (Install ONLY Q1,Q2 and Q3 as PA FET)
Depending on your Setup, you only need to place the desired Component-Values to the Right Band-Slots together with the FET you want to use and Activate it in Firmware.
X Stands for Band slot (e.G. 1 for K1 -> so this would be then C10//C11)
“//” means: Those 2 are in Parallel. Putting Capacitors in Parallel is a simple Addition of Capacitance
CX0//CX1 for FDT86256 and 80m is supposed to be 1041pF
So we need to find 2 (available) Capacitor-Values, that will result in a total Capacitance closest to 1041pF as possible.
470pF//560pF would be close = 1030pF
620pF//430pF would be close = 1050pF
680pF//360pF -> BINGO = 1040pF
but a lot of other combinations are possible. Just use what you can get or have available and try to get as close as possible.
There might also be cases where you can achieve it with just one Cap. In this case place it to one of the 2 available Cap-Footprints and leave the other one empty.
Remember: (tr)uSDX Filter Capacitors ALWAYS need to be C0G/NP0 Types, rated for at least 100V !
Use some online or offline tool, to calculate the amount of Windings for your Toroids. I like this one: https://www.dl0hst.de/mini-ringkern-rechner.htm#en
Depending on Frequency you can use either T37-2 (Red) or T37-6 (Yellow) Toroids.
Happy tuning !