Can I use BS170 instead of FDT86256?

[reytek79]

Hi guys, I was never able to use my Trusdx Banda Classica, as soon as I bought it, the FDT86256 burned out here in Brazil. I can't find them to buy on the internet. The cost is 45 dollars, almost the same as a complete board in China.
I would like to know if I can just replace the FDT86256 with BS170 without making other changes to the circuit?

[Karavan]

I join the question.

[s57l]

Well, as nobody answers…
Low and classic bands version obviously share 80, 40 and 20m.
https://dl2man.de/2-trusdx-assembly/
Here you can check the values of capacitors and coils in both designs, as low band uses bs170 and classic uses fdt output fet, to see the differences.
Bs170 i believe are less useful on higher bands and are much more sensitive to high swr. Also there are many many fakes around, be careful.
I am pretty sure there are people on this forum willing to send some fdt in a simple letter?
GL 73

[DL2MAN]

3xBS170 have relatively similar C as 1xFDT86256, so from a filter perspective, it can be interchanged.
But BS170 are not really fast enough for frequencies above 20m Band, so your Efficiency above 20m will perform below average.
P.S. Replacing something in the filter -and FET is part of Filter- requires re-tuning for best efficiency, before real use !
And as always: Do tuning with USB Power Supply, only when you´re above 70-80% Efficiency, connect 12V.

73 Manuel; DL2MAN

[reytek79]

Well, as nobody answers…
Low and classic bands version obviously share 80, 40 and 20m.
https://dl2man.de/2-trusdx-assembly/
Here you can check the values of capacitors and coils in both designs, as low band uses bs170 and classic uses fdt output fet, to see the differences.
Bs170 i believe are less useful on higher bands and are much more sensitive to high swr. Also there are many many fakes around, be careful.
I am pretty sure there are people on this forum willing to send some fdt in a simple letter?
GL 73

Well, my friend, it's very complicated to use the tr usdx for this reason, I burned the fet during the adjustment, and now I'm having this problem with the shipping cost, I just saw it on the mouse and on the digikey the total cost is 54 dollars for a classic band card on the China costs 40 dollars, if a friend was willing to send it by letter it would be great.

[badger_qrp]

reytek, check your messages

[reytek79]

reytek, check your messages

Friend, I checked, no new private message arrived.

[gebuwald@online.de]

Hello Foraner
In the meantime I have learnt (read here in the forum) that the BS170 can be exchanged for an FDT86256. SMD soldering points are available on the back of the board. As my little device has only just been finished, I can't say any more about it yet, I'm still waiting for the MOSFet to be delivered. Costs about €1 here in Germany, but shipping costs €20!!!
73 Gerd
DL9GAW
https://forum.dl2man.de/viewtopic.php?t=1369