Replacing and matching blown BC170 FETs

[Websurfman]

When blown BS170 FETs have to be replaced due to e.g. combination of high power supply voltage (above some 12V) and poor antenna swr (happened to me two times), it is important to replace them with FET characteristics matching closely to each other.
The parallel configuration will result in unequally devided power handling/heating of the FETs if not matched !
For testcircuit see below.

To make the transmitter power stage more robust against poor swr, I glued the FETs together on a small heatsink.
Flatten the top of the FETs with e.g. sanding paper and glue them with 3 sec. super glue onto a small piece of heatsink.
When fixed, add quite some more glue and spread immediately some baking soda powder on the still wet glue making it instantly solid, shake off the surplus powder and repeat these steps until FETs are glued mechanically and thermally solid to the heatsink.

73 de PA0HSP

Test BC170.jpg (67.03 KiB) Viewed 1088 times

3xBS170 heatsink.jpg (32.45 KiB) Viewed 1088 times

Heatsink.jpg (48.24 KiB) Viewed 1088 times

[Ohwenzelph]

Is “39E” 2.49 MΩ / 1%, in words: two point four nine Megaohms with one percent tolerance?

[Websurfman]

39E is 39 Ohm, tolerance 5% is OK

[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?

[K3RTA]

I wonder if there would be a problem taping a few of these to a letter, and sending them in a regular envelope? If you want to try that, I'll order a few of these and send them to you. You can repay the kindness to someone else in the hobby where you are.

72,

K3RTA

[reytek79]

I wonder if there would be a problem taping a few of these to a letter, and sending them in a regular envelope? If you want to try that, I'll order a few of these and send them to you. You can repay the kindness to someone else in the hobby where you are.

72,

K3RTA

Friend, it would be very good, but I don't know if this is possible or how it could be done, here in Brazil I once sent a pendrive, I put it between several sheets, I folded it and put it in a letter envelope. How would the values be transferred?