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Hi Terry, all

> For any potential buyer - it may be salvageable, particularly

> now that there is a third-party MOD kit available to replace?

> the self-destructing PA!

It will be salvageable simply by replacing the BS170s as per the standard QDX build. Furthermore?the QDX PA doesn't "self-destruct"; thousands in use have demonstrated good reliability but in the case of failure for whatever reason such as severe SWR mismatch, overload, shorts etc., BS170s are easily available and inexpensive.?

The mentioned 3rd party mod kit is not supported, recommended or condoned by QRP Labs. The FDT86256 transistor used is listed as obsolete by the manufacturer?ON. It is out of stock at Mouser and listed as obsolete, and at Digikey they have stock but it is "while stocks last". ON Semi's suggested replacement transistor is the FDT86246 but this suffers the same gate threshold mismatch and has much higher input capacitance.?

Furthermore as discussed in this topic:

the suitability is questionable; the higher capacitances likely make it less efficient particularly in the high-band QDX, and the significantly higher gate threshold voltage compared to BS170 would mean the FDT86256 isn't as well saturated which will also probably make it less efficient (more heat overall). Other than that it may have other issues which may only appear in widespread use which are not yet apparent; whereas there is considerable experience with the BS170 demonstrating reliability and durability.?

All agreed! Experimentation is always encouraged and your results were interesting.?