PA transistor Heatsinking of a uBITX #ubitx


Peter LB0K
 

I can see the insulation argument to why these are installed hanging on to the IRF510s but this puts a large mechanical load on the transistor legs and increases the risks of damage, especially if one tried to use the uBITX as a portable, even as a SOTA rig.

 

One could fit a larger common heatsink that was fixed to the chassis/casing or PCB and one would then have to include rectangular insulating washers between the transistors and the heatsink.
These changes would increase the parallel drain(s) capacitance to ground, etc. etc.

 

I envisage these positive results:-

-       better mechanical strength

-       a more robust construction

-       easier to provide controlled cooling of the heatsink.

 

 

What sort of negative results should/could one expect from these measures?

 And how to fix'em?

 I envisage these negative results:-

-       a slight increase of weight

 

 

 

 Peter

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