Re: Nouveau 75 Errata


nm0s_qrp <ai9e_qrp@...>
 
Edited

Regarding the observed Q11, Q10 heating, in normal operation these will exhibit no heating at all in the receive mode.
 
What I suspect has happened is that Q11 and Q12 had shorted together with power applied, and damaged some components on the board, resulting in the heating observed.
 
Notice that Q11 and Q12 are close together on the board.  This is why the assembly instructions explicitly specify that the heat sink mounting screws are to be installed through the back of the heat sink, emerging through the tab of the transistor.  This limits the opportunity for the two transistors to come in electrical contact.
 
So to reiterate, the hardware stackup should be screw, passing through flat washer, back of heat sink, black heat sink pad, back of transistor, lock washer, and nut.
 
The three legs on the heat sink should be snipped off.
 
Before soldering the transistor to the board, check the spacing between the heat sink and the board to make certain that the sink does not contact any of the surface mount components on the board.  Readjust the sink on the transistor if necessary.  Only then should you solder the transistor down.
 
Finally, be certain that there is no contact between Q11 and Q12 before power up.
 
That should prevent any of damage to components due to heat sink shorting.
 
73 Dave NM0S

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