[5-13-03]

Okay, 


A new Q7 and Q3/4/5 will be in the mail today. It seems these Fairchild
ones work best, at least compaired to another type I got from Mouser by
mistake. 


I wish I had thought to put a pull up on that line. There's even a place to
put it, under R20. If you have a 1/8 watt resistor, you could add it there,
from the Vcc side of R20 to the short track just to it's left, looking at
the bottom of the board. Something around 10 K should do the trick. 


One of the first things the uP does is set up the port pins, which should
happen in a fraction of a micro second after the oscillator starts. But
under some conditions, that apparently is long enough to cause damage. Q7
is turned on by C45 having to charge up, so there is power going to the
finals durring that undefinded window. And of course, the driving gate is
being clocked by noise since the DDS hasn't started up yet. 


At least that's what I think is happening. Seab had this problem happen to
his rig and hasn't happened again since I had him disconnect the antenna on
power up, knock on wood, hi. One intereseting charicteristic of this Class
E amp is it the fets don't draw any significant current if there is no load
connected to the output. 


Anyway, I hope this doesn't turn into a wide spread problem! But I'm glad
now the lady at Digi-Key talked me into buying a 100 of those BCP69's! And
I'm going to look for some that are more rugged for next time, if there is
one :-)


72,
Steve, KD1JV
"Melt Solder"
White Mountains of New Hampshire
http://www.qsl.net/kd1jv/