[Elecraft] KPA100 voltage measurements AGAIN

[Gerhard Schwanz]

Hi there,

since my last thread has gone wild ;-) ... here comes a new one.

I just checked the PCB again for any visual problems
but didn't find any. And then I did the measurements again.

I now have -0.1 to -0.15V on J3+ (yes, MINUS). Still zero V at TP1.

Any idea how this voltage could get there? I don't dare to neglect this
reading and proceed with the building...

Using a 4.7k resistance I shorted J3+ to ground and almost immediately the
voltage rises to 0V. Taking it away results in a slow drop to abt -0.1V. It
looks like discharging/charging a capacitor.

Kind regards

>>>> Old message follows...

=20
Good morning,

I'm still in the process of building my kpa100. After
my learning process concerning soldering :-) I
stumbled upon some voltages.

I'm on page 43 in the manual now and got some numbers
a bit off the given values (PS is 14V).

D13 154V
U4 -27.4V
TP1 0V
J3+ 0.1V

Are these numbers ok? Especially the last two?

Another thing. The fan at this stage is a bit out of
control. Calibrating tPA helps, but the K2 seems to
not remember this setting. Also strange is that while
setting tPA a relay can be heard switching. But maybe
this is normal at this point in the process?

Kind regards and keep on building...

Gerhard
DH3FAW



Gerhard Schwanz
DH3FAW
mailto:gerhardschwanz at yahoo.de
http://www.gs-personal.de