[Elecraft] P3 Issue

[Michael Carter]

Ken,

I have not experienced the difficulty
with my P3 that you encountered,
but the fact that both the P3 front
panel display and the external SVGA
display shut down indicates a problem
with data not being provided to either
display driver system OR there is a
thermal problem with one of the
onboard voltage regulators on the P3
Rear Panel I/O board.  The P3 has
both +5V and + 3.3V regulators with
crowbar over-voltage protection, and
both are fed from the +12V DC input
jack.  The P3 SVGA board has additional
voltage regulators supplying 1.2, 2.5, and
3.3V, and these are fed from the +5 V
regulated supply on the P3 Rear Panel I/O
board.

My suspicion is a thermal sensitivity
in the +5 V regulator or its crowbar
protection circuit.  However, I would
first check the +12V DC input connection
to the P3 and be sure that it is stable
at +12V over time.  If you supply that
voltage from the auxiliary +12V output
of a K3 or K3s, you should also check
that the problem doesn't stem from
a problem inside the transceiver.  My
recollection is that a modification
was required in the original K3 to
increase the available current at the
auxiliary +12V DC output to support
the SVGA option in the P3.

I am curious to know what you find.......

73,
Mike, K8CN