P3 - powering from the K3 aux plug

[Glen, W6GJB]

Guys,
I run a number of accessories from the switched power on the back of the K3.
 I run it to a powerpole strip and then just plug in all the items that I
want to power up with the rig.  So far I run a W2, an LP-PAN and a 6m
pre-amp.  I'd like at add the P3.  The K3 plug says 0.5A max, which is what
the P3 draws.  So it looks like its either/or.  Is there
enough conservatism in the rating of that power socket to add the P3?

Thanks,
Glen, W6GJB
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[KK7P]

  The short answer is no.

73,

Lyle KK7P

> ...The K3 plug says 0.5A max, which is what
> the P3 draws.  So it looks like its either/or.  Is there
> enough conservatism in the rating of that power socket to add the P3?

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[Iain MacDonnell - N6ML-2]

On Wed, Aug 18, 2010 at 9:01 PM, GLEN BROWN <[hidden email]> wrote:
> Guys,
> I run a number of accessories from the switched power on the back of the K3.
>  I run it to a powerpole strip and then just plug in all the items that I
> want to power up with the rig.  So far I run a W2, an LP-PAN and a 6m
> pre-amp.  I'd like at add the P3.  The K3 plug says 0.5A max, which is what
> the P3 draws.  So it looks like its either/or.  Is there
> enough conservatism in the rating of that power socket to add the P3?

Put a suitably-rated relay between your power supply and the powerpole
strip, and power the relay from the accessory output on the K3.

    ~Iain / N6ML
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[Bruce Beford-2]

Glenn,
That output is fused internally at 600 mA, and is supplied via a 1n4007
diode (1 amp max). Best not to exceed the 500 mA recommended max load. An
option would be to supply power to your powerpole strip from the same supply
that feeds the K3, but have it switched by a small relay controlled by the
Aux DC out of the K3.
 
GL, Bruce N1RX
 
> Guys,
> I run a number of accessories from the switched power on the back of the
K3.
> I run it to a powerpole strip and then just plug in all the items that I
> want to power up with the rig.  So far I run a W2, an LP-PAN and a 6m
> pre-amp.  I'd like at add the P3.  The K3 plug says 0.5A max, which is
what
> the P3 draws.  So it looks like its either/or.  Is there
> enough conservatism in the rating of that power socket to add the P3?
 
> Thanks,
> Glen, W6GJB

 

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[Alan Bloom]

On Wed, 2010-08-18 at 14:16 -0700, Lyle Johnson wrote:
> The short answer is no.

The long answer :=) is that the P3 uses a pair of DC-DC converters to
convert +12V down to the +3.3V and +5V needed by its circuitry.  This
tends to make the input "constant power" meaning that current times
volts is nearly constant.  With a 14V supply, the P3's current is well
under 500 mA.  But with 11V input, the current is close to that value.

The best solution is probably what a couple others suggested:  Use the
K3's switched "12V DC OUT" jack to power a relay which switches the
power to all the other devices.  Then you don't have to worry about it.

Alan N1AL

> 73,
>
> Lyle KK7P
>
> > ...The K3 plug says 0.5A max, which is what
> > the P3 draws.  So it looks like its either/or.  Is there
> > enough conservatism in the rating of that power socket to add the P3?
>
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>
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