[Elecraft] K3/P3/Quadra

[Tom Hammond]

Hi Larry:

>I have a question about hooking up the P3 to the K3 12vdc out.
>
>I'm using a cable of your design and it's been really great.
>
>I'm using that output for the 12vdc sense voltage to turn the Quadra 
>on and off.
>
>My P3 will be here Monday.
>
>It seems to me the that cable they supply is made to connect to the 
>12vdc out on the K3.

And it is.

>Will there be a problem if I put a "Y" connector on the 12vdc out 
>and fed both the P3 and the "sensor" 12vdc and the P3.

It Depends... I 'think' the Quadra PROBABLY only requires a 
'knowledge' that there's 12VDC on that port in order to turn itself 
on... e.g. it's not being 'powered' in an manner from the K3, just 
being 'told' that "yes, I'm turned on", so virtually no CURRENT is 
being require from the K3 "+12VDC" output.  To confirm this, I'd 
insert a mA meter and check to see how much (if any) current is being 
supplied TO the Quadra.  If there's a significant amount of current, 
then a "Y" connector may not be appropriate.

The P3 Owner's Manual specifications state that the P3 requires "10 
to 15 VDC @0.5A" which, if accurate, pretty well consumes the 'rated' 
0.5A output from the K3's +12VDC @ .5A output.

HOWEVER... if the Quadra only requires a 'knowledge' that there's 
+12VDC at the port, and really doesn't require much current (if any), 
then yes, I'd think that you could probably get by with a "Y" cable 
to control the Quadra and to POWER the P3 as well.

If it turns out that the Quadra AND the P3 (together) do REQUIRE more 
current than the K3 "+12VDC" port can (or should be asked to) supply, 
then I'd probably suggest that you consider using the L3's "+12VDC" 
port to drive a small relay (or possibly a  MOSFET) which would 
switch on/off the output from a small external 12VDC power supply 
which could supply maybe 1A or so output.  Shouldn't me much 
difficulty to do this if it comes to that point.

Hope this helps.

73,

Tom Hammond   N0SS



>Or should I make a longer cable and feed the P3 separately?
>
>Thanks in advance for any information you can provide.
>de <mailto:k2gn at k2gn.com>K2GN - Larry - http://k2gn.com
>K3 S/N - 3278    P3 S/N - soon
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