[Elecraft] Small got-ya to watch for when doing the K3 12VDC Out Current Mod

[Adrian]

Thankyou Alan, I guess for those like the OP and probably myself, that don’t like to get into the insides without a good reason;

Running the K3 at 15v (HD pwr cable too) works out great esp with all the other benefits, hence my observation to those hesitant to do the mod.

Adrian ... vk4tux

-----Original Message-----
From: Alan Bloom [mailto:n1al at sonic.net] 
Sent: Monday, 10 September 2012 3:58 PM
To: vk4tux
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Small got-ya to watch for when doing the K3 12VDC Out Current Mod

On Sun, 2012-09-09 at 20:50 -0700, vk4tux wrote:
> Ok, I was thinking the P3/SVGA drew less current at 15v than 12v, due 
> to the
> 5/3.3/2.5/2.2 v pwr supply setup requiring less current at 15v input 
> than it does at 14v input or less.

That's right.

> I checked the K3 output with a 20 ohm/50w variable rheostat and it 
> trips at 0.6amp or 600mA on my fluke 87.

With a 15V supply, the P3 current is probably low enough that it will run OK from the DC output jack of an unmodified K3.  The modification is still worthwhile (1) so that the P3 will still work if you (or someone
else) tries to run it on a lower-voltage supply, and (2) because the modification reduces the voltage drop to the DC output jack.

Alan N1AL


> 
> 
> 
> 
> 
> 
> What most people notice is that the P3 will switch off after a period 
> of operation when the resettable fuse finally heats enough to open. 
> Your K3 may have a defective resettable fuse in the 12V output line.
> 
> 
> 
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