[Elecraft] K3 Current Drain When Off

[Ron D'Eau Claire]

I disconnected everything from my K3 except the power cable and the drain
when off remains at 38mA. 

I don't have the time right now to pull the PA module, but that sounds like
the next best possible culprit. 

I had never noticed the parasitic drain because my station power supply is
switched off when I leave the shack. 

73, Ron AC7AC



-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Wayne Burdick
Sent: Wednesday, October 16, 2013 1:34 PM
To: jim at audiosystemsgroup.com
Cc: Reflector Elecraft
Subject: Re: [Elecraft] K3 Current Drain When Off

Jim,

Here's one possible explanation:

The external power supply must drop all the way to zero V, as must any all
K3 I/O signals. This may have implications for attached equipment.

If there's any residual voltage on the supply or I/O lines, even 1 V, the K3
may not turn off all the way. It turns out that the brown-out detection
circuitry on microcontrollers can be confused at some power levels that are
low enough to look like a brownout but not high enough to properly power the
detection circuitry. Under such conditions the MCU may continue to run on
power-down via the on/off switch, resulting in the radio drawing an
unpredictable amount of current.

If residual supply or I/O leakage isn't the cause, then I suspect a problem
with your K3's on/off circuitry or possibly even the PA module. (You could
test the latter theory by unplugging the KPA3.) Every K3 we've tested drops
to a very small number of milliamps of current drain when off.

73,
Wayne
N6KR

 
Jim Brown <jim at audiosystemsgroup.com> wrote:

> Nope. I measured both units several times, and just now repeated the
measurements.
> 
> 73, Jim
> 
> On 10/16/2013 11:23 AM, Eric Swartz - WA6HHQ, Elecraft wrote:
>> Hi Jim - you must be misreading the meter by several decimal points :-)
>> 
>> We just measured several K3s in the lab and they both draw less than 5 mA
when off.
>> 
>> Eric
>> elecraft.com



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