[Elecraft] K3 power sequencing

[wayne burdick]

The preferred way to turn off the K3 is via the POWER switch. Or, from 
a computer, by sending a "PS0" command, then waiting at least half a 
second later dropping the /POWER_ON line.

You can turn the rig off at the power supply if that is unavoidable. 
Just as with a "brownout," when the firmware senses a supply voltage 
dip to 9.5 V or lower, it shuts down everything as cleanly as possible. 
But it may not have time to update all changed parameters in EEPROM 
(current VFO frequencies, etc.). Thus when you turn power back on, you 
might find the VFO in the last location you were at when you switched 
to the current band.

I once tried turning my K3 off with at power supply several dozen times 
to see if I could make anything bad happen. Nothing did. That said, do 
use the preferred method if you can.

73,
Wayne
N6KR

On Jun 7, 2009, at 11:03 AM, Geoffrey Mackenzie-Kennedy wrote:

> Joe,
>
> Many thanks for your help.
>
> I had been toying with the idea of buying a K3 for use at another QTH, 
> but
> there the mains supply is not 100% reliable. If bad things can happen 
> if the
> 13.8V supply shuts down as the result of a mains outage, that is 
> serious.
>
> 73,
> Geoff
> GM4ESD
>
>
> Joe Planisky wrote on Sunday, June 07, 2009 5:45 PM
>
>> From the owners manual (page 44 in rev D2):
>>
>> "Remote Power On/Off
>>
>> A remote-control system can pull the POWER ON line to ground (ACC
>> connector, pg. 18) to turn the K3 ON.  To turn it OFF, the controller
>> must send the K3 a "PS0;" remote-control command via the RS232  
>> interface,
>> then deactivate the POWER ON signal.  This sequence ensures  that
>> nonvolatile memory is updated correctly before shut-down."
>>
>> Note that it doesn't say how long it takes to update the NVRAM after  
>> the
>> above process is completed.  In other words, how soon after  
>> deactivating
>> the POWER ON signal can I shut down the 13.8V supply?
>>
>> 73
>> --
>> Joe KB8AP
>>
>>
>> On Jun 7, 2009, at 9:10 AM, Geoffrey Mackenzie-Kennedy wrote:
>>
>>>
>>> Is there any interface available on the K3 which would allow an  
>>> external
>>> automatic protective shutdown system to meet this requirement,  
>>> rather
>>> than
>>> having to press the POWER button by hand?
>
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