[Elecraft] K3 beta firmware revision 3.14 now available

[wayne burdick]

Hi Paul,

Just plugging in a mono plug by itself is not detectable in firmware. 
The protection kicks in as a result of a brief spike in AF amp current 
drain. To observe this you need a mono plug, SPKRS=2, and moderate to 
high volume setting with a strong signal in the passband. This will 
eventually cause the AF amp chip to draw 1/2 to 1 amp of current on 
peaks, which firmware can easily spot.

I wouldn't suggest forcing this condition intentionally. We tested it 
on several K3s, and we know it works. But it is intended as a safety 
feature, not as a substitute for using a stereo speaker plug when SPKRS 
is set to 2.

73,
Wayne
N6KR

On May 21, 2009, at 7:54 AM, pd0psb wrote:

>
> Anybody else tested this?
> I can't get speaker protection to work.
> Or does it only work with higher AF levels?
>
> 73'
> Paul
> PD0PSB
>
>
> MCU 3.14 / DSP 2.16  May 9, 2009
>
> * SPEAKER PROTECTION: If you’re set up for stereo speakers
> (CONFIG:SPKRS = 2), but insert a mono speaker plug, the right
> speaker output will be shorted to ground. This can cause excess
> current drain if you turn volume up to high levels. The K3 now
> detects this condition, automatically turning off the right
> channel (and briefly flashing "SPRKS=1"). (It would be better,
> of course, to use a stereo plug if you set SPKRS to 2, rather
> than wait for the firmware to detect the mono plug.)


---

http://www.elecraft.com