[Elecraft] K3 has internal noise with high compression settings

[Donehrlich at q.com]

Don,

My first reaction is that compression of 35 is way too high.  I never go 
over 15 or so because of all of the background noise in the shack that 
is picked up by the mic at high compression settings.  Something of that 
sort is perhaps what you are hearing .. maybe a fan or other hum-like 
sound in the local environment.  High compression makes the system super 
sensitive to low level sounds.

Don K7FJ


On 1/12/2012 9:58 AM, goldtr8 at charter.net wrote:
> Gents,
>
> Last night I disconnected all the antennas and started to look at basics
> within the shack because of my antenna problem, I decided that I should
> check the basics with my dummy load and found an interesting thing
> happening inside my K3.
>
> What I found is that when directly connected to a dummy load and I run
> the k3 at full power 110 watts, as I dial up the compression above 35 on
> the settings , I hear a hum inside the K3 and it shows RF out power in
> SSB when I am not speaking into the microphone.  Basically key up the
> mike in a quite environment in SSB mode and it goes into TX where there
> is output.
>
> I made a coax choke with snap on ferrites between the dummy load and the
> K3 to see if I could kill it but it made no difference.  Also power
> settings below 110 did make some difference and mike gain had little to
> no effect.  This happens on all frequencies, does not matter if on 160m
> or 10m.
>
> I then connected the amp between the K3 and dummy load and this noise
> starts at about a compression setting of 30 to 33.  This is with a drive
> power of 40 watts into an SGC powercube, and when the humming started
> there was TX power on my meter.
>
> The internal noise sounds like a ferrite vibrating.
>
> Other items, power is supplied via 12v batteries using a floated battery
> charger, existing antennas were disconnected from the system.
>
> Is this something that others have seen or should I call Elecraft
> support.  I am hoping I don't also have a K3 problem.
>
> Thanks
> Don
>
>
> ~73
> Don
> KD8NNU
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