[Elecraft] K3 13.8 VDC power

[Don Wilhelm]

David,

I think the answer to your question is a matter of degree.
I do not have any specific test data on the IMD increase as the DC 
voltage is reduced, but it is a fact that the IMD with 'nominal 12 volt' 
transceivers will worsen as the voltage drops.
The fact that the K3 IMD is better than most other transceivers also 
says that the IMD as the voltage goes down is better on the K3 than others.

If you are concerned about it, I suggest you reduce the power to 
something like 75 or 80 watts when your power source voltage decreases.  
The difference between that power and 100 watts is likely not to be 
noticed by the receiving stations.

73,
Don W3FPR

On 12/22/2014 5:50 PM, david Moes wrote:
> I'm just curios  is there any real test data available showing what 
> IMD may be present at  various supply voltages?   I have heard many 
> comments on the reflector over the years saying to keep the voltage 
> high  one member saying to keep it at 15V.    The specs say 13.8 V 
> nominal during TX. (11 V min, 15 V max)       I would think that the 
> transmit signal should be fairly clean within this range.
>
> At home its on a regulated supply 13.8 so NP   but at the cottage 
> where there is no utility power  its on a battery  with 6 and 10ga 
> wiring  all using solar charge.  At night I will see voltages drop to 
> about 12V after operating with lighting from the same battery for a 
> while  usually about 1:00 am in a contest.  this is when I go off the 
> air and to bed, as this is typically about when the battery reaches a 
> 40-50% charge and I don't like to go below this.   is operating 
> approaching 12 volts (transmit) really an issue?
>