[Elecraft] K3 voltage under load

[Grant Youngman]

Maybe there's too much concern to do all the hand wringing?

It all depends on what's between the PS and the radio.  In my case,  
for example,  my 13.8v supply feeds a West Mountain Radio battery  
charger (200AH of battery), and there's a drop there (.4V).  then to a  
WMR distribution box and on to the radio.  I have 13.5v no load and  
12.5v transmit at 100W.  All of the wiring is #10 as short as  
possible.  The APP's are 45A and are properly terminated.  And the  
radio just keeps on chugging.

I've chosen not to be concerned about it.  I  may try to increase the  
RS-70M output to as close to 15v as I can, but my motivation is  
lacking to open up the box and try to adjust the unreachable output  
adjust since nothing is broken.

Grant/NQ5T


On Jun 2, 2009, at 4:41 PM, Ed K1EP wrote:

> At 6/2/2009 05:09 PM, Hector Padron wrote:
>> Certainly there is mot enough evidence to blame the PS yet,he will
>> have to read the drop at the PS output poles to see  if is the same
>> or worse,otherwise its losses at his DC cable or something lose in
>> the DC line at the K3,even a cold solder can create that,but if the
>> radio makes 100W all the time,why to worry?
>
> There are a number of reasons to worry.  If there is a defective
> connection, it could (and will) heat up and melt (or self destruct),
> causing other problems.  I have seen the plastic on power poles melt
> due to incorrect installation and high  resistance.   Typically, the
> voltage to the PA is not regulated, in the sense that it uses the
> voltage supplied to the radio which it assumes is regulated.  It does
> that because there is no room to supply a 20A regulator in the
> radio.  (if you want that, you will be buying a bigger and more
> expensive radio)  But if the voltage becomes modulated with the audio
> or other parameters, you will introduce RF distortion and other
> unwanted byproducts.  Not a good thing either.