[Elecraft] Power Cord Questions

[Eugene Balinski]

Lee, 


What size wire are you using ?   Should not be smaller than
#12. 

The length should be as short as comfortably possible.
  That means as short as possible with enough extra length
to dress the cable around the operation bench if/as needed,
and to be able to pull the radio out of its operation
position easily with out pulling the power cord out of the
radio either on purpose or by accident.   No need for any
more length. 

Also, Be sure that the connections at the power supply
terminals are solid.  I used to work summers at a power
supply house.  They made very high current regulated power
supplies for the military.  There were instances where the
customer would connect the test load to the PS with clip
leads, and when the voltage at the load was out of spec,
send it back.   

There was nothing wrong with the supply.  The clip leads
had too much resistance, and at the rated load, would drop
too much voltage because of the bad connection at the PS
terminals.   Be sure your connections to the PS are clean
and tight.

Fuses should be mounted close to the supply, just like they
are in your house.  In the event of a short, you want to
break the circuit before a fire starts. 

Present (currant?) thought says to fuse both leads.  Use
low loss auto blade type fuses.  Other fuse holders can
have a lot of resistance, and under load, drop the voltage.
  I have seen the cheap clip type de-solder a fuse cap !
 You can get the auto blade holders with red and black
leads at your local auto parts store to build your own, or
buy them from Quicksilver Radio
http://qsradio.com/index.htm  or Powewerx all made up. 

http://www.powerwerx.com/fuses-circuit-protection/atc-inline-fuse-holder-ring-terminals-10-gauge.html

73,

Gene K1NR




On Fri, 9 Mar 2012 18:37:44 -0800 (PST)
 Lee Buller <k0wa at swbell.net> wrote:
> 
> I am rebuilding the power cord from my RM35M to the K3.
> 
> Questions.....
> 
> 1.  Do you need fuses to be in both the positive and
> negative lead?  Or, since I 
> am a "fixed" station, can I get away with one fuse in the
> positive lead?  
> Currently, I have both leads fused.
> 
> 2.  What length should the power cord be....considering
> that there will be some 
> power consumption (voltage drop) in the line which is
> longer than shorter?  My 
> current length is over 6 feet.
> 
> 3.  Should the fuse(s) be mounted at the radio or at the
> power supply?  
> Currently, mine are right at the power supply.
> 
> The reason why I am rebuilding the power cord is that I
> am getting somewhat of a 
> voltage drop on key down.  According to the K3, the
> voltage is at 13.8 but goes 
> to 11 volts at key down at 100 watts....around 21 to 22
> amps.  So, I suspect 
> something might a tad glitchy in the power cord.  Maybe I
> just need to reinstall 
> the Anderson Power Poles.
> 
> Comments?
> 
> Lee - K0WA
> 
> 
> 
> 
>  In our day and age it seems that Common Sense is in
> short supply.  If you don't 
> have any Common Sense - get some Common Sense and use it.
>  If you can't find any 
> Common Sense, ask for help from somebody who has some
> Common Sense.  Is Common 
> Sense divine?
> 
> Common Sense is the image of the Creator expressing
> revealed truth in my mind. 
> -  John W. (Kansas)
> 
> Never interfere with anything that isn't bothering you.
>
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