[Elecraft] Power Cord Questions

[Don Wilhelm]

Elecraft did provide a fuse and a circuit breaker.  There is a 
resettable fuse in the power line for the QPR K3 (also the K2), and a 
circuit breaker with the KPA3.  That means the K3 protects itself.

That also means that the K3 cannot provide safety protection for the 
power wiring nor the supply itself, so fuses at the power supply are 
prudent things to add - even if the power supply has overvoltage and 
overcurrent protection.

73,
Don W3FPR

On 3/9/2012 11:18 PM, WILLIS COOKE wrote:
> My answers will be different from some you have seen.
> 1.  I would not use any fuses.  The RM35M has a current limiter circuit and a line fuse to protect it.  The K3 has a circuit breaker to protect it. If you are installing a transceiver in a car, you need a fuse in the positive to protect against a wire short and you need a fuse in the negative to protect you from a loose battery ground that routes your starter current through your transceiver ground.
>
> 2.  The power cord should be at least #10 and as short as reasonable.  6 feet is fine!  Much more than 10 feet and you might consider 2 #12 or #8.
>
> 3.  I would not use a fuse unless I was using a home made supply with no limiter or a battery for power.  If Elecraft thought you needed a fuse they would have given you one.
>   
> Willis 'Cookie' Cooke
> K5EWJ&  Trustee N5BPS, USS Cavalla, USS Stewart
>
>
> ________________________________
>   From: Lee Buller<k0wa at swbell.net>
> To: Elecraft Reflector<elecraft at mailman.qth.net>
> Sent: Friday, March 9, 2012 8:37 PM
> Subject: [Elecraft] Power Cord Questions
>
>
> 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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