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Need a Fuse on the K3's Power Line?

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Paul Grigorieff

Need a Fuse on the K3's Power Line?

I was just looking at my new K3's (#7489) power cable, and see that it is not protected by a fuse (although I think I saw an instruction to use an in-line fuse if I connect it to battery power).

I see what looks like a 20a fuse (or breaker) on the back of my K3/100, although I believe I read that it draws 25a continuous duty.

I was thinking of connecting my radio either directly to a 70a Astron p.s. (which will also handle my 50w 2m mobile rig and a variety of other smaller loads) or through a 25a fused receptacle on a RigRunner, itself connected to the Astron.

To fuse or not to fuse--that is the question, and what is peoples' experience with the RigRunner?

-Paul Grigorieff, N1HEL

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Michael Eberle

Re: Need a Fuse on the K3's Power Line?

Yes, that is a circuit breaker on the K3 so a fuse probably is not
necessary. Of course there would certainly be nothing wrong with using
a fuse.

Mike
KI0HA

On 6/13/2013 7:46 PM, PGrig wrote:

> I was just looking at my new K3's (#7489) power cable, and see that it is not protected by a fuse (although I think I saw an instruction to use an in-line fuse if I connect it to battery power).
>
> I see what looks like a 20a fuse (or breaker) on the back of my K3/100, although I believe I read that it draws 25a continuous duty.
>
> I was thinking of connecting my radio either directly to a 70a Astron p.s. (which will also handle my 50w 2m mobile rig and a variety of other smaller loads) or through a 25a fused receptacle on a RigRunner, itself connected to the Astron.
>
> To fuse or not to fuse--that is the question, and what is peoples' experience with the RigRunner?
>
> -Paul Grigorieff, N1HEL
>
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Iain MacDonnell - N6ML-2

Re: Need a Fuse on the K3's Power Line?

I believe that the circuit breaker only protects the KPA3.

If you're running off battery, or other unprotected power-source, I
think you would really want an external fuse (as close to the power
source as possible, in case you get a short in the supply cable
somehow).

73,

~iain / N6ML

On Thu, Jun 13, 2013 at 6:06 PM, Michael Eberle <[hidden email]> wrote:

> Yes, that is a circuit breaker on the K3 so a fuse probably is not
> necessary. Of course there would certainly be nothing wrong with using a
> fuse.
>
> Mike
> KI0HA
>
>
> On 6/13/2013 7:46 PM, PGrig wrote:
>>
>> I was just looking at my new K3's (#7489) power cable, and see that it is
>> not protected by a fuse (although I think I saw an instruction to use an
>> in-line fuse if I connect it to battery power).
>>
>> I see what looks like a 20a fuse (or breaker) on the back of my K3/100,
>> although I believe I read that it draws 25a continuous duty.
>>
>> I was thinking of connecting my radio either directly to a 70a Astron p.s.
>> (which will also handle my 50w 2m mobile rig and a variety of other smaller
>> loads) or through a 25a fused receptacle on a RigRunner, itself connected to
>> the Astron.
>>
>> To fuse or not to fuse--that is the question, and what is peoples'
>> experience with the RigRunner?
>>
>> -Paul Grigorieff, N1HEL
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>
> ______________________________________________________________
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Don Wilhelm-4

Re: Need a Fuse on the K3's Power Line?

In reply to this post by Paul Grigorieff

Paul,

An in-line fuse close to the power source is always a good safety
precaution.
You are protecting the wire against a fault as well as the equipment on
the far end of that wire.
A 12 gauge wire will safely handle 25 amps - but it will not safely
handle the full 70 amp output of your wower supply without vaporizing
and possibly spewing molten copper all over your hamshack, and can
present a fire possibility.

#10 wire can safely handle 40 amps, but again, not the full output of
your 70 am supply.

I encourage you to fuse near the power supply for the wire size that you
use for connections from that supply.

The rigrunner is a nice device allowing you to fuse the input for the
wire size that you have connected to the supply and also fuse the branch
circuits according to the needs of the devices being powered.

I fuse #12 wire at 25 amps and #16 at 10 amps. #18 gets a 5 amp fuse.

73,
Don W3FPR

Fuse it according to the wire size.

On 6/13/2013 8:46 PM, PGrig wrote:
> I was just looking at my new K3's (#7489) power cable, and see that it is not protected by a fuse (although I think I saw an instruction to use an in-line fuse if I connect it to battery power).
>
> I see what looks like a 20a fuse (or breaker) on the back of my K3/100, although I believe I read that it draws 25a continuous duty.
>
> I was thinking of connecting my radio either directly to a 70a Astron p.s. (which will also handle my 50w 2m mobile rig and a variety of other smaller loads) or through a 25a fused receptacle on a RigRunner, itself connected to the Astron.
>
> To fuse or not to fuse--that is the question, and what is peoples' experience with the RigRunner?
>
>

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Fred Smith-2

Re: Need a Fuse on the K3's Power Line?

In reply to this post by Paul Grigorieff

Hi Paul

I use 2 70 amp Astron's the one running my K3's and KX3 is a VS model set to
14.4 volts. It is attached to a Low Loss PWR Gate which charges 2 Optima
batteries using the power supply. If a power outage occurs it automatically
switches to battery power you never know when it happens.

The battery is fused then the PWR Gate runs to the Rig Runner where the
radios are powered. The fuses that you have should be good for one thing you
never transmit on 2 radios at the same time anyway. Well most don't unless
you're

73,
Fred/N0AZZ
K3 Ser #'s 6730/5299--KX3 # 2573--K2/100--KAT100
P3/SVGA--KPA500--KAT500--W2

running digital modes on one radio and another for CW/SSB.

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of PGrig
Sent: Thursday, June 13, 2013 7:46 PM
To: [hidden email]
Subject: [Elecraft] Need a Fuse on the K3's Power Line?

I was just looking at my new K3's (#7489) power cable, and see that it is
not protected by a fuse (although I think I saw an instruction to use an
in-line fuse if I connect it to battery power).

I see what looks like a 20a fuse (or breaker) on the back of my K3/100,
although I believe I read that it draws 25a continuous duty.

I was thinking of connecting my radio either directly to a 70a Astron p.s.
(which will also handle my 50w 2m mobile rig and a variety of other smaller
loads) or through a 25a fused receptacle on a RigRunner, itself connected to
the Astron.

To fuse or not to fuse--that is the question, and what is peoples'
experience with the RigRunner?

-Paul Grigorieff, N1HEL

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OH9VD

Re: Need a Fuse on the K3's Power Line?

In reply to this post by Paul Grigorieff

You definetly need a fuse in 12V DC line.
The reverse polarity protection does not work without the fuses.
Here is a picture what might happen without the fuses if you mess the
polarity and your power supply is stiff enough (like car battery).
http://500px.com/photo/37567226

73 de OH9VD/Jarmo
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Olli Tuppurainen

Re: Need a Fuse on the K3's Power Line?

Seems that the final fuse is PCB foil :(

Small saving but severe damage ..

Olli
OH6CT

> -----Alkuperäinen viesti-----
> Lähettäjä: [hidden email] [mailto:elecraft-
> [hidden email]] Puolesta Jarmo Blomster
> Lähetetty: 14. kesäkuuta 2013 19:16
> Vastaanottaja: [hidden email]
> Aihe: Re: [Elecraft] Need a Fuse on the K3's Power Line?
>
> You definetly need a fuse in 12V DC line.
> The reverse polarity protection does not work without the fuses.
> Here is a picture what might happen without the fuses if you mess the
> polarity and your power supply is stiff enough (like car battery).
> http://500px.com/photo/37567226
>
> 73 de OH9VD/Jarmo
> __________________________________________________________
> ____
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Edward R Cole

Re: Need a Fuse on the K3's Power Line?

In reply to this post by Paul Grigorieff

Like Ron, I do not have a fuse on the power line to my K3/10. I
guess the 6A fuse is internal with the K3 (have never replaced it).

I do supply my whole station with 14.2vdc from an Astron R50M via
12-feet of No. 6 welding wire which has a 30A BUSS Fuse at the main
distribution point on the back of the radio cabinet (under heavy load
the voltage runs at 13.8 at this point). Power splits off to several
barrier strips for connection to various equipment. The high current
(high power) loads are directly connected to the main strip at the
main fuse to reduce line loss. Many of my equipment are individually
fused. The R50M output is fused at the PS.

I have blown the 30A fuse only a couple times (over many years use)
by accidental shorts on the 12v system (but usually a momentary short
does not draw sufficient current to blow the big BUSS fuse). I do
not recall the Astron fuse ever blowing.

73, Ed - KL7UW
http://www.kl7uw.com
[hidden email]
"Kits made by KL7UW"

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