Elecraft

KX3 fuses

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TerryB

KX3 fuses

I was looking at my power leads and realaized I had no fuses in the lines.
The factory power lead as well had no fuses. I'm about to change that with
inline fuses.

I would appreciate any comments..
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Don Wilhelm

Re: KX3 fuses

Terry,

The KX3 has internal protection, but a fused power lead (only necessary
in the positive lead) provides additional protection. That is important
IMHO when powered by an external battery - there is a lot of energy in a
battery, and if the wire is pinched and shorts, it will spew molten metal.

Fuse close to the power source, NOT the radio end of the power cable.

73,
Don W3FPR

On 10/15/2019 12:54 PM, Terry Basom wrote:

> I was looking at my power leads and realaized I had no fuses in the lines.
> The factory power lead as well had no fuses. I'm about to change that with
> inline fuses.
>
> I would appreciate any comments..
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> Elecraft mailing list
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k6dgw

Re: KX3 fuses

Well ... yes, best to fuse the + conductor. However, be aware that
inline fuse holders [and their fuses] are not zero ohm superconducting
devices. The best ones seem to be the automotive blade-type [Rig
Runners use them] with a wide contact surface and wiping action on
insertion and removal. K<mumbles> [actually, most radios] do not like
low supply voltages, it increases the IMD among other things. So after
installing the fuse, you should adjust your power supply voltage to make
sure it's not sagging under load from the additional resistance.

In the case of a mobile installation, you should fuse BOTH conductors.
Should the connection from the battery to vehicle frame become
disconnected or high resistance, starting current return will be through
your radio equipment's chassis and return conductor. I've never heard
of this actually happening but then there's a reason aircraft connectors
are made so things can't be cross connected.

I witnessed a real event where cross connection happened, however with
apologies to Pierre Fermat, the story is too long to fit in this email.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 10/15/2019 2:19 PM, Don Wilhelm wrote:

> Terry,
>
> The KX3 has internal protection, but a fused power lead (only
> necessary in the positive lead) provides additional protection. That
> is important IMHO when powered by an external battery - there is a lot
> of energy in a battery, and if the wire is pinched and shorts, it will
> spew molten metal.
>
> Fuse close to the power source, NOT the radio end of the power cable.
>
> 73,
> Don W3FPR
>
> On 10/15/2019 12:54 PM, Terry Basom wrote:
>> I was looking at my power leads and realaized I had no fuses in the
>> lines.
>> The factory power lead as well had no fuses. I'm about to change that
>> with
>> inline fuses.
>>
>> I would appreciate any comments..

Chris Parfitt

Re: KX3 fuses

In reply to this post by Don Wilhelm

I certainly agree with Don. As I try to keep a modular approach for my equipment, I use Powerpoles on everything. For portable equipment, I created short fused cables from ATC blade fuses (just got them from Walmart or an auto parts store) and some black 12-gauge wire with Powerpoles on both ends. With the Powerpoles, I can use on any cable close to the power source.

Hope this helps,
Chris, AC4MP

> On Oct 15, 2019, at 5:19 PM, Don Wilhelm <[hidden email]> wrote:
>
> Terry,
>
> The KX3 has internal protection, but a fused power lead (only necessary in the positive lead) provides additional protection. That is important IMHO when powered by an external battery - there is a lot of energy in a battery, and if the wire is pinched and shorts, it will spew molten metal.
>
> Fuse close to the power source, NOT the radio end of the power cable.
>
> 73,
> Don W3FPR
>
>> On 10/15/2019 12:54 PM, Terry Basom wrote:
>> I was looking at my power leads and realaized I had no fuses in the lines.
>> The factory power lead as well had no fuses. I'm about to change that with
>> inline fuses.
>> I would appreciate any comments..
>> ______________________________________________________________
>> 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
>> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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Don Wilhelm

Re: KX3 fuses

In reply to this post by k6dgw

All,

An additional point in mobile installations - do NOT connect the
negative directly to the battery. Follow the negative battery lead to
the point where that lead connects to the frame.

Many modern vehicles have sensing devices in that path from the battery
negative and the point where it connects to the frame. Connecting
directly to the battery bypasses those important sensors.

73,
Don W3FPR

On 10/15/2019 5:37 PM, Fred Jensen wrote:

>
> In the case of a mobile installation, you should fuse BOTH conductors.
> Should the connection from the battery to vehicle frame become
> disconnected or high resistance, starting current return will be through
> your radio equipment's chassis and return conductor. I've never heard
> of this actually happening but then there's a reason aircraft connectors
> are made so things can't be cross connected.
>
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TerryB

Re: KX3 fuses

Thanks for all the comments? Really great information. I always wondered
why Elecraft didn't include a fused power lead with their radios.. I have
the KX3... Maybe their desktop radios do come with a fused power lead...

On Tue, Oct 15, 2019 at 5:54 PM Don Wilhelm <[hidden email]> wrote:

> All,
>
> An additional point in mobile installations - do NOT connect the
> negative directly to the battery. Follow the negative battery lead to
> the point where that lead connects to the frame.
>
> Many modern vehicles have sensing devices in that path from the battery
> negative and the point where it connects to the frame. Connecting
> directly to the battery bypasses those important sensors.
>
> 73,
> Don W3FPR
>
> On 10/15/2019 5:37 PM, Fred Jensen wrote:
>
> >
> > In the case of a mobile installation, you should fuse BOTH conductors.
> > Should the connection from the battery to vehicle frame become
> > disconnected or high resistance, starting current return will be through
> > your radio equipment's chassis and return conductor. I've never heard
> > of this actually happening but then there's a reason aircraft connectors
> > are made so things can't be cross connected.
> >
> ______________________________________________________________
> 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
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