K3 power supply fuses

[kk4oyj]

My K3 is powered from a car battery as I am always /P. I have installed fast-blow fuses rated at 25 A in each of the supply lines.

Operating at 80W RTTY this afternoon, I noted that I was getting a low voltage warning before I would have expected it. On examining the power cable, I found the fuse holders to be warm to the touch. I expect that is what was causing the voltage drop.

However, may I ask what specific (make , model) of fuse holders are you using to protect your k3?

73
John, KK4OYJ


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[J]

You might closely examine the type of connections inside the holders.  Some
aftermarket automotive fuse holders have poorly crimped connections and
might pass a quick resistance check, but....

73,
Jay
W6CJ

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of John,
9H5G
Sent: Monday, March 16, 2015 13:12
To: <[hidden email]>
Subject: [Elecraft] K3 power supply fuses

My K3 is powered from a car battery as I am always /P. I have installed
fast-blow fuses rated at 25 A in each of the supply lines.

Operating at 80W RTTY this afternoon, I noted that I was getting a low
voltage warning before I would have expected it. On examining the power
cable, I found the fuse holders to be warm to the touch. I expect that is
what was causing the voltage drop.

However, may I ask what specific (make , model) of fuse holders are you
using to protect your k3?

73
John, KK4OYJ


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[Matt Zilmer-3]

Hi John,

The KX3's KXPA100 amplifier's power cable has two inline fuses in
waterproof enclosures, one for each of the supply cables.  They take
standard automotive fuses, and they're very robust.  If you bought (or
scrounged) a KXPA100 power supply cable, it would work well since it
has APPs on one end, already crimped on.

I've never had the problem you mentioned with the KXPA100's fuses.

Anyway, just an idea.

73,
matt W6NIA

On Mon, 16 Mar 2015 16:12:05 -0400, you wrote:

>My K3 is powered from a car battery as I am always /P. I have installed fast-blow fuses rated at 25 A in each of the supply lines.
>
>Operating at 80W RTTY this afternoon, I noted that I was getting a low voltage warning before I would have expected it. On examining the power cable, I found the fuse holders to be warm to the touch. I expect that is what was causing the voltage drop.
>
>However, may I ask what specific (make , model) of fuse holders are you using to protect your k3?
>
>73
>John, KK4OYJ
>
>
>______________________________________________________________
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Matt Zilmer, W6NIA
--
"Always store beer in a dark place."  -R. Heinlein

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[Elecraft mailing list]

John, out of curiosity.What size wire you are using, and how long is the wire between the Radio and the Battery?

PS:  Contrary to what some believe, the FUSE in a power cable is not there to protect the Radio.
         But there to protect the " Power Cable " from starting a fire.

((((73)))) Milverton / W9MMS

      From: J <[hidden email]>
 To: "'John, 9H5G'" <[hidden email]>; [hidden email]
 Sent: Monday, March 16, 2015 3:16 PM
 Subject: Re: [Elecraft] K3 power supply fuses
   
You might closely examine the type of connections inside the holders.  Some
aftermarket automotive fuse holders have poorly crimped connections and
might pass a quick resistance check, but....

73,
Jay
W6CJ

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of John,
9H5G
Sent: Monday, March 16, 2015 13:12
To: <[hidden email]>
Subject: [Elecraft] K3 power supply fuses

My K3 is powered from a car battery as I am always /P. I have installed
fast-blow fuses rated at 25 A in each of the supply lines.

Operating at 80W RTTY this afternoon, I noted that I was getting a low
voltage warning before I would have expected it. On examining the power
cable, I found the fuse holders to be warm to the touch. I expect that is
what was causing the voltage drop.

However, may I ask what specific (make , model) of fuse holders are you
using to protect your k3?

73
John, KK4OYJ


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[Bill Frantz]

I power my K3 from three sealed lead-acid batteries charged from
a solar panel. I have an inline fuse holder for automotive fuses
in the plus lead to each of the batteries. They have "OES"
stamped into the plastic covers.

If the fuse holders are warm to the touch, and there is not
other source of heat nearby, then you have your smoking gun and
that is where your problem lies. To trouble shoot this class of
problems, measure voltage drops through the power supply wiring
system. If there is a largish drop anywhere, find out why and
correct it.

I had to trouble shoot my battery setup with a dummy load and a
brick on a straight key to discovered that the RigRunner part of
the system wasn't able to carry full transmit load. Now there is
a wire directly from the battery junction connector to the K3.

Note that in an automotive installation, you need to fuse both
the positive and negative leads. Fusing the positive lead is
enough to cover most of the obvious failures -- radio develops
dead short, a bare wire touches chassis etc. If the lead between
the negative side of the battery and the chassis of the car (or
a bolt on the engine) becomes loose, then when cranking the
starter, the current from the starter may find a route through
your antenna connection, radio and back to the battery. You want
a fuse that will blow if this rare situation occurs.

73 Bill AE6JV

On 3/16/15 at 1:12 PM, [hidden email] (John, 9H5G) wrote:

>My K3 is powered from a car battery as I am always /P. I have
>installed fast-blow fuses rated at 25 A in each of the supply lines.
>
>Operating at 80W RTTY this afternoon, I noted that I was
>getting a low voltage warning before I would have expected it.
>On examining the power cable, I found the fuse holders to be
>warm to the touch. I expect that is what was causing the
>voltage drop.
-----------------------------------------------------------------------
Bill Frantz        | Truth and love must prevail  | Periwinkle
[phone]      | over lies and hate.          | 16345
Englewood Ave
www.pwpconsult.com |               - Vaclav Havel | Los Gatos,
CA 95032

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[Rick WA6NHC]

I use 40A  self-resetting automotive circuit breakers (pos/neg) in my
truck (not the K Line station) which protects the wiring nicely, are
sealed and I've never had to muss with them.  I then fuse the radios, at
the radios, with the appropriate fuses.

Rick wa6nhc

On 3/16/2015 2:18 PM, Bill Frantz wrote:
>
> Note that in an automotive installation, you need to fuse both the
> positive and negative leads.

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[k6dgw]

I've been using the automotive blade-type fuses for several years and
find them to be very low resistance which remains constant over time.
The wiping action also keeps the contacts clean.  They're the ones in
the RigRunner distribution boxes.  In-line cartridge fuse holders are
problematical.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org

On 3/16/2015 1:12 PM, John, 9H5G wrote:

> However, may I ask what specific (make , model) of fuse holders are
> you using to protect your k3?
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[Gary Gregory-2]

Fred,
As are lead acid batteries.

I have been using AGM batteries for years now with the K3 plus blade fuses
also.

Portable ops 24/7 here....

Gary
Vk1ZZ
K3, KX3, KPA500-FT, KAT500-FT,P3.
On 17/03/2015 9:06 AM, "Fred Jensen" <[hidden email]> wrote:

> I've been using the automotive blade-type fuses for several years and find
> them to be very low resistance which remains constant over time. The wiping
> action also keeps the contacts clean.  They're the ones in the RigRunner
> distribution boxes.  In-line cartridge fuse holders are problematical.
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
> - www.cqp.org
>
> On 3/16/2015 1:12 PM, John, 9H5G wrote:
>
>  However, may I ask what specific (make , model) of fuse holders are
>> you using to protect your k3?
>>
> ______________________________________________________________
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>

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[Don Wilhelm-4]

John,

If your fuseholders are of the 3AG type, consider replacing them with
the blade type fuseholders which have much better contact resistance
characteristics.  The in-line 3AG fuseholders often do not have
sufficient pressure contact with the ends of the fuse for a good
connection.  Poor connections to the fuse will cause the fuseholders to
heat and also cause extra voltage drops in the power cable.

73,
Don W3FPR

On 3/16/2015 4:12 PM, John, 9H5G wrote:

> My K3 is powered from a car battery as I am always /P. I have installed fast-blow fuses rated at 25 A in each of the supply lines.
>
> Operating at 80W RTTY this afternoon, I noted that I was getting a low voltage warning before I would have expected it. On examining the power cable, I found the fuse holders to be warm to the touch. I expect that is what was causing the voltage drop.
>
> However, may I ask what specific (make , model) of fuse holders are you using to protect your k3?
>
> 73
> John, KK4OYJ
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>

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