K3 inline fuse

classic Classic list List threaded Threaded
20 messages Options
Reply | Threaded
Open this post in threaded view
|

K3 inline fuse

Chris W7CTH
Hi, I am ready to apply 12v for the first time to my new K3. Should I have a
inline fuse on the DC to the K3? and if so what amp.
Just don't look right not to have a fuse inline.

Thanks
Chris W7CTH



     
______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

km5ps
On 8/11/2010 6:32 PM, Chris Hembree wrote:

> Hi, I am ready to apply 12v for the first time to my new K3. Should I have a
> inline fuse on the DC to the K3? and if so what amp.
> Just don't look right not to have a fuse inline.
>
> Thanks
> Chris W7CTH
>
>
>
>
> ______________________________________________________________
> 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
>    
If you have one, it probably would not hurt to do so.  I put one on mine
just in case.
john
km5ps
______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

David Cutter
In reply to this post by Chris W7CTH
You are much better off using the current limiting feature of your dc
supply.  A fuse is not fast enough to protect any electronic circuitry.
Strictly speaking a fuse in line is rated to protect the cable in the event
of a short circuit in the rig which would be a very big fuse, far bigger
than your psu is rated to supply most likely.  Fuses and their holders are
too slow and drop valuable volts along with the cable drop and connectors,
which all add up to a poorer distortion figure on transmit.

David
G3UNA

> Hi, I am ready to apply 12v for the first time to my new K3. Should I have
> a
> inline fuse on the DC to the K3? and if so what amp.
> Just don't look right not to have a fuse inline.
>
> Thanks
> Chris W7CTH
>
>
______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

ab2tc
I completely agree with you. The inline fuses are there for mobile installations where you have a direct connection to the car battery. On my ICOM radios I have always shortened the power cable removing the inline fuse in the process.

AB2TC - Knut

David Cutter wrote
You are much better off using the current limiting feature of your dc
supply.  A fuse is not fast enough to protect any electronic circuitry.
Strictly speaking a fuse in line is rated to protect the cable in the event
of a short circuit in the rig which would be a very big fuse, far bigger
than your psu is rated to supply most likely.  Fuses and their holders are
too slow and drop valuable volts along with the cable drop and connectors,
which all add up to a poorer distortion figure on transmit.

David
G3UNA
<snip>
Mel
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

Mel
Follow the instructions and check the + terminal to - with an ohm meter for any shorts.  The problem you face is the transistor is the worlds fastest fuse and on initial turn on you are looking at a low current surge as the unit charges the supply and decoupling caps.  A full current rated fuse will not protect the PCB if you did something wrong, nor will current limit if set for the max current the K3 will draw on transmit. 

If you test the resistance first, the chances are you will be safe on initial power up.  Like one suggested using a current limiting PS set say at 3 amps, that will protect you adequately.  When the K3 comes alive, you can increase the current limit to operating conditions.  I hope this helps.

Mel

--- On Thu, 8/12/10, ab2tc <[hidden email]> wrote:

From: ab2tc <[hidden email]>
Subject: Re: [Elecraft] K3 inline fuse
To: [hidden email]
Date: Thursday, August 12, 2010, 3:13 PM


I completely agree with you. The inline fuses are there for mobile
installations where you have a direct connection to the car battery. On my
ICOM radios I have always shortened the power cable removing the inline fuse
in the process.

AB2TC - Knut


David Cutter wrote:

>
> You are much better off using the current limiting feature of your dc
> supply.  A fuse is not fast enough to protect any electronic circuitry.
> Strictly speaking a fuse in line is rated to protect the cable in the
> event
> of a short circuit in the rig which would be a very big fuse, far bigger
> than your psu is rated to supply most likely.  Fuses and their holders are
> too slow and drop valuable volts along with the cable drop and connectors,
> which all add up to a poorer distortion figure on transmit.
>
> David
> G3UNA
> <snip>
>

--
View this message in context: http://elecraft.365791.n2.nabble.com/K3-inline-fuse-tp5414371p5418061.html
Sent from the [K3] mailing list archive at Nabble.com.
______________________________________________________________
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



     
______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

Matt Zilmer
In reply to this post by Chris W7CTH
The best method is Wayne's suggestion from way back:

In both Neg and Pos leads, supply a fuseholder and fuse.  I use the
"stubby" fuses from Motorola @ 30A, you should use something like
that.  These are T-rated, meaning they're designed to open with a DC
load.  Don't use a fuse out of your home's fusebox...

General setup:
12V AGM Battery @ 110 AH, cabled to a set of panel-mounted MOT inline
fuse holders.  Each lead is covered by a 30A fuse.  The battery is
charged by solar power, two Siemens SR50 (50W) panels on the roof of
the shack.

Note: This recommendation is a little more permanent than what you're
probably looking for right now.  

If you're interested in this approach, I can probably get you the part
numbers you need.  MOT has a service center in IL, and you can phone
in your order.

73,
matt W6NIA

On Wed, 11 Aug 2010 16:32:12 -0700 (PDT), you wrote:

>Hi, I am ready to apply 12v for the first time to my new K3. Should I have a
>inline fuse on the DC to the K3? and if so what amp.
>Just don't look right not to have a fuse inline.
>
>Thanks
>Chris W7CTH
>
>
>
>      
>______________________________________________________________
>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
______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

W8JI
Positive lead fuses are a good idea.

Negative lead fuses never were a good idea unless the radio has a totally
floating negative buss.

If the negative lead fuse to the radio opens for any reason all the negative
lead current for the radio will flow through the negative lead of any
accessories connected to the power supply.

They are a terrible idea for any system with the negative lead common to
ports in and out of the radio, or to the chassis. You certainly won't catch
me using one!The negative lead needs to be connected solidly to the power
supply negative for a multitude of reasons, the most prominent of which is
if the negative lead fuse to the radio opens you can blow up accessories or
open ground traces including traces in the radio.

They are not even recommended in vehicles any longer in some countries
because of the fire and damage hazard they create.

73 Tom

> In both Neg and Pos leads, supply a fuseholder and fuse.  I use the
> "stubby" fuses from Motorola @ 30A, you should use something like
> that.  These are T-rated, meaning they're designed to open with a DC
> load.  Don't use a fuse out of your home's fusebox...

______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

Don Wilhelm-4
Tom,

You are absolutely correct.  Take a mobile situation - the radio's power
ground is connected to the transceiver chassis ground, as is the coax
shield, microphone shield and other stuff.  All that "stuff" can (and
will) connect to the vehicle chassis at some point.  I know the coax
will connect at the point where it attaches to the antenna.

Now imagine a situation where the negative lead fuse is open.  The
vehicle chassis is still connected to the battery negative - so the
radio gets it positive lead directly from the battery (since that fuse
is still good), but the negative battery terminal voltage flows through
the vehicle chassis to the point where the coax shield connects to the
vehicle chassis (presumably at the antenna), and then follows the coax
shield to the transceiver.  The transceiver still works, so you (the
operator) are not aware that the negative fuse has opened, but the DC
current paths will give rise to "strange happenings".

Bottom line, follow Tom's advice and fuse only the positive lead, and in
a mobile situation, take the negative voltage from the vehicle chassis
close to the radio.

The fusing of the negative lead started when some were concerned about
the vehicle's battery to engine block (or vehicle chassis) connection is
broken, which could lead to massive starting motor currents being
conducted from the coax ground at the mobile antenna, through the radio,
and onto the battery negative terminal.  Yes, that situation is quite
real, but can be circumvented by periodically checking the engine block
to chassis grounding in the vehicle, as well as the battery negative
connection to the vehicle chassis.

If the radio has an isolated (floating) negative connection (I believe
only commercial mobile radios do that), then fusing of the negative lead
is OK, but for most ham radios, the fusing of the negative lead can
cause as much damage as the reasons given for inserting a fuse into the
negative lead.  Take your pick.

73,
Don W3FPR

Tom W8JI wrote:

> Positive lead fuses are a good idea.
>
> Negative lead fuses never were a good idea unless the radio has a totally
> floating negative buss.
>
> If the negative lead fuse to the radio opens for any reason all the negative
> lead current for the radio will flow through the negative lead of any
> accessories connected to the power supply.
>
> They are a terrible idea for any system with the negative lead common to
> ports in and out of the radio, or to the chassis. You certainly won't catch
> me using one!The negative lead needs to be connected solidly to the power
> supply negative for a multitude of reasons, the most prominent of which is
> if the negative lead fuse to the radio opens you can blow up accessories or
> open ground traces including traces in the radio.
>
> They are not even recommended in vehicles any longer in some countries
> because of the fire and damage hazard they create.
>
> 73 Tom
>
>  
>> In both Neg and Pos leads, supply a fuseholder and fuse.  I use the
>> "stubby" fuses from Motorola @ 30A, you should use something like
>> that.  These are T-rated, meaning they're designed to open with a DC
>> load.  Don't use a fuse out of your home's fusebox...
>>    
>
> ______________________________________________________________
> 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
>
>  
______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

David Cutter
Good advice from you both on battery fusing, particularly in vehicles, but
you've drifted off the subject a little.
Chris W7CTH said:
"Hi, I am ready to apply 12v for the first time to my new K3. "

I would use a current-limited power supply to connect up ANY equipment for
the first time.  No fuse is as fast as electronic limiting.

Even the fastest semiconductor fuses require a huge overload to achieve a
sluggish response.  Busman 25A fuse: 340A^2t.  I'm not an expert, but divide
340 by the time you want it break and then take the square root, I think
that's how it's done.  So, to blow in 100ms it takes 58A.  Someone put me
right.  UK 13A plug fuses need 2.1 x 13A to guarantee to blow in 30seconds!

David
G3UNA






> Tom,
>
> You are absolutely correct.  Take a mobile situation - the radio's power
> ground is connected to the transceiver chassis ground, as is the coax
> shield, microphone shield and other stuff.  All that "stuff" can (and
> will) connect to the vehicle chassis at some point.  I know the coax
> will connect at the point where it attaches to the antenna.
>
> Now imagine a situation where the negative lead fuse is open.  The
> vehicle chassis is still connected to the battery negative - so the
> radio gets it positive lead directly from the battery (since that fuse
> is still good), but the negative battery terminal voltage flows through
> the vehicle chassis to the point where the coax shield connects to the
> vehicle chassis (presumably at the antenna), and then follows the coax
> shield to the transceiver.  The transceiver still works, so you (the
> operator) are not aware that the negative fuse has opened, but the DC
> current paths will give rise to "strange happenings".
>
> Bottom line, follow Tom's advice and fuse only the positive lead, and in
> a mobile situation, take the negative voltage from the vehicle chassis
> close to the radio.
>
> The fusing of the negative lead started when some were concerned about
> the vehicle's battery to engine block (or vehicle chassis) connection is
> broken, which could lead to massive starting motor currents being
> conducted from the coax ground at the mobile antenna, through the radio,
> and onto the battery negative terminal.  Yes, that situation is quite
> real, but can be circumvented by periodically checking the engine block
> to chassis grounding in the vehicle, as well as the battery negative
> connection to the vehicle chassis.
>
> If the radio has an isolated (floating) negative connection (I believe
> only commercial mobile radios do that), then fusing of the negative lead
> is OK, but for most ham radios, the fusing of the negative lead can
> cause as much damage as the reasons given for inserting a fuse into the
> negative lead.  Take your pick.
>
> 73,
> Don W3FPR
>
> Tom W8JI wrote:
>> Positive lead fuses are a good idea.
>>
>> Negative lead fuses never were a good idea unless the radio has a totally
>> floating negative buss.
>>
>> If the negative lead fuse to the radio opens for any reason all the
>> negative
>> lead current for the radio will flow through the negative lead of any
>> accessories connected to the power supply.
>>
>> They are a terrible idea for any system with the negative lead common to
>> ports in and out of the radio, or to the chassis. You certainly won't
>> catch
>> me using one!The negative lead needs to be connected solidly to the power
>> supply negative for a multitude of reasons, the most prominent of which
>> is
>> if the negative lead fuse to the radio opens you can blow up accessories
>> or
>> open ground traces including traces in the radio.
>>
>> They are not even recommended in vehicles any longer in some countries
>> because of the fire and damage hazard they create.
>>
>> 73 Tom
>>

______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

gm3sek
David Cutter wrote:

>
>I would use a current-limited power supply to connect up ANY equipment
>for the first time.  No fuse is as fast as electronic limiting.
>
>Even the fastest semiconductor fuses require a huge overload to achieve
>a sluggish response.  Busman 25A fuse: 340A^2t.  I'm not an expert, but
>divide 340 by the time you want it break and then take the square root,
>I think that's how it's done.  So, to blow in 100ms it takes 58A.
>Someone put me right.  UK 13A plug fuses need 2.1 x 13A to guarantee to
>blow in 30seconds!
>

The other important point is that fuses provide ZERO protection until
AFTER they have blown. In the life and death of a semiconductor, even a
few milliseconds is a very long time indeed.


--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

Chris W7CTH
In reply to this post by David Cutter
I did not have a current-limited power supply. Just a Astrom rs-35m. anyway I
just went for it and everything worked out okay.
all my ohm reading were all in the safe range and I did take my time to make
sure I did eveything right.

K3 turned on okay.
Chris




________________________________
From: David Cutter <[hidden email]>
To: [hidden email]; Tom W8JI <[hidden email]>
Cc: [hidden email]; Chris Hembree <[hidden email]>
Sent: Fri, August 13, 2010 12:33:33 AM
Subject: Re: [Elecraft] K3 inline fuse

Good advice from you both on battery fusing, particularly in vehicles, but
you've drifted off the subject a little.
Chris W7CTH said:
"Hi, I am ready to apply 12v for the first time to my new K3. "

I would use a current-limited power supply to connect up ANY equipment for the
first time.  No fuse is as fast as electronic limiting.

Even the fastest semiconductor fuses require a huge overload to achieve a
sluggish response.  Busman 25A fuse: 340A^2t.  I'm not an expert, but divide 340
by the time you want it break and then take the square root, I think that's how
it's done.  So, to blow in 100ms it takes 58A.  Someone put me right.  UK 13A
plug fuses need 2.1 x 13A to guarantee to blow in 30seconds!

David
G3UNA






> Tom,
>
> You are absolutely correct.  Take a mobile situation - the radio's power
> ground is connected to the transceiver chassis ground, as is the coax
> shield, microphone shield and other stuff.  All that "stuff" can (and
> will) connect to the vehicle chassis at some point.  I know the coax
> will connect at the point where it attaches to the antenna.
>
> Now imagine a situation where the negative lead fuse is open.  The
> vehicle chassis is still connected to the battery negative - so the
> radio gets it positive lead directly from the battery (since that fuse
> is still good), but the negative battery terminal voltage flows through
> the vehicle chassis to the point where the coax shield connects to the
> vehicle chassis (presumably at the antenna), and then follows the coax
> shield to the transceiver.  The transceiver still works, so you (the
> operator) are not aware that the negative fuse has opened, but the DC
> current paths will give rise to "strange happenings".
>
> Bottom line, follow Tom's advice and fuse only the positive lead, and in
> a mobile situation, take the negative voltage from the vehicle chassis
> close to the radio.
>
> The fusing of the negative lead started when some were concerned about
> the vehicle's battery to engine block (or vehicle chassis) connection is
> broken, which could lead to massive starting motor currents being
> conducted from the coax ground at the mobile antenna, through the radio,
> and onto the battery negative terminal.  Yes, that situation is quite
> real, but can be circumvented by periodically checking the engine block
> to chassis grounding in the vehicle, as well as the battery negative
> connection to the vehicle chassis.
>
> If the radio has an isolated (floating) negative connection (I believe
> only commercial mobile radios do that), then fusing of the negative lead
> is OK, but for most ham radios, the fusing of the negative lead can
> cause as much damage as the reasons given for inserting a fuse into the
> negative lead.  Take your pick.
>
> 73,
> Don W3FPR
>
> Tom W8JI wrote:
>> Positive lead fuses are a good idea.
>>
>> Negative lead fuses never were a good idea unless the radio has a totally
>> floating negative buss.
>>
>> If the negative lead fuse to the radio opens for any reason all the negative
>> lead current for the radio will flow through the negative lead of any
>> accessories connected to the power supply.
>>
>> They are a terrible idea for any system with the negative lead common to
>> ports in and out of the radio, or to the chassis. You certainly won't catch
>> me using one!The negative lead needs to be connected solidly to the power
>> supply negative for a multitude of reasons, the most prominent of which is
>> if the negative lead fuse to the radio opens you can blow up accessories or
>> open ground traces including traces in the radio.
>>
>> They are not even recommended in vehicles any longer in some countries
>> because of the fire and damage hazard they create.
>>
>> 73 Tom
>>


     
______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

Jim Brown-10
In reply to this post by gm3sek
On Fri, 13 Aug 2010 11:08:04 +0100, Ian White GM3SEK wrote:

>The other important point is that fuses provide ZERO protection until
>AFTER they have blown. In the life and death of a semiconductor, even a
>few milliseconds is a very long time indeed.

Yes. On the other hand, boards are all pre-tested at the factory, and
assembly instructions included several resistance checks, which I suspect
are carefully selected to expose any faults that may have happened during
assembly.

73, Jim K9YC


______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

gdaught6
In reply to this post by gm3sek
Ian wrote...

> The other important point is that fuses provide ZERO protection until
> AFTER they have blown. In the life and death of a semiconductor, even a
> few milliseconds is a very long time indeed.

I like to tell the story about a series of tests we did when I worked at Fairchild, in
Silicon Valley.  Our little VHF silicon transistors were very expensive, and quite
fragile.  We tested many fuses to identify which one(s) would be suitable protection
for the transistors.  To summarize:  transistors are a very effective way of protecting
fuses!

73,

George T Daughters, K6GT
CU in the California QSO Party (CQP)
October 2-3, 2010


______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

David Cutter
A transistor is the fastest fuse on 3 legs, beats a 2-legged fuse any day.

David
G3UNA

> I like to tell the story about a series of tests we did when I worked at
> Fairchild, in
> Silicon Valley.  Our little VHF silicon transistors were very expensive,
> and quite
> fragile.  We tested many fuses to identify which one(s) would be suitable
> protection
> for the transistors.  To summarize:  transistors are a very effective way
> of protecting
> fuses!
>
> 73,
>
> George T Daughters, K6GT
> CU in the California QSO Party (CQP)
> October 2-3, 2010

______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

Cookie
In reply to this post by gdaught6
The transistor is the most probable reason for the fuse blowing but the fuse may save the other components and semi conductors as well as the circuit board.  The original query stated he would be using an Astron 35 which has a current limiter but limiting the current to 35 amps will still allow a lot of damage.

Sent from my iPhone

On Aug 13, 2010, at 9:55, [hidden email] wrote:

> Ian wrote...
>
>> The other important point is that fuses provide ZERO protection until
>> AFTER they have blown. In the life and death of a semiconductor, even a
>> few milliseconds is a very long time indeed.
>
> I like to tell the story about a series of tests we did when I worked at Fairchild, in
> Silicon Valley.  Our little VHF silicon transistors were very expensive, and quite
> fragile.  We tested many fuses to identify which one(s) would be suitable protection
> for the transistors.  To summarize:  transistors are a very effective way of protecting
> fuses!
>
> 73,
>
> George T Daughters, K6GT
> CU in the California QSO Party (CQP)
> October 2-3, 2010
>
>
> ______________________________________________________________
> 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
______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse current limiting

W8JI
In reply to this post by Chris W7CTH
If you do not have an **adjustable** current limited supply, do what I do on
the bench.

I have a 35 amp limited supply on the bench, and my 13.8 volt buss has jacks
that are direct, through a 10 ohm 10 watt resistor, and through a second 10
ohm in series with that.

I can get a really good idea if something is going to power up OK because I
can start with 20 ohms, move the tap to 10 ohms, and then add a jumper plug
to make it 5 ohms. My supply also is variable voltage, and although it only
goes down to 9 volts (and up to 18) that still helps.

Many things do not show with a resistance test, but a resistor limited test
will show problems with popping bigger transistors or foil traces.

______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

Joe Planisky
In reply to this post by Cookie
One thing that hasn't been mentioned is that the K3 has a built-in 6A  
fuse for the basic rig and a separate 20A circuit breaker for the  
KPA3.  So it's not like there's no protection at all between the APP  
connector and the internal circuits.

73
--
Joe KB8AP

On Aug 13, 2010, at 9:02 AM, Willis wrote:

> The transistor is the most probable reason for the fuse blowing but  
> the fuse may save the other components and semi conductors as well  
> as the circuit board.  The original query stated he would be using  
> an Astron 35 which has a current limiter but limiting the current to  
> 35 amps will still allow a lot of damage.
>
> Sent from my iPhone
>
> On Aug 13, 2010, at 9:55, [hidden email] wrote:
>
>> Ian wrote...
>>
>>> The other important point is that fuses provide ZERO protection  
>>> until
>>> AFTER they have blown. In the life and death of a semiconductor,  
>>> even a
>>> few milliseconds is a very long time indeed.
>>
>> I like to tell the story about a series of tests we did when I  
>> worked at Fairchild, in
>> Silicon Valley.  Our little VHF silicon transistors were very  
>> expensive, and quite
>> fragile.  We tested many fuses to identify which one(s) would be  
>> suitable protection
>> for the transistors.  To summarize:  transistors are a very  
>> effective way of protecting
>> fuses!
>>
>> 73,
>>
>> George T Daughters, K6GT
>> CU in the California QSO Party (CQP)
>> October 2-3, 2010
>>
>>
>> ______________________________________________________________
>> 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
> ______________________________________________________________
> 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

______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K3 inline fuse

Jan Erik Holm
In reply to this post by David Cutter
Amen!  Best so far.
Let´s move on.....
/ James
---------
On 2010-08-13 17:01, David Cutter wrote:

> A transistor is the fastest fuse on 3 legs, beats a 2-legged fuse any day.
>
> David
> G3UNA
>
>> I like to tell the story about a series of tests we did when I worked at
>> Fairchild, in
>> Silicon Valley.  Our little VHF silicon transistors were very expensive,
>> and quite
>> fragile.  We tested many fuses to identify which one(s) would be suitable
>> protection
>> for the transistors.  To summarize:  transistors are a very effective way
>> of protecting
>> fuses!
>>
>> 73,
>>
>> George T Daughters, K6GT
>> CU in the California QSO Party (CQP)
>> October 2-3, 2010
>
______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Elecraft] K3 DVR Audio

Roy Davis
In reply to this post by W8JI
Hello,

I don't know if this subject has been briught up, if it has please excuse my
not seeing it.

The DVR for my K3 put in place today has an anomoly.  It makes recordings
for on the air transmissions fine.  But it seems to have what sounds like a
popping or staticy presence to the audio.  The quality of the audio itself
is great.

The problem exists whether the K3 is in transmit or test mode.

Has anyone had the same experience and a fix.

I plan to take the K3 to Costa Rica at TI5N , for the SSB Contest, and would
like to clear up the problem before leaving.

Thanks,
Roy - WK4Y
K3 #1366

______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: Elecraft] K3 DVR Audio

Nr4c
My experience is that the DVR has almost perfect reproduction of the audio.
I have not noticed any unusual sounds, nothing that was not in the original
input.

Note, if you are going to record you "CQ" and/or "EXCHANGE", turn "OFF" or
ZERO out any TX EQ before recording.  The TX will add the TX EQ when you
transmit.  If you record with TX EQ, it will EQ it again when you transmit.
The K3/DVR combination can provide excellent audio recording such that the
guy on the other end will not know you are not "Live".  Unlike so many
operators on contests that have entirely different sound quality on
playback.

...bill  nr4c

-----Original Message-----
From: Roy Davis [mailto:[hidden email]]
Sent: Sunday, February 20, 2011 9:11 PM
To: [hidden email]
Subject: [Elecraft] Elecraft] K3 DVR Audio

Hello,

I don't know if this subject has been briught up, if it has please excuse my

not seeing it.

The DVR for my K3 put in place today has an anomoly.  It makes recordings
for on the air transmissions fine.  But it seems to have what sounds like a
popping or staticy presence to the audio.  The quality of the audio itself
is great.

The problem exists whether the K3 is in transmit or test mode.

Has anyone had the same experience and a fix.

I plan to take the K3 to Costa Rica at TI5N , for the SSB Contest, and would

like to clear up the problem before leaving.

Thanks,
Roy - WK4Y
K3 #1366

______________________________________________________________
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

______________________________________________________________
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