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K3: reverse 12 volt supply

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K3: reverse 12 volt supply

Whew!

Not a good feeling-but it can happen to any of us, regardless of how careful
we are.

Elecraft has been very good on suggesting helpful modifications to the
radio. Any thoughts? Perhaps an in-line diode?

I'm not sure if that would result in a significant voltage drop-just a
thought.

'73 de JIM N2ZZ

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of roger
wood
Sent: Sunday, September 13, 2015 1:24 PM
To: Elecraft
Subject: [Elecraft] K3: reverse 12 volt supply

I managed to connect a 12 volt car battery backwards to the K3.

There was a lot of smoke and the breaker popped. The RX and TX appear to
have survived, however the internal 100 Watt amplifier now shows an
over-current fault and quickly switches off. I haven't dared open it up yet
- far too depressed now. I'll leave it till next weekend.

Any comments on what I might expect to find inside and how to idiot-proof it
for my future operation?

73
Roger
KK3RW / G3WEW
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Don Wilhelm-4

Re: K3: reverse 12 volt supply

The base K3 is protected by an in-line diode that will not allow reverse
voltage to flow.
The same is not true of the KPA3 where the reduction in voltage would
not be tolerable.
The KPA3 is protected by a circuit breaker, but in this case did not
trip in time to prevent damage.

73,
Don W3FPR

On 9/13/2015 10:55 PM, James F. Boehner MD via Elecraft wrote:

> Whew!
>
> Not a good feeling-but it can happen to any of us, regardless of how careful
> we are.
>
> Elecraft has been very good on suggesting helpful modifications to the
> radio. Any thoughts? Perhaps an in-line diode?
>
> I'm not sure if that would result in a significant voltage drop-just a
> thought.
>
>

Richard Fjeld-2

Re: K3: reverse 12 volt supply

I would think you could wire a relay with a diode in the path to the
coil so that it would not operate
if the polarity of the power leads are reversed. That way, there would
be negligible voltage drop when operated.

Dick,n0ce

On 9/13/2015 10:09 PM, Don Wilhelm wrote:

> The base K3 is protected by an in-line diode that will not allow
> reverse voltage to flow.
> The same is not true of the KPA3 where the reduction in voltage would
> not be tolerable.
> The KPA3 is protected by a circuit breaker, but in this case did not
> trip in time to prevent damage.
>
> 73,
> Don W3FPR
>
> On 9/13/2015 10:55 PM, James F. Boehner MD via Elecraft wrote:
>> Whew!
>>
>> Not a good feeling-but it can happen to any of us, regardless of how
>> careful
>> we are.
>>
>> Elecraft has been very good on suggesting helpful modifications to the
>> radio. Any thoughts? Perhaps an in-line diode?
>>
>> I'm not sure if that would result in a significant voltage drop-just a
>> thought.
>>
>>
>
> ______________________________________________________________
> 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]

Roger D Johnson

Re: K3: reverse 12 volt supply

In reply to this post by Don Wilhelm-4

On 9/14/2015 2:42 PM, Roger D Johnson wrote:

> According to the schematic, there is a shunt diode on the PA board. Hopefully, it
> prevented the full 12 volts from appearing on the circuitry. The smoke probably
> came from the chokes ahead of the diode.
>
> 73, Roger
>
>
> On 9/13/2015 11:09 PM, Don Wilhelm wrote:
>> The base K3 is protected by an in-line diode that will not allow reverse
>> voltage to flow.
>> The same is not true of the KPA3 where the reduction in voltage would not be
>> tolerable.
>> The KPA3 is protected by a circuit breaker, but in this case did not trip in
>> time to prevent damage.
>>
>> 73,
>> Don W3FPR
>>
>>

Fred Townsend-2

Re: K3: reverse 12 volt supply

In reply to this post by Richard Fjeld-2

Dick:
Relays? Sure, easy to do. Power relays are often used in many kinds
equipment. They are sometimes called 'contactors'. They are either big and
clunky or small and unreliable. Which kind do you want and what are you
willing to pay?
73
Fred, AE6QL

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of
Richard Fjeld
Sent: Monday, September 14, 2015 1:01 AM
To: [hidden email]
Subject: Re: [Elecraft] K3: reverse 12 volt supply

I would think you could wire a relay with a diode in the path to the coil so
that it would not operate if the polarity of the power leads are reversed.
That way, there would be negligible voltage drop when operated.

Dick,n0ce

On 9/13/2015 10:09 PM, Don Wilhelm wrote:

> The base K3 is protected by an in-line diode that will not allow
> reverse voltage to flow.
> The same is not true of the KPA3 where the reduction in voltage would
> not be tolerable.
> The KPA3 is protected by a circuit breaker, but in this case did not
> trip in time to prevent damage.
>
> 73,
> Don W3FPR
>
> On 9/13/2015 10:55 PM, James F. Boehner MD via Elecraft wrote:
>> Whew!
>>
>> Not a good feeling-but it can happen to any of us, regardless of how
>> careful we are.
>>
>> Elecraft has been very good on suggesting helpful modifications to
>> the radio. Any thoughts? Perhaps an in-line diode?
>>
>> I'm not sure if that would result in a significant voltage drop-just
>> a thought.
>>
>>
>
> ______________________________________________________________
> 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

Re: K3: reverse 12 volt supply

You guys are working too hard on this. Here goes:
Take a bridge rectifier, preferably a Schottky with proper current and voltage rating. Tie the + to the radio + tie the - to the radio -. And I don't care what polarity you put on the AC terminals it always give the radio the proper polarity, I put a little box on the back of every portable radio when we go camping etc. That is after my brother reversed the polarity on my TS-50 and we let the smoke out.
Mel, K6KBE

From: Fred Townsend <[hidden email]>
To: 'Richard Fjeld' <[hidden email]>; [hidden email]
Sent: Monday, September 14, 2015 3:13 PM
Subject: Re: [Elecraft] K3: reverse 12 volt supply

Dick:
Relays? Sure, easy to do. Power relays are often used in many kinds
equipment. They are sometimes called 'contactors'. They are either big and
clunky or small and unreliable. Which kind do you want and what are you
willing to pay?
73
Fred, AE6QL

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of
Richard Fjeld
Sent: Monday, September 14, 2015 1:01 AM
To: [hidden email]
Subject: Re: [Elecraft] K3: reverse 12 volt supply

I would think you could wire a relay with a diode in the path to the coil so
that it would not operate if the polarity of the power leads are reversed.
That way, there would be negligible voltage drop when operated.

Dick,n0ce

On 9/13/2015 10:09 PM, Don Wilhelm wrote:

> The base K3 is protected by an in-line diode that will not allow
> reverse voltage to flow.
> The same is not true of the KPA3 where the reduction in voltage would
> not be tolerable.
> The KPA3 is protected by a circuit breaker, but in this case did not
> trip in time to prevent damage.
>
> 73,
> Don W3FPR
>
> On 9/13/2015 10:55 PM, James F. Boehner MD via Elecraft wrote:
>> Whew!
>>
>> Not a good feeling-but it can happen to any of us, regardless of how
>> careful we are.
>>
>> Elecraft has been very good on suggesting helpful modifications to
>> the radio. Any thoughts? Perhaps an in-line diode?
>>
>> I'm not sure if that would result in a significant voltage drop-just
>> a thought.
>>
>>
>
> ______________________________________________________________
> 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]

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Ian

Re: K3: reverse 12 volt supply

Try this: http://ad5x.com/images/Articles/Vprotect.pdf
73, Ian N8IK

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Mel Farrer via Elecraft
Sent: Monday, September 14, 2015 18:31
To: Fred Townsend <[hidden email]>; 'Richard Fjeld' <[hidden email]>; [hidden email]
Subject: Re: [Elecraft] K3: reverse 12 volt supply

You guys are working too hard on this. Here goes:
Take a bridge rectifier, preferably a Schottky with proper current and voltage rating. Tie the + to the radio + tie the - to the radio -. And I don't care what polarity you put on the AC terminals it always give the radio the proper polarity, I put a little box on the back of every portable radio when we go camping etc. That is after my brother reversed the polarity on my TS-50 and we let the smoke out.
Mel, K6KBE

From: Fred Townsend <[hidden email]>
To: 'Richard Fjeld' <[hidden email]>; [hidden email]
Sent: Monday, September 14, 2015 3:13 PM
Subject: Re: [Elecraft] K3: reverse 12 volt supply

Dick:
Relays? Sure, easy to do. Power relays are often used in many kinds equipment. They are sometimes called 'contactors'. They are either big and clunky or small and unreliable. Which kind do you want and what are you willing to pay?
73
Fred, AE6QL

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Richard Fjeld
Sent: Monday, September 14, 2015 1:01 AM
To: [hidden email]
Subject: Re: [Elecraft] K3: reverse 12 volt supply

I would think you could wire a relay with a diode in the path to the coil so that it would not operate if the polarity of the power leads are reversed.
That way, there would be negligible voltage drop when operated.

Dick,n0ce

On 9/13/2015 10:09 PM, Don Wilhelm wrote:

> The base K3 is protected by an in-line diode that will not allow
> reverse voltage to flow.
> The same is not true of the KPA3 where the reduction in voltage would
> not be tolerable.
> The KPA3 is protected by a circuit breaker, but in this case did not
> trip in time to prevent damage.
>
> 73,
> Don W3FPR
>
> On 9/13/2015 10:55 PM, James F. Boehner MD via Elecraft wrote:
>> Whew!
>>
>> Not a good feeling-but it can happen to any of us, regardless of how
>> careful we are.
>>
>> Elecraft has been very good on suggesting helpful modifications to
>> the radio. Any thoughts? Perhaps an in-line diode?
>>
>> I'm not sure if that would result in a significant voltage drop-just
>> a thought.
>>
>>
>
> ______________________________________________________________
> 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]

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Richard Fjeld-2

Re: K3: reverse 12 volt supply

In reply to this post by Fred Townsend-2

It was a passing thought as; how to use a diode without causing a
voltage drop was the original question.

AD5X has an OVP and Rev Polarity project on his website that would be
better.

I couldn't think of the call sign at the time, so I suggested a relay.

(I've worked with huge contactors that were on motor-generators to
prevent run-aways)

73,
Dick, n0ce

On 9/14/2015 5:13 PM, Fred Townsend wrote:

> Dick:
> Relays? Sure, easy to do. Power relays are often used in many kinds
> equipment. They are sometimes called 'contactors'. They are either big and
> clunky or small and unreliable. Which kind do you want and what are you
> willing to pay?
> 73
> Fred, AE6QL
>
>
>

ae4pb

Re: K3: reverse 12 volt supply

I have an idea. Why not color code the wires so we know which one is
positive and which one is Ground (or neutral) ? Maybe make the positive lead
red (like hot, danger) and the other one anything, black, green...
Thoughts?

Notice: The above post is a weak attempt at humor, albiet sarcastic , and is
NOT INTENDED TO BE OFFENSIVE IN ANY WAY.

Jerry Moore
AE4PB, K3S SN# TBA later TOMORROW!!

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of
Richard Fjeld
Sent: Tuesday, September 15, 2015 1:02 AM
To: Fred Townsend; [hidden email]
Subject: Re: [Elecraft] K3: reverse 12 volt supply

It was a passing thought as; how to use a diode without causing a voltage
drop was the original question.

AD5X has an OVP and Rev Polarity project on his website that would be
better.

I couldn't think of the call sign at the time, so I suggested a relay.

(I've worked with huge contactors that were on motor-generators to prevent
run-aways)

73,
Dick, n0ce

On 9/14/2015 5:13 PM, Fred Townsend wrote:

> Dick:
> Relays? Sure, easy to do. Power relays are often used in many kinds
> equipment. They are sometimes called 'contactors'. They are either big
> and clunky or small and unreliable. Which kind do you want and what
> are you willing to pay?
> 73
> Fred, AE6QL
>
>
>

Gary Gregory-2

Re: K3: reverse 12 volt supply

What an interesting idea. Wonder why that has not become a standard?

(grin)

Gary

-----Original Message-----
From: "[hidden email]" <[hidden email]>
Sent: ‎15/‎09/‎2015 10:18 PM
To: "'Richard Fjeld'" <[hidden email]>; "'Fred Townsend'" <[hidden email]>; "[hidden email]" <[hidden email]>
Subject: Re: [Elecraft] K3: reverse 12 volt supply

I have an idea. Why not color code the wires so we know which one is
positive and which one is Ground (or neutral) ? Maybe make the positive lead
red (like hot, danger) and the other one anything, black, green...
Thoughts?

Notice: The above post is a weak attempt at humor, albiet sarcastic , and is
NOT INTENDED TO BE OFFENSIVE IN ANY WAY.

Jerry Moore
AE4PB, K3S SN# TBA later TOMORROW!!

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of
Richard Fjeld
Sent: Tuesday, September 15, 2015 1:02 AM
To: Fred Townsend; [hidden email]
Subject: Re: [Elecraft] K3: reverse 12 volt supply

It was a passing thought as; how to use a diode without causing a voltage
drop was the original question.

AD5X has an OVP and Rev Polarity project on his website that would be
better.

I couldn't think of the call sign at the time, so I suggested a relay.

(I've worked with huge contactors that were on motor-generators to prevent
run-aways)

73,
Dick, n0ce

On 9/14/2015 5:13 PM, Fred Townsend wrote:

______________________________________________________________
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Don Wilhelm-4

Re: K3: reverse 12 volt supply

In reply to this post by ae4pb

But that does not match the markings on a battery which is usually
marked with "+" at the positive terminal.:-)

73,
Don W3FPR

On 9/15/2015 8:14 AM, [hidden email] wrote:
> I have an idea. Why not color code the wires so we know which one is
> positive and which one is Ground (or neutral) ? Maybe make the positive lead
> red (like hot, danger) and the other one anything, black, green...
> Thoughts?
>
>

______________________________________________________________
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Charlie T, K3ICH

Re: K3: reverse 12 volt supply

In reply to this post by Gary Gregory-2

Seriously, it makes you wonder how the standard house wiring color code over here in the colonies ever came up with black as the hot wire.
Green for ground makes sense though.

73, Charlie k3ICH

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Gary
Sent: Tuesday, September 15, 2015 8:46 AM
To: [hidden email]; 'Richard Fjeld' <[hidden email]>; 'Fred Townsend' <[hidden email]>; [hidden email]
Subject: Re: [Elecraft] K3: reverse 12 volt supply

What an interesting idea. Wonder why that has not become a standard?

(grin)

Gary

-----Original Message-----
From: "[hidden email]" <[hidden email]>
Sent: ‎15/‎09/‎2015 10:18 PM
To: "'Richard Fjeld'" <[hidden email]>; "'Fred Townsend'" <[hidden email]>; "[hidden email]" <[hidden email]>
Subject: Re: [Elecraft] K3: reverse 12 volt supply

I have an idea. Why not color code the wires so we know which one is positive and which one is Ground (or neutral) ? Maybe make the positive lead red (like hot, danger) and the other one anything, black, green...
Thoughts?

Notice: The above post is a weak attempt at humor, albiet sarcastic , and is NOT INTENDED TO BE OFFENSIVE IN ANY WAY.

Jerry Moore
AE4PB, K3S SN# TBA later TOMORROW!!

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Richard Fjeld
Sent: Tuesday, September 15, 2015 1:02 AM
To: Fred Townsend; [hidden email]
Subject: Re: [Elecraft] K3: reverse 12 volt supply

It was a passing thought as; how to use a diode without causing a voltage drop was the original question.

AD5X has an OVP and Rev Polarity project on his website that would be better.

I couldn't think of the call sign at the time, so I suggested a relay.

(I've worked with huge contactors that were on motor-generators to prevent
run-aways)

73,
Dick, n0ce

On 9/14/2015 5:13 PM, Fred Townsend wrote:

______________________________________________________________
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Bob McGraw - K4TAX

Re: K3: reverse 12 volt supply

Black and white...... the ultimate in color contrast. White is neutral
or no color so what's left? Black. Yes green sorta make sense when
the grass is green but what about Winter when it is brown?

No wonder I've been confused all my life.

73
Bob, K4TAX
K3S s/n 10,163

On 9/15/2015 8:20 AM, Charlie T, K3ICH wrote:

> Seriously, it makes you wonder how the standard house wiring color code over here in the colonies ever came up with black as the hot wire.
> Green for ground makes sense though.
>
> 73, Charlie k3ICH
>
>
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Gary
> Sent: Tuesday, September 15, 2015 8:46 AM
> To: [hidden email]; 'Richard Fjeld' <[hidden email]>; 'Fred Townsend' <[hidden email]>; [hidden email]
> Subject: Re: [Elecraft] K3: reverse 12 volt supply
>
> What an interesting idea. Wonder why that has not become a standard?
>
> (grin)
>
> Gary
>
> -----Original Message-----
> From: "[hidden email]" <[hidden email]>
> Sent: ‎15/‎09/‎2015 10:18 PM
> To: "'Richard Fjeld'" <[hidden email]>; "'Fred Townsend'" <[hidden email]>; "[hidden email]" <[hidden email]>
> Subject: Re: [Elecraft] K3: reverse 12 volt supply
>
> I have an idea. Why not color code the wires so we know which one is positive and which one is Ground (or neutral) ? Maybe make the positive lead red (like hot, danger) and the other one anything, black, green...
> Thoughts?
>
>
>
>
>
>
> Notice: The above post is a weak attempt at humor, albiet sarcastic , and is NOT INTENDED TO BE OFFENSIVE IN ANY WAY.
>
> Jerry Moore
> AE4PB, K3S SN# TBA later TOMORROW!!
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Richard Fjeld
> Sent: Tuesday, September 15, 2015 1:02 AM
> To: Fred Townsend; [hidden email]
> Subject: Re: [Elecraft] K3: reverse 12 volt supply
>
> It was a passing thought as; how to use a diode without causing a voltage drop was the original question.
>
> AD5X has an OVP and Rev Polarity project on his website that would be better.
>
> I couldn't think of the call sign at the time, so I suggested a relay.
>
> (I've worked with huge contactors that were on motor-generators to prevent
> run-aways)
>
> 73,
> Dick, n0ce
>
>
>
> On 9/14/2015 5:13 PM, Fred Townsend wrote:
>> Dick:
>> Relays? Sure, easy to do. Power relays are often used in many kinds
>> equipment. They are sometimes called 'contactors'. They are either big
>> and clunky or small and unreliable. Which kind do you want and what
>> are you willing to pay?
>> 73
>> Fred, AE6QL
>>
>>
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
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Richard Fjeld-2

Re: K3: reverse 12 volt supply

In reply to this post by Don Wilhelm-4

I don't know the details of the guys who had the reversals.
I did a search for paired, stranded, two color wire for power lead use
and didn't come up with much.
Dick, n0ce

On 9/15/2015 8:16 AM, Don Wilhelm wrote:

> But that does not match the markings on a battery which is usually
> marked with "+" at the positive terminal.:-)
>
> 73,
> Don W3FPR
>
> On 9/15/2015 8:14 AM, [hidden email] wrote:
>> I have an idea. Why not color code the wires so we know which one is
>> positive and which one is Ground (or neutral) ? Maybe make the
>> positive lead
>> red (like hot, danger) and the other one anything, black, green...
>> Thoughts?
>>
>>
>

Don Wilhelm-4

Re: K3: reverse 12 volt supply

Dick,

The Wireman and several other wire distributors have red/black zip cord
in a variety of sizes from #24 to #10.
The #12 power wire that is supplied by Elecraft for the K3/K3S and
several other legacy kits is the red/black type.

73,
Don W3FPR

On 9/15/2015 1:49 PM, Richard Fjeld wrote:
> I don't know the details of the guys who had the reversals.
> I did a search for paired, stranded, two color wire for power lead use
> and didn't come up with much.
> Dick, n0ce
>
>

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Jim Brown-10

Re: K3: reverse 12 volt supply

On Tue,9/15/2015 11:55 AM, Walter Underwood wrote:
> Powerwerx has red/black zip cord from 24 gauge to 2 gauge.

Zip cord is NOT good for ANY application, because it is inherently
susceptible to RFI. TWISTED PAIR is FAR better, because it inherently
rejects interference from low audio frequencies to at least VHF. In the
last few years, I've been replacing more of my DC wiring with twisted
pair. I make it by putting black and white stranded THHN in a drill, the
other end in a vise, and twisting.

73, Jim K9YC
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N3XX

Re: K3: reverse 12 volt supply

In reply to this post by Richard Fjeld-2

Try here:
http://www.powerwerx.com/wire-cable/red-black-zip-cord.html

73,
Tim - N3XX

----- Original Message -----
From: "Richard Fjeld" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, September 15, 2015 1:49 PM
Subject: Re: [Elecraft] K3: reverse 12 volt supply

>I don't know the details of the guys who had the reversals.
> I did a search for paired, stranded, two color wire for power lead use
> and didn't come up with much.
> Dick, n0ce
>
>
> On 9/15/2015 8:16 AM, Don Wilhelm wrote:
>> But that does not match the markings on a battery which is usually
>> marked with "+" at the positive terminal.:-)
>>
>> 73,
>> Don W3FPR
>>
>> On 9/15/2015 8:14 AM, [hidden email] wrote:
>>> I have an idea. Why not color code the wires so we know which one is
>>> positive and which one is Ground (or neutral) ? Maybe make the
>>> positive lead
>>> red (like hot, danger) and the other one anything, black, green...
>>> Thoughts?
>>>
>>>
>>
>
> ______________________________________________________________
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Dale LeDoux

Re: K3: reverse 12 volt supply

In reply to this post by Charlie T, K3ICH

Black for ‘hot’ and white for ‘neutral’ really gets interesting when one steps from the shore onto recreational watercraft where for years that black wire was ‘hot’ on the 120 VAC system and the other black wire was the negative on the DC system. You can imagine the hilarity when these two were incorrectly identified.

Modern convention has the DC negative is yellow, but older boats are notoriously interesting to work on.

Dale
W5OHM

> On Sep 15, 2015, at 8:20 AM, Charlie T, K3ICH <[hidden email]> wrote:
>
> Seriously, it makes you wonder how the standard house wiring color code over here in the colonies ever came up with black as the hot wire.
> Green for ground makes sense though.
>
> 73, Charlie k3ICH
>
>
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Gary
> Sent: Tuesday, September 15, 2015 8:46 AM
> To: [hidden email]; 'Richard Fjeld' <[hidden email]>; 'Fred Townsend' <[hidden email]>; [hidden email]
> Subject: Re: [Elecraft] K3: reverse 12 volt supply
>
> What an interesting idea. Wonder why that has not become a standard?
>
> (grin)
>
> Gary
>
> -----Original Message-----
> From: "[hidden email]" <[hidden email]>
> Sent: ‎15/‎09/‎2015 10:18 PM
> To: "'Richard Fjeld'" <[hidden email]>; "'Fred Townsend'" <[hidden email]>; "[hidden email]" <[hidden email]>
> Subject: Re: [Elecraft] K3: reverse 12 volt supply
>
> I have an idea. Why not color code the wires so we know which one is positive and which one is Ground (or neutral) ? Maybe make the positive lead red (like hot, danger) and the other one anything, black, green...
> Thoughts?
>
>
>
>
>
>
> Notice: The above post is a weak attempt at humor, albiet sarcastic , and is NOT INTENDED TO BE OFFENSIVE IN ANY WAY.
>
> Jerry Moore
> AE4PB, K3S SN# TBA later TOMORROW!!
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Richard Fjeld
> Sent: Tuesday, September 15, 2015 1:02 AM
> To: Fred Townsend; [hidden email]
> Subject: Re: [Elecraft] K3: reverse 12 volt supply
>
> It was a passing thought as; how to use a diode without causing a voltage drop was the original question.
>
> AD5X has an OVP and Rev Polarity project on his website that would be better.
>
> I couldn't think of the call sign at the time, so I suggested a relay.
>
> (I've worked with huge contactors that were on motor-generators to prevent
> run-aways)
>
> 73,
> Dick, n0ce
>
>
>
> On 9/14/2015 5:13 PM, Fred Townsend wrote:
>> Dick:
>> Relays? Sure, easy to do. Power relays are often used in many kinds
>> equipment. They are sometimes called 'contactors'. They are either big
>> and clunky or small and unreliable. Which kind do you want and what
>> are you willing to pay?
>> 73
>> Fred, AE6QL
>>
>>
>>
>
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Elecraft mailing list

Re: K3: reverse 12 volt supply

In reply to this post by Don Wilhelm-4

Also all of the marine supply house carry color coded battery cables in a vinyl jacket.

Mel, K6KBE

From: Don Wilhelm <[hidden email]>
To: [hidden email]
Sent: Tuesday, September 15, 2015 11:22 AM
Subject: Re: [Elecraft] K3: reverse 12 volt supply

Dick,

The Wireman and several other wire distributors have red/black zip cord
in a variety of sizes from #24 to #10.
The #12 power wire that is supplied by Elecraft for the K3/K3S and
several other legacy kits is the red/black type.

73,
Don W3FPR

On 9/15/2015 1:49 PM, Richard Fjeld wrote:
> I don't know the details of the guys who had the reversals.
> I did a search for paired, stranded, two color wire for power lead use
> and didn't come up with much.
> Dick, n0ce
>
>

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Robin Moseley

Re: K3: reverse 12 volt supply

In reply to this post by Jim Brown-10

as the cables are side by side and very close.. twisting won't make an
iota of difference.

you are wasting your time twisting the wires..

If you need to remove RFI then use a ferrite choke.

Robin G1MHU

-----Original Message-----
From: Jim Brown
Sent: Tuesday, September 15, 2015 8:05 PM
To: [hidden email]
Subject: Re: [Elecraft] K3: reverse 12 volt supply

On Tue,9/15/2015 11:55 AM, Walter Underwood wrote:
> Powerwerx has red/black zip cord from 24 gauge to 2 gauge.

Zip cord is NOT good for ANY application, because it is inherently
susceptible to RFI. TWISTED PAIR is FAR better, because it inherently
rejects interference from low audio frequencies to at least VHF. In the
last few years, I've been replacing more of my DC wiring with twisted
pair. I make it by putting black and white stranded THHN in a drill, the
other end in a vise, and twisting.

73, Jim K9YC
______________________________________________________________
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