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KX3 vehicle mount

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rcbenedict1545

KX3 vehicle mount

Newer cars that have the auto stop feature ( engine turns off at stop lights) have a sensor between battery negative and car frame. In these cars the radio has to be connected to frame ground not the battery negative post or the sensor will not work right correctly.

Ray
W8LYJ

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Jim Brown-10

Re: KX3 vehicle mount

Not necessarily. There is no good reason to bond the radio to the
vehicle. It is, however, necessary to have good RF connection at the
antenna between the coax shield and the body so that it can act as a
counterpoise. That connection could be through a good RF capacitor. In
this were done, I see no reason why powering the radio directly from the
battery would be problematic, or would interfere with that system.

Also, it seems to me that the system you describe is only viable with
electric or hybrid vehicles. There are other significantly greater
issues with installation of a HF radio in these vehicles.

73, Jim K9YC

On Mon,9/12/2016 1:57 PM, Gmail wrote:
> Newer cars that have the auto stop feature ( engine turns off at stop lights) have a sensor between battery negative and car frame. In these cars the radio has to be connected to frame ground not the battery negative post or the sensor will not work right correctly.

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Josh Fiden

Re: KX3 vehicle mount

Hi Jim,

It's not just hybrid & electric vehicles. Some newer conventional cars
shut the engine off during idle to save fuel. There's a sensor inline
with the battery neg terminal to measure charge & discharge rates to
prevent the start-stop algorithm from causing a dead battery. If you
connect direct to the battery, you will confuse the sensor.

73,
Josh W6XU

On 9/12/2016 2:52 PM, Jim Brown wrote:

> Not necessarily. There is no good reason to bond the radio to the
> vehicle. It is, however, necessary to have good RF connection at the
> antenna between the coax shield and the body so that it can act as a
> counterpoise. That connection could be through a good RF capacitor. In
> this were done, I see no reason why powering the radio directly from
> the battery would be problematic, or would interfere with that system.
>
> Also, it seems to me that the system you describe is only viable with
> electric or hybrid vehicles. There are other significantly greater
> issues with installation of a HF radio in these vehicles.
>
> 73, Jim K9YC
>
> On Mon,9/12/2016 1:57 PM, Gmail wrote:
>> Newer cars that have the auto stop feature ( engine turns off at stop
>> lights) have a sensor between battery negative and car frame. In
>> these cars the radio has to be connected to frame ground not the
>> battery negative post or the sensor will not work right correctly.
>

Jim Brown-10

Re: KX3 vehicle mount

Thanks Josh.

To confuse the sensor, it seems to me that the sensor would need to be
built into the battery lug, so that it was between where we could
connect our 12V minus lead and the battery -- i.e., so that our current
was going through it. I was assuming it was on the wire side of the
battery lug. I haven't seen one of these things, so I must plead ignorance.

Thanks and 73, Jim

On Mon,9/12/2016 5:01 PM, Josh Fiden wrote:
> Hi Jim,
>
> It's not just hybrid & electric vehicles. Some newer conventional cars
> shut the engine off during idle to save fuel. There's a sensor inline
> with the battery neg terminal to measure charge & discharge rates to
> prevent the start-stop algorithm from causing a dead battery. If you
> connect direct to the battery, you will confuse the sensor.
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Josh Fiden

Re: KX3 vehicle mount

How I understand it is that the sensor is measuring charge/discharge
current of the battery.

The following assumes the radio is connected directly to the battery
terminal:

Case 1. If the alternator is running, then current to the radio is
passing through the sensor which looks like charging current to the battery.

Case 2. If the alternator is not running, then the current to the radio
is discharging the battery, but not being registered by the sensor.

If instead we connect the radio's negative supply to the chassis ground
side of the sensor, then the sensor can correctly measure when the radio
is discharging the battery.

Caveat: my understanding of this is from the fount of all knowledge,
i.e. I read about it on the internet! If I got it wrong, someone please
correct.

73,
Josh W6XU

On 9/12/2016 5:56 PM, Jim Brown wrote:

> Thanks Josh.
>
> To confuse the sensor, it seems to me that the sensor would need to be
> built into the battery lug, so that it was between where we could
> connect our 12V minus lead and the battery -- i.e., so that our
> current was going through it. I was assuming it was on the wire side
> of the battery lug. I haven't seen one of these things, so I must
> plead ignorance.
>
> Thanks and 73, Jim

Jim Brown-10

Re: KX3 vehicle mount

OK. In the absence of learning something different, I agree with your
analysis, Josh. One of the great things about sticking your neck out
and saying what you think you know is that when you're wrong, folks will
tell you about it. :)

Thanks!

73, Jim

On Mon,9/12/2016 7:40 PM, Josh Fiden wrote:

> How I understand it is that the sensor is measuring charge/discharge
> current of the battery.
>
> The following assumes the radio is connected directly to the battery
> terminal:
>
> Case 1. If the alternator is running, then current to the radio is
> passing through the sensor which looks like charging current to the
> battery.
>
> Case 2. If the alternator is not running, then the current to the
> radio is discharging the battery, but not being registered by the sensor.
>
> If instead we connect the radio's negative supply to the chassis
> ground side of the sensor, then the sensor can correctly measure when
> the radio is discharging the battery.
>
> Caveat: my understanding of this is from the fount of all knowledge,
> i.e. I read about it on the internet! If I got it wrong, someone
> please correct.
>
> 73,
> Josh W6XU
>
> On 9/12/2016 5:56 PM, Jim Brown wrote:
>> Thanks Josh.
>>
>> To confuse the sensor, it seems to me that the sensor would need to
>> be built into the battery lug, so that it was between where we could
>> connect our 12V minus lead and the battery -- i.e., so that our
>> current was going through it. I was assuming it was on the wire side
>> of the battery lug. I haven't seen one of these things, so I must
>> plead ignorance.
>>
>> Thanks and 73, Jim
>
> ______________________________________________________________
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>

thelastdb

Re: KX3 vehicle mount

In reply to this post by rcbenedict1545

I was once a 2-way radio tech and have installed over 1000 business band radios (yes, over one thousand) in my 15 or so years career. One thing we, the companies I've worked for, was NEVER to run a dedicated ground wire to the battery. We used a short ground wire from the radio and the local vehicle chassis.
From the 100W Motrac/Mastr II/SyntorX (and many others) all used the chassis as a return path. Only once did I have a problem. Once a Low band unit (39MHz) with a magnetic mount (NMO-40) came back because the excess ground wire was coiled into a nice inductor. (I installed that one). Caused all sorts of RFI in the broadcast radio etc.
Just a data point on thousands and thousands of industrial, commercial and public safety radio installs out there doing it that way.
Myron WVØHPrinted on Recycled Data -------- Original message --------From: Jim Brown <[hidden email]> Date: 9/12/2016 8:58 PM (GMT-07:00) To: [hidden email] Subject: Re: [Elecraft] KX3 vehicle mount
OK. In the absence of learning something different, I agree with your
analysis, Josh. One of the great things about sticking your neck out
and saying what you think you know is that when you're wrong, folks will
tell you about it. :)

Thanks!

73, Jim

On Mon,9/12/2016 7:40 PM, Josh Fiden wrote:

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Don Wilhelm

Re: KX3 vehicle mount

Myron,

Good points.

For those who choose not to trust the conductivity of the vehicle
chassis local ground point, run the negative wire to a point on the
vehicle chassis near the point where the battery to chassis ground wire
is mounted - but not to the battery terminal itself nor the battery to
chassis cable mounting point. Create a new ground point near the
battery to chassis wire and bite into the metal with an adequate star
washer for a low resistance connection - no fuse in the negative wire.

This is the recommendation of W8JI Tom Rauch who has also installed many
mobile radio systems (commercial and amateur). See
http://www.w8ji.com/mobile_ground.htm as has been mentioned previously.

73,
Don W3FPR

On 9/12/2016 11:29 PM, thelastdb wrote:
> I was once a 2-way radio tech and have installed over 1000 business band radios (yes, over one thousand) in my 15 or so years career. One thing we, the companies I've worked for, was NEVER to run a dedicated ground wire to the battery. We used a short ground wire from the radio and the local vehicle chassis.
> From the 100W Motrac/Mastr II/SyntorX (and many others) all used the chassis as a return path. Only once did I have a problem. Once a Low band unit (39MHz) with a magnetic mount (NMO-40) came back because the excess ground wire was coiled into a nice inductor. (I installed that one). Caused all sorts of RFI in the broadcast radio etc.
>

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Jim Brown-10

Re: KX3 vehicle mount

In reply to this post by thelastdb

VHF/UHF is a VERY different animal with respect to RFI to and from a
vehicle's electronics. Using the vehicle's chassis as the return for
power is a recipe for serious problems. Yes, it carries DC just fine,
but it forms a BIG loop that is a sitting duck for all the RF trash in
the vehicle.

73, Jim K9YC

On Mon,9/12/2016 8:29 PM, thelastdb wrote:
> I was once a 2-way radio tech and have installed over 1000 business
> band radios (yes, over one thousand) in my 15 or so years career. One
> thing we, the companies I've worked for, was NEVER to run a dedicated
> ground wire to the battery. We used a short ground wire from the radio
> and the local vehicle chassis.

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Edward R Cole

Re: KX3 Vehicle mount

In reply to this post by rcbenedict1545

Very timely discussion as I am installing my KX3 into a 2015 truck.

I already installed a new Alinco DR-735T. Temporarily using a dc
accessory plug for power and not running low RF output as the dc plug
wiring is not large enough for the current required for 50w (dc
outlet is clearly provided for charging cell phones or other low
current devices).

But I bought some No. 8awg wire to run from the battery to a power
distribution connector (which I already installed). Per the w8ji
article I should run the No. 8 negative wire to a chassis ground in
proximity to the battery ground (but not directly to the battery neg terminal).

I can do that. However the DR-735T power cord has both pos and neg
lead fuses. Should I eliminate the neg fuse for the radio? (and on
all neg lines to each radio component I am installing?). I have a
main fuse for the pos lead that will be connected at the battery,
plus each radio item has individual fuses on pos leads rated for
their current draw.

Equipment location is about 12 feet from the battery (crew cab
pickup) so that is a lot chassis for current to flow thru, so I feel
running a dedicated neg wire to the engine compartment chassis is
better than a short ground wire to nearby chassis (which would have
to be on exterior of the cab as there is no exposed metal in the
interior). That would be subject to corrosion from exposure. Under
hood chassis is better protected from direct exposure to the elements
(I live in an area where road salt is applied in winter).

BTW I recall installing the trunk mount 50w and 100w VHF MOT radios
that used the chassis ground wire. Also recall installs in 24v
ground-start heavy equipment (D8's, frontloaders, and
roadgraders). We installed high current steering diodes to prevent
24v flowing thru the radio ground.

I will be mounting the KX3 at the dash of my F250 Ford using a
combination or RAM mounts and ProClip dash bracket. I will have
photos and description on my website in a few days to show that. My
KX3 has add on heat sink which makes the exterior dimension 3/4 inch
higher, so the std RAM mount is not able to accommodate this. I am
using some HB 1/8-inch thick aluminum tabs to extend the RAM mounting
"fingers" which might be of interest to others with this predicament.

73, Ed - KL7UW

----------------
From: Fred Moore <[hidden email]>
To: [hidden email]
Subject: Re: [Elecraft] KX3 Vehicle mount
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=windows-1252

Brian, if you run the negative lead all the way to the battery (direct)
fuse the lead close to the battery. If you run the negative lead to
point that ends in a frame ground do not fuse the negative lead. This
does not conflict with standard automotive manufacture recommendations.

Also carefully read almost all manufactures installations it says run
the leads to the battery, and they provide two fuses on in the positive
and negative lead. I have not seen an installation manual in years that
didn't say directly to the battery..

Tom W8JI has some good explanations on they why's and how this came to be

http://www.w8ji.com/mobile_ground.htm

Regards.. Fred

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

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Don Wilhelm

Re: KX3 Vehicle mount

Ed,

Yes, eliminate the fuse in the negative wire and ground it to the
chassis near the point where the battery negative is grounded.

Consider that the radio will also be grounded by the connection of the
coax shield to the chassis. If the negative power lead is fused and
that fuse opens, current can still flow to the radio, but by a very
circuitous path and that is not 'goodness' .

73,
Don W3FPR

On 9/13/2016 3:54 AM, Edward R Cole wrote:

> But I bought some No. 8awg wire to run from the battery to a power
> distribution connector (which I already installed). Per the w8ji
> article I should run the No. 8 negative wire to a chassis ground in
> proximity to the battery ground (but not directly to the battery neg
> terminal).
>
> I can do that. However the DR-735T power cord has both pos and neg
> lead fuses. Should I eliminate the neg fuse for the radio? (and on
> all neg lines to each radio component I am installing?). I have a main
> fuse for the pos lead that will be connected at the battery, plus each
> radio item has individual fuses on pos leads rated for their current
> draw.

Elecraft mailing list

Re: KX3 Vehicle mount

In reply to this post by rcbenedict1545

My KX3 mount in a 2008 Tacoma
7th District QSO Party 2016 with KX3

The Amp is on the hump in the back Access cab portion.

|
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| | |

|

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7th District QSO Party 2016 with KX3
19 new photos added to shared album | |

|

|

From: Edward R Cole <[hidden email]>
To: [hidden email]
Sent: Tuesday, September 13, 2016 12:54 AM
Subject: Re: [Elecraft] KX3 Vehicle mount

Very timely discussion as I am installing my KX3 into a 2015 truck.

I already installed a new Alinco DR-735T. Temporarily using a dc
accessory plug for power and not running low RF output as the dc plug
wiring is not large enough for the current required for 50w (dc
outlet is clearly provided for charging cell phones or other low
current devices).

But I bought some No. 8awg wire to run from the battery to a power
distribution connector (which I already installed). Per the w8ji
article I should run the No. 8 negative wire to a chassis ground in
proximity to the battery ground (but not directly to the battery neg terminal).

I can do that. However the DR-735T power cord has both pos and neg
lead fuses. Should I eliminate the neg fuse for the radio? (and on
all neg lines to each radio component I am installing?). I have a
main fuse for the pos lead that will be connected at the battery,
plus each radio item has individual fuses on pos leads rated for
their current draw.

Equipment location is about 12 feet from the battery (crew cab
pickup) so that is a lot chassis for current to flow thru, so I feel
running a dedicated neg wire to the engine compartment chassis is
better than a short ground wire to nearby chassis (which would have
to be on exterior of the cab as there is no exposed metal in the
interior). That would be subject to corrosion from exposure. Under
hood chassis is better protected from direct exposure to the elements
(I live in an area where road salt is applied in winter).

BTW I recall installing the trunk mount 50w and 100w VHF MOT radios
that used the chassis ground wire. Also recall installs in 24v
ground-start heavy equipment (D8's, frontloaders, and
roadgraders). We installed high current steering diodes to prevent
24v flowing thru the radio ground.

I will be mounting the KX3 at the dash of my F250 Ford using a
combination or RAM mounts and ProClip dash bracket. I will have
photos and description on my website in a few days to show that. My
KX3 has add on heat sink which makes the exterior dimension 3/4 inch
higher, so the std RAM mount is not able to accommodate this. I am
using some HB 1/8-inch thick aluminum tabs to extend the RAM mounting
"fingers" which might be of interest to others with this predicament.

73, Ed - KL7UW

----------------
From: Fred Moore <[hidden email]>
To: [hidden email]
Subject: Re: [Elecraft] KX3 Vehicle mount
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=windows-1252

Brian, if you run the negative lead all the way to the battery (direct)
fuse the lead close to the battery. If you run the negative lead to
point that ends in a frame ground do not fuse the negative lead. This
does not conflict with standard automotive manufacture recommendations.

Also carefully read almost all manufactures installations it says run
the leads to the battery, and they provide two fuses on in the positive
and negative lead. I have not seen an installation manual in years that
didn't say directly to the battery..

Tom W8JI has some good explanations on they why's and how this came to be

http://www.w8ji.com/mobile_ground.htm

Regards.. Fred

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

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