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Mobile Grounding for KX3 and KXPA100

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Tad Smedes

Mobile Grounding for KX3 and KXPA100

I am planning to use my KX3 and KXPA100 powered by Budipole PowerMini
and LiFEPO4 battery for field day this year and have a question about
grounding. When I am using them both at the home station they are
grounded to each other and every other piece of equipment in the shack
using a ground bar and copper straps. When I use my KX3 by itself
mobile I have never grounded it and never had an issue. Is there
anything special that I need to do do when I hook the KX3 to the KXPA100
while mobile, and what is it? and or what do the rest of you do when
running mobile with a KX3 and KXPA100 for grounding?

--
*Thanks -Tad Smedes K8TCS N-Scale*

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Bob McGraw - K4TAX

Re: Mobile Grounding for KX3 and KXPA100

I do agree that the radio, the amp should be connected to the power
source negative as "ground". As to connecting to mother earth, it is
the antenna that works against earth. Thus if you are using a center
fed dipole, no mother earth connection is needed.   If you are using an
OCFD antenna, a good balun plus a common mode choke at the feed point
plus a common mode choke before the amp/radio is required.   If you are
using a vertical or inverted L, then a real ground system with radials
is required for the antenna to work against. If you are using a random
length of wire thus end fed, then a real ground system is needed.   A
single driven ground rod IS NOT a good ground system for any antenna.

As to grounding the radio and amp...............nah, not needed if all
else is correct.

73

Bob, K4TAX

On 6/11/2018 4:09 PM, Smedes, Tad - Comcast wrote:

> I am planning to use my KX3 and KXPA100 powered by Budipole PowerMini
> and LiFEPO4 battery for field day this year and have a question about
> grounding. When I am using them both at the home station they are
> grounded to each other and every other piece of equipment in the shack
> using a ground bar and copper straps. When I use my KX3 by itself
> mobile I have never grounded it and never had an issue. Is there
> anything special that I need to do do when I hook the KX3 to the
> KXPA100 while mobile, and what is it? and or what do the rest of you
> do when running mobile with a KX3 and KXPA100 for grounding?
>

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Don Wilhelm

Re: Mobile Grounding for KX3 and KXPA100

In reply to this post by Tad Smedes

Tad,

For Field Day, you may want to add a strap between the KX3 and the
KXPA100 to reduce noise pickup on the cables between them. If running
on batteries, that should be sufficient. If running on a generator, you
COULD connect a heavy wire between the KXPA100 and the ground rod for
the generator (do not drive a separate ground rod because it can cause
an AC hazard). As for lightning protection, the normal Field Day
precaution that I know is to disconnect antennas and turn off the
equipment when that is nearby lightning.

For your mobile installation, I don't think many mobile hams do any
grounding. If you feel you need it, ground to the vehicle with a strap.
A mobile station is "battery powered" and a ground is not normally needed.

Remember that a ground is only for AC safety and lightning protection,
and normally demands that a connection to Mother Earth is needed and
that any extra driver ground rods must all be connected wwith heavy wire
to the Utility Entrance ground rod.
The only equivalent in a generator powered Field Day installation is a
ground rod at the generator. There is no equivalent for mobile operation.

73,
Don W3FPR

On 6/11/2018 5:09 PM, Smedes, Tad - Comcast wrote:

> I am planning to use my KX3 and KXPA100 powered by Budipole PowerMini
> and LiFEPO4 battery for field day this year and have a question about
> grounding. When I am using them both at the home station they are
> grounded to each other and every other piece of equipment in the shack
> using a ground bar and copper straps. When I use my KX3 by itself
> mobile I have never grounded it and never had an issue. Is there
> anything special that I need to do do when I hook the KX3 to the KXPA100
> while mobile, and what is it? and or what do the rest of you do when
> running mobile with a KX3 and KXPA100 for grounding?
>

Jim Brown-10

Re: Mobile Grounding for KX3 and KXPA100

In reply to this post by Tad Smedes

On 6/11/2018 2:09 PM, Smedes, Tad - Comcast wrote:
> I am planning to use my KX3 and KXPA100 powered by Budipole PowerMini
> and LiFEPO4 battery for field day this year and have a question about
> grounding. When I am using them both at the home station they are
> grounded to each other and every other piece of equipment in the shack
> using a ground bar and copper straps.

Let's use the right words for the right things we do. BONDING is what
we are doing when we may an electrically short and mechanically robust
connection between equipment and between all of the grounds in our
home. GROUNDING is a connection to Mother Earth. It's purpose is
Lightning Protection.

> When I use my KX3 by itself mobile I have never grounded it and never
> had an issue.

In general, radio equipment should be bonded together, but should NOT be
bonded to the vehicle. You MUST run a pair of big wires direct from the
battery to the rig. NEVER use the vehicle chassis as a path for return
DC current -- that's a recipe for disaster! The only connection to the
vehicle should usually be the coax shield to the best metal you can find
at the antenna, because the metal in the car body acts as the
counterpoise for your antenna. In other words, it is PART OF the
antenna! Make sure that whatever metal you bond to actually goes to the
rest of the car's chassis. That's often not easy -- even when there are
metal to metal mechanical connections, they're often insulated from each
other by paint!

> Is there anything special that I need to do do when I hook the KX3 to
> the KXPA100 while mobile, and what is it? and or what do the rest of
> you do when running mobile with a KX3 and KXPA100 for grounding?

73, Jim K9YC

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K8TE

Re: Mobile Grounding for KX3 and KXPA100

In reply to this post by Tad Smedes

The exception (There are always exceptions!) to what Bob writes below is
the type of vertical which requires a counterpoise, but not radials such as
quarter-wave. This would include verticals like the Cushcraft R8. These
do require a ground for static discharge protection. But, as Jim, K9Y, has
pointed out numerous times, this ground is NOT for the antenna's
operation/radiation. Buy Ward Silver's, N0AX, book on Bonding and
Grounding, if you can find it. Jim's web site is free!

Don's advice on lightning is paramount for safety! If lightning is within
10 miles, disconnect all antenna cables, and enjoy your food, beer, reading
material, etc. We had two Airmen killed at Canon AFB NM when this
requirement was ignored. Disconnecting antennas during last year's FD for
five hours dropped us out of the Top 20 in 1A by one! However, unlike two
years previous, we suffered not equipment damage and, most importantly, no
operator damage.

Sadly, the Cibola National Forest just announced it will close down (about
95%) this Friday due to extreme fire danger. I am seeking an alternative
that meets our criteria. An EOC sounds enticing. We will not operate in a
parking lot in North Central NM!

--
73, Bill, K8TE
Albuquerque DX Association, W5UR

Message: 18
Date: Mon, 11 Jun 2018 16:41:02 -0500
From: Bob McGraw K4TAX <[hidden email]>
To: [hidden email]
Subject: Re: [Elecraft] Mobile Grounding for KX3 and KXPA100
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=utf-8; format=flowed

I do agree that the radio, the amp should be connected to the power
source negative as "ground".? As to connecting to mother earth, it is
the antenna that works against earth.? Thus if you are using a center
fed dipole, no mother earth connection is needed.?? If you are using an
OCFD antenna, a good balun plus a common mode choke at the feed point
plus a common mode choke before the amp/radio is required.?? If you are
using a vertical or inverted L, then a real ground system with radials
is required for the antenna to work against.? If you are using a random
length of wire thus end fed, then a real ground system is needed.?? A
single? driven ground rod IS NOT a good ground system for any antenna.

As to grounding the radio and amp...............nah, not needed if all
else is correct.

73

Bob, K4TAX
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