[Elecraft] KX3 Vehicle mount

[Edward R Cole]

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 <fred at fmeco.com>
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] KX3 Vehicle mount
Message-ID: <daf7143d-4e9d-4841-7264-ec7ec94cc776 at fmeco.com>
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
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