Big Truck Radio 12V Source Upgrade

[slowmover]

Semi-truck tractors come pre-wired with a fused 10A or 15A harness which connects to a standard radio cord via binding posts (in almost all cases).

Problem is that it’s both noisy (from fuse panel), and consists of a minimal wire gauge which allows for a greater than .5V (3%) volt drop while in use.

Chasing noise is ongoing. Quietest possible receive means an upgrade here is usually worthwhile. It’s a lot of work, however.

From Engine Off to Engine On there is usually some noise introduced with HVAC running and items inverter-powered being detectable:

https://palomar-engineers.com/wp-content/uploads/Palomar-Engineers-Common-Mode-Noise-on-Coax-User-Diagnosis-Test-1.pdf

I wouldn’t say it’s the amount or intensity base station operators encounter while at home, but the difficulty of an antenna ground plane (RF Bond) makes the following worthwhile, IMO. I’ve had to do it on the last (6) tractors I’ve driven.

Establish Radio Location & 12V Ground Point.

Negative
I’ve been able thus far (KW, Pete & FTL) to find a location to drill & use a stainless with screw plus lock washer & flat washers for 12V ground. Whether I’ve drilled thru the cab curtain track into the overhead console or used a right angle adapter, it’s a matter of easiest closest to the radio location. It’s not hard to find a place to drill that’s inconspicuous.

A). Test with meter.
B). Want to access it easily enough with radio in place (wire slack).
C). 1-2’ on average Neg length.

This ALONE can be adapted with the factory harness for fastest results if testing shows a difference. POS still from OEM, but new ground with new jumper installed between OEM & Radio cords.

Positive

1). From the radio location, trace out the distance down the drivers A-pillar to the floor (except on Freightliner where one takes it down the passenger-side A-pillar).

2). The cab wiring exit is the air line panel.
One will route through an unused hole. Study the exit from under the hood). Get the distance from radio to panel on interior; exactness not necessary.

3). From the panel exterior (underhood) the run is to the battery box under the drivers door via existing wire harnesses. I usually have to crank the Steer Tire hard to Starboard to access the space sufficiently to get this measurement (rough, but be generous).

4). Now, from the battery box, the same exit for the power harness you traced to a 12V Battery Positive easy to reach plus some slack.

The average length of the fused Positive lead has been 18-19’ in my experience. So I suggest not buying less than 25’ to account for both Pos & Neg as it’ll be 20’ shortest for planning. Use entire 25’ to run the Pos as getting behind interior panels and making right-angle turns consumes length quickly.

In fact it’s “better”, IMO, to spec additional wire length to accommodate some noise filtering near the radio by wrapping several turns (as many as possible) through a large Mix 31 snap-over ferrite.

(Continued)

 

[slowmover]

(Install Post #2)

Ferrite Snap-Over Bead

I’ve used the Palomar Engineer FSB-31-1-1 for the last several installations and always observed noise reduction.




After the power has been successfully routed and interior panels replaced is when I wrap & zip-tie this extending from the radio such that it’s out of the way and won’t move while underway (it’s “heavy”).

Want to be able to remove radio far enough to pull power cord free.

The Proper Split Beads to Suppress RFI

Wire Quality & Gauge

I use the USCG rules of non-soldered wire connections and graded quality of wiring. Vibration kills soldered connections. Quality tools have their place.

1). “Marine Grade Wiring” is high strand-count, highly flexible, in an oil & gas resistant cover. ANCOR is the best known brand (other sources exist).

2). Heat Shrink covered terminations. Solid terminations in re corrosion resistance. (Again, ANCOR).

3). Split Loom Wire Cover . Flame-resistant (graded) is best.

4. Zip Ties (Ty Wraps). Bundle of 50 or 100 or so as the first routing attempts may require remove and re-do. Support every 8-10” as possible.

— Wire Gauge required will depend on fused amp draw requirements. The fuse introduces a little resistance, and the “general heat” (not engine heat) of summertime running adds a little.

If the radio system is fused for 10A and a 21’ total circuit length is needed, then a minimum 10-AWG wire is required.

Conductors Sized (AWG) for 3% Voltage Drop

Conductors Sized (AWG) for 3% Voltage Drop

www.marinco.com

The maximum potential amp draw is how to size. May rarely or almost never need it. But age and corrosion and vibration are always with us.

Radio systems work best with 13.8V or a little higher. If the electrical delivery falls below 13.0V, the power system isn’t done correctly. (Engine running).


Careful routing to avoid pinch points is crucial. Most big trucks aren’t hard, per se, it’s just time-consuming. Give yourself a couple of days to deal with frustrations.

If the pic below looks intimidating, then that’s maybe enough exploration on your part. OTOH, if one understands that it looks “bad” but mainly is just junk behind the kick panel, it’s not so bad.



Removing the sill plate (screws), loosening the kick panel cover (screws), and popping out the firewall cover gives access to the loosened A-pillar cover (remove weather-stripping partway and secure (don’t remove entirely).

In this pic the air line panel is up near the clutch pivot.

If you’re also installing new coax, this’ll be part of the procedure.

Yes, you can “avoid” this by running the power line external to the panels, but it may not look right or possibly be snagged at some point. You aren’t going to remove this. At worst you’ll cut off both ends when you get out of this truck moving to another.

The A-pillar/floor/kick panel junction is the hard part to get past, power or coax. Access and then re-attach is the time-killer once coax and power are routed successfully.

Start at the battery and work inwards.

Follow and attach to existing wire bundles to air line panel.

Use zip ties your harness won’t come loose except to attach fused end at BATT. (Not “tight” so much as secured).

Use grommet to cushion thru panel.

Take your time from air panel interior to get across and start up pillar (biggest PITA).

Adequate slack all the way up. Usually can push this one-wire harness into gap between panel cover and glass.

Where to get it into the overhead console varies by make to keep it hidden. It’ll be obvious given a little time.

Freightliner there is no advantage in “quiet” by going to the battery. I’ve done it both ways. It’s best, IMO, to draw power from the fuse box feed behind the dash on the passenger side main. Get another nut of the same thread & size to fit atop existing.

Route down towards floor inside panel and use existing opening near grab bar to exit panel.

Go up A-pillar in gap from glass to panel and continue to center. Hidden. Find the way to bring the power into the console (easier for you to figure out versus described here).

In both types, have enough left over to wrap thru ferrite and have it out of the way with enough slack to remove radio with power still attached.


Time for me to get the pre-trip started. I haven’t done Volvo or International, but I’ll assume they’re not terribly different.

Power Reserve
Noise Reduction
Cool Running

It’s insurance to have this out-of-the-way.

If 12V electrical wiring is new to you, consider my experience relayed here a help to the friend or tech assisting you.

This level would be quite expensive to hire someone to do.

Most shops will run a heavier gauge than factory down to fuse box and use a tap to install. That may work with a noise filter like the ferrite shown or other devices.

I’d still insist on Marine Grade plus other as above. (Bring your own).

The Mobile Amateur Radio Installation Bible for ALL details not covered here.
www.k0bg.com

Good luck.

 

[W8HDU]

FWIW, in my Chevy Silverado, I used a Kenwood KLF-2 power filter. Shop around for best price. Mount under dash, take B+ to battery or to accessory (relay) for power. Of the KLF-2 to the radio. Make sure the KLF-2 is grounded and that the chassis of the radio is grounded to the same connection.

If this is your truck, sometime copious amount of braided grounding must be done between body panels, chassis, exhaust, etc. On both the Silverado and F150, noise can develop due to resistance between body components and chassis. For example, between the bed and the cab of the 1500 I measured 5.3-ohm resistance. Scraping off some paint and then bolting some strap to bond both ends solved that as well as took 40-meter noise down 2dB. After making the bonding, clean the connection and then apply body protecting spray.

 

[RFI-EMI-GUY]

All good information for any vehicle.

I have an older Ford Expedition and see the need to bond the hood. I have since had concern that the existing factory ground braids, for battery negative, engine, body and frame should probably be replaced as those wear out and you find various strange problems with the vehicle systems.

I have an ABS concern right now and I know that the radiator support bracket (a large structure), where the ABS gets its ground, needs to be replaced. I bought a new one and it was the last OEM part on earth. I paid as much to ship it to me as I paid, well over $900 in total.

That radiator support having rust is odd for this Central Florida car. I suspect galvanic corrosion between the aluminum hood, radiator, the AC condensor , oil cooler and the steel bracket.

How to prevent this other than protective sealer and paint is a mystery. Perhaps I will put a milliameter across the parts to see where stray current is flowing.

As far as routing cables. I recommend a cheap USB endoscope camera from Amazon that will work with a tablet or laptop. I used mine to inspect inside the A- pillers and windshield pinch weld for rust. It will be equally helpful to aid in seeing where you can run cables in blind areas of the firewall and dash area. I got a very cheap one and it is magical. I might spring for one with better resolution however.

Bonding

 

[slowmover]

Miscellaneous



A couple of additions I’ve used:

1). Here’s a 12V noise filter more ordinary than the KLF one linked two posts up (which I’d rather have). They are directional.

2). Shown with an MFJ RigRunner 4005 12V distribution panel. Adds a little quieting, but maybe not enough to replace a dedicated filter.

— If that condo sleeper has several devices to power in the radio system (mine has five) this is a way to distribute where with the use of Anderson PowerPoles quick disconnect is possible.

However, that system requires fairly expensive supply & tools. If you’re going to be in the same truck several years and don’t plan to swap components, disregard.



3). This is the BATT POS in my pickup. Identical to what I’m using in the Freightliner. A BUSSMAN MBRP Fuse (power cable is thus splice-free).


4). Case Ground

I think of this as a 12V thing even though it’s really an RF concern. I make case grounds to bond any radio gear to the 12V Negative ground. Some, “maybe it will help insurance”.

RF flows on the surface. Thus the use of coax shield from scrapped cable. The more surface area the better. (Wire isn’t a substitute).

This shorty went from radio case to a metal radio carrier bolt. You want these short (8-10”; try not to exceed 12”), and then a wide piece of something (braid or copper sheet) to the actual Negative.

 

[slowmover]

New truck assigned

Got into this truck in January. Maybe you’ll find it a familiar sight that after Orientation with minimal gear before getting a load past the house to get the drivers truck gear aboard, a Fly-n-Drive radio was used:



An 86V and American Mobile CBs most famous example of a West Mountain Radio CLEARSPEECH DSP Speaker atop it. (@CDX951 another truck driver user on this forum).

With cigar lighter power and built-in antenna, this was typical low performance despite high-performing components. Hear, and get heard three miles and one mile, respectively.

Per this thread, the power is the easiest place to start the radio rig upgrade. Done correctly you need not worry about it again.

Take your time.
Acquire best supply.
Follow best practice.

.

 

[slowmover]

A pair of FTL Evos:

Uniden bearcat 980 insane swr.

I'm new to the CB world in that I have very limited knowledge of the numbers side. Anyway, I have a 2022 Freightliner cascadia with the driver side mirror mount. The built in antenna is garbage. I am using the heavy duty stud mount,a wilson 5000 antenna, with a 18ft coax into the uniden 980 ssb...

forums.radioreference.com

A saga of boys and their dogs.

Other big truck radio rig issues in an ongoing thread where power is also addressed.

@Dekgit went from being Sad Sam, to, “hey, this is MUCH better!” (and he hasn’t done everything yet).

.

 

[W8HDU]

Two side stories. First is in our fleet of vehicles I started having issues with lights going out. Found that the ground side of the signal above 1k-ohm or more. Manufacturer cheaped out and decided to use the body as ground, and the various mechanical connections between the tail of the vehicle and battery negative connection, (next to the battery on right fender), was the issue.

Second, in the 80s I was on a team of engineers which were working on problems with AM reception in newer manufactured vehicles. Most of the problems we found were due to the mechanical connection on the ground side of the antenna to the fender which was well above 1,8k-ohm from fender to radio. When it's that high, the radios start picking up noise from the auto's computer and ignition system. Toward the end of the project we found out that one manufacturer (one with the blue oval) was lying to the LMR guys who were fighting the same problem telling them, "the guys in AM broadcast said everything was fine".

Lied to you, there is a third story. In the community I'm in we have a ham who likes to work HF in his car while he travels. He often complained about a popping noise in his reception. Found out that the ground over time on his antenna became resistive due to age and e-coating on the product. However, due to the power he was running, the antenna started to arc in several locations where grounding was weak, causing pitting and even holes in the body.

 

[slowmover]

Coax System is the bigger upgrade needed as the factory system goes thru a multiplexer where the AM/FM/WX share the antenna(s).

— Radio Power is the easier first step (as above) and isn’t going to need a second go-through. Ever.

I met another driver from our company to swap loads. As that truck came off the scale I asked about the weight distribution across the radio.

At 100-yards I could barely hear the driver. You’ll go thru tens of thousands of trucks before you find ears as good as mine.

Stock radio plugged into stock FTL factory system. Sure, the mic gain could’ve been down . . . .



Get a start, drivers.
.

 

[slowmover]

Along with measuring (use clothesline), find the right step-down heat shrink butt connector for both POS & NEG. Shown is an example of 10-AWG to 16-AWG to splice into the radio power cord.

IMO, do the splice close to the radio, but not so close it puts a strain on the harness once radio installed (factory glass fuse not needed with fuse at POS on BATT or at panel feed). Put connector into radio and “turn” a gentle 90-degrees, then under about a foot from turns end, locate splice in.

Just past that is where I wind POS & NEG around the snap-over ferrite in post above.The weight of which should not pull at the radio connector once radio installed. Nor at the step-down splice the subject of this post.

— I use zip ties in the various sizes that, once built and split loom cover installed I run POS & NEG together so far as they’ll go, then keep cover from twisting or moving.

Larger, wider zip ties to attach to various points to keep whole harness stationary (same as a factory truck harness). Isolate weight of ferrite ring assembly.

Details in lay-out + construction pay off.

No strain on splices or terminations once radio installed.

Nor too much length. Slack enough to move radio from installed location to easily disconnect power.

FWIW, I’ve rebuilt power or coax lay-outs more than once. Too long, too short, or wrong routing.

Not perfection, but a thorough plan involving best supply.

Ordering supply online is easiest and sometimes cheapest. H-Freight for zip ties in large quantities as it may 3-4 tries to get things ship-shape & Bristol-fashion.

One wants confidence the company shop looks at your power harness it’s better than what they’d have done. Oversize and overbuilt.

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[slowmover]

Once done ought to look a little something like this. It’ll depend on your radio rigs fused amp draw, total circuit length (POS + NEG) and the terminations needed to attach to battery post or fuse panel feed.

This one is with an MBRF fuse to go to the Battery Box, and a POWERWERX Anderson Power Pole distribution block as (5) devices need power.

 

[iMONITOR]

In Post #5, that battery connection needs a serious cleaning!

 

[slowmover]

In Post #5, that battery connection needs a serious cleaning!

View attachment 144340

Ha!

No, what it needs is the installation of an entirely new cable system to replace the 20-yr old OEM.

C-E Auto Electric Supply

Gen 3 Dodge Ram

My pickup mainly sits. And needs more besides. But the radio system has adequate power per amp draw & volt drop.

On a big truck it’s multiple batteries. Attention should be paid per above post.

Thx

.

 

[W8HDU]

Replacing with new cables, waterproofing, and corrosion proofing is important. Also, bring one cable, fused, off the battery and to a breakout system, isolating each circuit to a separate fuse and cable to each radio. In my work truck I come off the high current battery stud (fused at 100A) to a PowerWerks (4) fuse breakout which feeds each radio, (LB work radio, HB Itinerant, Ham/FT857D, and CB). I also used "Cool Amp" on the lugs before attaching, and then protect them from the elements. Road salt is the worse up here in the north. When installing, be aware of stress points and possible wear points such as firewall penetrations and things that move, (cables, hoses, steering shaft, etc.).

Grounding is imporant as well. I run the power ground next to the B+ and take it back to the battery ground.

Don't depend on metal to metal bonds, especially those which show signs of tarnish, or pitting.

Finally, one thing I learned from a local radio shop, most trucks and cars, post 2002 have a moderate amount of e-coating or plating on between body panels, chassis, ect. You can't depend on it for a ground. In a M2 106 Plus Freightliner we found 1.62-ohm resistance between the dash support, and the B- on the battery. This small differential caused S9 of "hash" on the radio (up to 152 MHz), since there was zero shielding for all the computer and truck noise. Once the grounds were corrected and unified, no noise. Just about every body panel needed a strap and new ground. Cab to chassis was worse.

 

[slowmover]

Replacing with new cables, waterproofing, and corrosion proofing is important. Also, bring one cable, fused, off the battery and to a breakout system, isolating each circuit to a separate fuse and cable to each radio. In my work truck I come off the high current battery stud (fused at 100A) to a PowerWerks (4) fuse breakout which feeds each radio, (LB work radio, HB Itinerant, Ham/FT857D, and CB). I also used "Cool Amp" on the lugs before attaching, and then protect them from the elements. Road salt is the worse up here in the north. When installing, be aware of stress points and possible wear points such as firewall penetrations and things that move, (cables, hoses, steering shaft, etc.).

Grounding is imporant as well. I run the power ground next to the B+ and take it back to the battery ground.

Don't depend on metal to metal bonds, especially those which show signs of tarnish, or pitting.

Finally, one thing I learned from a local radio shop, most trucks and cars, post 2002 have a moderate amount of e-coating or plating on between body panels, chassis, ect. You can't depend on it for a ground. In a M2 106 Plus Freightliner we found 1.62-ohm resistance between the dash support, and the B- on the battery. This small differential caused S9 of "hash" on the radio (up to 152 MHz), since there was zero shielding for all the computer and truck noise. Once the grounds were corrected and unified, no noise. Just about every body panel needed a strap and new ground. Cab to chassis was worse.

Thanks for these thread additions, this one and the earlier.

 

[W8HDU]

Thanks for these thread additions, this one and the earlier.

Thanks, Slowmover. It's been unfortunate that the newer trucks and cars have more noise than your run of the mill 1970s VW. Too much electronics in the vehicle which is not properly grounded. I will say if you have done the due diligence on the grounding, adding a Kenwood KLF-2 power filter to the radio which has the most whine helps, but proper bonding and grounding is the secret. I notice they have come down in price on the used markets, to around $14 to $20.

 

[slowmover]

For more on the KLF-2 ($50 new, approx)

1). Cover removed.
2). DIY (link)

San Antonio Hams

Local info about Amateur, Ham, Radio in the San Antonio, TX metro-area. We've got nearly 20 clubs/groups listed.

sanantoniohams.org

For the truck driver wondering, “why?”, getting the NEG to shortest (think “inches”, not “feet”) may present its own difficulties for dead quiet DC power.

Test for noise (is the point). Try solutions.

This is one of those.

Big trucks are quiet till they ain’t (inverter in use, etc). Most noise comes across coax. IMO, leave no route for it thru DC power as it complicates diagnosis.

Re the first post: The test is while underway.

Before the fancy radio. Before the expensive antenna, mount, bonds, etc. Before all else get DC out of the way.

.

 

[W8HDU]

Amazing what the KLF-2 costs and what it's comprised of. But then, try building one and sourcing the parts and labor and $15- $50 seems very reasonable for a used one. With the exception of the electrolytic, there is not a lot to go bad.

 

[slowmover]

Whether I’m using the DX-959b shown or an integrated NRC Q5 for the passenger seat radio station, I’ve the room for dividing up the 12V several times. Room for that KLF going into a RigRunner 4005.

There’ll be a A-B test of radios (959 further modified vs Q5) with a coax switch in the future. Best to tamp down 12V noise.

.

 

[slowmover]

Forgot to add:

I can operate the radio in the Freightliner on a quiet channel (nothing heard), and can hear alternator whine with volume turned up.

This is at same level when at highway speed and window cracked open.

Faint, but present. (Would be “louder” in a typical private vehicle; more noticeable).

KENWOOD KLF-2 Line Filter Instruction Manual

KENWOOD KLF-2 Line Filter Instruction Manual

manualspro.net

I haven’t spared expense with the power harness otherwise. If I liken it to using a coax filter in the antenna system, the expense has a proper category.

— Chasing after Clarity in the terrible operating conditions midday and later during periods of heavy Skip operating mobile on AM-19 and trying to keep local comms alive to greatest extent (fits marginal gains in antenna or power systems device expense).


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