102” whip shipping

[Slowmover]

My truck had symptoms of common mode current with short coax. I “hid” the symptoms with longer coax until adding ferrite to the feed point (under puck mount).

This was the first time I ever ran into this - I had always cut the coax to the length needed, which was universally less than 18’.

If I could do the install over again I would use a precisely measured 1/4 wave length of coax to make use of a analyzer more practical. But, I’d also plan on a feedpoint choke from the get-go. In truth, all over my head...trying to learn tidbit by tidbit via experience and picking brains here.



Mine does not.

18’ feet seems silly.

Unless you decide to make a few toroid chokes.



Each arm of the co-phase harness is 18’
IIRC, it’s nine turns with a 2.5” diameter circle.

Entry and Exit are kept separate. Coax doesn’t overlap (ideally). Spaced along the FT-31-240 toroid one after another.

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[Slowmover]

Does the Hustler 102" have any adjustment set screws in the base like the Workman model? Is there any model better than the other? Was wondering for my little Ford Escape and a quarter panel ball mount?

I like the idea of adjustment if needed.

And to push the old wives tail. What if I run 12' or 9' or coax and not 18?

The electronic highway billboards in PA are looking for an escaped senior in a Ford Escape.

Need that 102” and tinfoil cap.

 

[2NC995]

He picked the right car.

 

[Highway Man]

I would just use 18' of a premium super mini 8 and be done with it. Otherwise, tune at feed point and don't rely on a SWR meter

 

[Cutlass327]

18’ feet seems silly.

Unless you decide to make a few toroid chokes.

View attachment 38203

Each arm of the co-phase harness is 18’
IIRC, it’s nine turns with a 2.5” diameter circle.

Entry and Exit are kept separate. Coax doesn’t overlap (ideally). Spaced along the FT-31-240 toroid one after another.

.

What is that choke setup meant to "remove"?

I am wanting to eliminate RFI from the ECU and fuel pump from a Ford powertrain...

 

[2NC995]

What is that choke setup meant to "remove"?

I am wanting to eliminate RFI from the ECU and fuel pump from a Ford powertrain...

Cutlass,

I put 5 - 1/2” split bead ferrites on my feedline right at the antenna mount and noticed a significant reduction in noise from the vehicle.

My plan in doing so was addressing common mode currents...I didn’t even know that noise reduction might be additional benefit.

Anyway, I can’t explain the how or why (maybe someone can) so I’m just enjoying the newfound quiet.

 

[Highway Man]

Ground ground ground, the big 3. You can YouTube that. Also ground the hood. Maybe get better shielding coax. This site has a section on fuel pump noise and chokes

http://www.k0bg.com

 

[Slowmover]

What is that choke setup meant to "remove"?

I am wanting to eliminate RFI from the ECU and fuel pump from a Ford powertrain...

I’ve spent much too much time at:

www.palomar-engineers.com

and have spent a good bit there. No disappointments, but it can take awhile both to navigate AND to use the site for learning. Different routes thru the maze brings different results. See tech papers, etc.

See WWDX for the thread, MOBILE COAX CHOKE

A comment by “Doc” a few eons back this site had the approximate quote, “getcha a five-gallon bucket of toroids, and get to work”

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[Cutlass327]

"5 gallon bucket of toroids.."

If only I had a grand to spend on them! Those things aren't cheap for the good ones.

I have some of those snap-on beads, maybe I'll see what happens there. Also a couple snap-on ring style.

As for coax type, I'm not sure what brand it is any more - some I found around here and put it on, may even be Diesel brand from the T/A. I have some 8x from DXE to replace it with, as I want to re-route it, too. Right now I believe part of the issue is it is parallel with the power wires to the fuel pump along the frame. I plan to run it down the other side to get it as far away as I can.

 

[Highway Man]

I've run KWs in a mobile and never used a toroid.

 

[Slowmover]

I've run KWs in a mobile and never used a toroid.

Never used, or never tried?

Statement by Applegate is that CMC problems exist in every mobile install, only a matter of degree.

Point is, it’s cheap as an experiment.

A five-gallon bucketful, though, is flat funny.

“Doc” may have been also the one to say (on the question of how many RF Bond straps are enough for mobile),

“Get underneath and start measuring, cutting, crimping, drilling, screwing, shrinking and soldering. And when you’ve gotten tired, that’s enough”.

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[Cutlass327]

Well, hard to bond a soft top, fiberglass body, fenders, and windshield frame. Only the hood, grille, and dash is original metal. I have considered a strap from the hood to battery ground though. Grille is already grounded electrically. Roll bar is bolted to frame, but with rubber bushings between, so maybe I'll strap it too.

 

[Slowmover]

Well, hard to bond a soft top, fiberglass body, fenders, and windshield frame. Only the hood, grille, and dash is original metal. I have considered a strap from the hood to battery ground though. Grille is already grounded electrically. Roll bar is bolted to frame, but with rubber bushings between, so maybe I'll strap it too.

My impression is that too many is a possibility.

See M0GVZ comments at current thread end of HIGH SWR thread.

(I surrendered, Time to buy books).

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[Highway Man]

Never tried. Just didn't know at the time. Whenever the mic would zap the pi$$ out of my lip or keying up flipped the computer i knew it was time to get the wire wheel out and polish up the grounds.