Using chokes in Cascadia??

Don't know where you live, but most Ham radio stores offer a few different styles of snap on chokes, or order direct:
http://www.mfjenterprises.com/Product.php?productid=MFJ-700A
That is just one of many styles they offer.

But my experience with these has been that they are better at keeping noise out of the receiving lines for a radio, than protecting the other electronics around the radio. It sounds like you have a shielding problem with the design of the truck vs. however much power you are running.

 

Something aint right here,that 98 doesnt put out much over 200watts if that ?I think it run eight mosfets ?
Your gauge cluster runs off its own ECM which is free of the mirror heat which is wired direct(You have at least 7 ECM's on that truck)

Where are you running the hot line from ?
Where did you ground out at ?
What size is your power wires ? at least 12ga I hope

Where is the radio mounted ?

FWIW,you will never get all the noise out of it,a good bit is coming in on receive and nothing to do with the radio or how its hooked up.

 

Bullit,
Yup's questions are good ones, and those of us who do this stuff for a living would benefit from their answers.
Also, do you have a decent dummy load you can hook to your radio in place of its antenna? If so, meter the DC voltage *at the radio's connector* when you transmit. That'll let us know if your wiring is skookum enough for the load.
Also, see how many of your gauges and such do their reported silliness compared to when the antenna is there. Several things can cause your transmitted RF (the "radio frequency" signal) to get into your vehicle's wiring and indicators.
Any electric motors that cause noise in your receiver can be bypassed right at those motors with appropriate capacitors. Any noises that you're used to hearing in your receiver that stop happening with the antenna replaced by a dummy load are being transmitted through the air, and will have to be eliminated at their sources. Wiper motors, fuel pumps, window motors and the like are good examples.
If your power and/or DC ground wiring have too much resistance in them, the battery's ability to filter DC-line-borne noises out before they get to the radio.

It sounds like you've got a couple of things going wrong there. If your radio has been "tweaked and peaked" for maximum output but without benefit of a spectrum analyzer, and if you're not running with a low pass filter between the radio and the antenna, then any harmonics your radio is transmitting will likely *not* be radiated through the antenna, and will spray around in the cab from the outside of the coax line.

As Yup suggested, there are several things that can contribute to what you're describing. Is *everything* is identical to the way is was with the Stryker, then it's worth having a "real shop" put your Galaxy on the bench and check for faulty work done in the past.

All I've got for now, until you're able to answer some of the above-listed questions.

Hope this helps,
-- Handlebar --

 

Yep, lets clip that modulation limiter and crank it all wide open LOL

Sounds like the "whack-packers" have been at it again...

 

Handlebar is right on the money, a good friend of mine had the pleasure of moving into a cascadia and told me of the same problem. If I were you i'd start with the dummy load and then move right to the antennas, the coax they use is JUNK with several motorola plugs to join them. In my friends truck we swapped out the coax and ran ground leads down off the mounts (to give the antenna some metal to work off) the coax swap seemed to do the job. GOOD LUCK !!

 

Not to mention that the am/fm splitter box is not designed to handle 200 watts...

 

Ah, I forgot that truck has the antenna multiplexer. And, as Delta5 noted, the coupling/filter box is made for low power only.
If you get a low pass filter, put it after the last device inline with your antenna line (after the amp, if there is one) and see if a wattmeter *after* the filter shows differently than when the filter isn't inline.
If you're going to run power, regardless of the antenna you use, it's good practice to have the low pass filter inline all the time, so that any out-of-band signals your system produces aren't transmitted by your antenna. But it's also a good test tool, as noted above. And if the filter *does* make a difference in your power when you put the filter after the radio and *before* the amp, take/send your radio back to the shop that "tuned" it and insist they do it with a spectrum analyzer, and tell them your results with the filter.
If they don't have a spectrum analyzer, you might think of looking for a different shop. These days, when customers are demanding every last fraction of a watt out of their radios, a lot of "techs" are twisting every adjustment they can find to show the customer how good a job they're doing, regardless of whether the power is all in the 11 Meter band or not.
-- Handlebar --

 

Our radio shack sells things like that back where they keep fuses and project boxes, someone here posted a design to build your own noise filter but i can;t remember where i saw it.