power line noise

Yup those will work. (Transformer based Ground Loop isolators)

I used to have a multi-radio headset adapter.. That's how I built it. combined both Ham and CB into one headset... Worked great.

one of the links in my previous post is a ground loop isolator with transformers in it to break the ground loop. here is the manual for it 3.5 Noise Filter he can move it from vehicle to vehicle also.

Well as I said no filter will stop a ground loop. Only a isolaiton device (Transformer) and good transformers are hard to find... Though they do make 'em.

Yes a smaller rechargable battery will work too and is much smaller than my Jump Pack.. I have the Jump pack for..... other reasons.

power the phone off one of those luggable "Jump Start" packs,

I've got one of those, more junk to trip over sitting next to the drivers seat. I've also got a couple of Anker power packs which are the size of a pack of cigarettes that would work as well. Just trying to eliminate the amount of junk around the drivers area. **** phone clamp blocks view of the stereo, then fell off while driving.
I might try one of the dc line filters if I feel ambitious enough to pull the dashboard apart, it's a PIA, but doable if I feel like it. I also found the audio line filter, but supposedly it messes with the sound quality. There's also a cigarette plug adaptor with a built in filter, but it's like $45 and more **** hanging off the dashboard.

As I have said. I HAVE that problem when using LINE IN and my phone.. On my car (Which is older) I use a cassette adapter for line in, and since that IS a transformer, NO GROUND LOOP. The problem is a ground loop.

You need to break the loop, easiest way if you do not have an inverter is to power the phone off one of those luggable "Jump Start" packs, Mine is a 900 Amp job from Auto-Zone.. OH, it also is big enough to fire up the Generator should ALL the batteries run down.. (Did it once so far).

DC whine that changes with engine rev. comes from your alternator on the engine through the power line. one of these in the line to cigarette lighter plug should cure that unless you here it without the phone hooked up In-line noise suppression filter or one of these ground loop isolators may be needed. 3.5 Noise Filter the ac noise on the tv is likely coming from some thing hooked up to it ( sat. receiver,dvd player etc.) unplug them one at a time and see when it quits. if it does it when only a antenna and receiving over the air tv channel then some thing is wrong with the tv probably bad capacitors inside.

What you have with the phone and dash is called a "Ground Loop" Alas so long as you are DC all the way there is no easy way around it.

What I do is power the phone using an inverter and wall wart.. The transformer in the wall wart breaks the loop.

YOu can also get isolation transformers for the audio line but not many of them are ones I'd recommend (Heil Sound makes a good one) But when you go this route impedeance can be an issue

Better choice.. Connect via Blue Tooth or.. Charge up an aux battery (I have some good ones) and use it to power the phone..

ONe thing EVERY RVer needs is one of those portable 12 volt Jump Starters. at least 700 Amps peak.. Use the 12 volt outlet on it to power the phone.