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Electronic noise elimination...


Gregori

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As I prepare to install my Autocom, I'd like to solve the noise issues BEFORE I put it together.

 

I'll have the Autocom, with V1, GPS, Police scanner and iPod, all bike powered.

(Plus a Kenwood XLS FRS/GMRS which will be battery powered.)

 

I've got a couple of isolated audio leads (for GPS and V1) as well as the Autocom 'Part 57' which is a 2-into-1 mono mixer that's supposed to be isolated.

 

Has anyone tried running power with Cat-5 cable? The twisted pairs should eliminate any noise/interference. At 24 gauge, it's good for less than 4 amps (per pair) at the voltage and distance we'd be working with. That should be plenty for GPS, V1, Scanner and iPod power supplies, as each have a 1 or 2 amp fuse already. I'm not sure how much power the Autocom draws...

 

Thanks!

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The Autocom draws less than 1/2-amp, unless you're also using it to power a Kenwood TK-3131 (Kenwood XL) FRS/GMRS radio, which can draw up to 2 amps.

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I was PMed some info which may help others, so I've included the pertinent parts of it (and my responses) here:

 

>>Which Autocom have you got?

- Pro-7. And based on the info in the PDF link you sent, I have a part 56, not 57.

 

>>1) What is the most dispensible source - usually music.

- Music and GPS. (I also have a Sean Daly 3-into-1 mono/stereo mixer, but neglected to mention it in my first post.)

 

>>2) What priority do the other sources take. Do you want the V1 to mute the GPS or the other way around.

- the V1 and Scanner, which are my ECM (Electronic Counter Measures) would be top priority, and I figured I'd run both of them (mono) through the part 56 to the Aux 2. to pre-empt the GPS/iPod (in Aux 1) as needed. I am NOT sure if Part 57 has a pre-empt channel internally, or if it's strictly a mixer.

 

>>3) You do not have to feed expensive isolated audio cables into an isolated part 57 splitter. Two lots of isolation will may cause volume to be reduced. Usually if you have an twin isolated splitter you can use cheap 2.5mm mono to 3.5mm stereo cables part 1561 (old part 171) to feed into the splitter.

- I haven't figured out all the wiring, though I expect that I'll have to get or make 2.5mm to 3.5mm adapters, or buy new isolated cables.

 

>>This link to the Autocom website may help: http://www.autocom.co.uk/pdf/56-57-58.pdf

- Thanks for that. I have a bunch of Autocom PDFs already, but that wasn't in in there.

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The reason I could not reply to the board was down to a glitch on my computer

I was PMed some info which may help others, so I've included the pertinent parts of it (and my responses) here:

 

>>Which Autocom have you got?

- Pro-7. And based on the info in the PDF link you sent, I have a part 56, not 57.

Good, as part 57 is intended for one cellphone input

>>1) What is the most dispensible source - usually music.

- Music and GPS. (I also have a Sean Daly 3-into-1 mono/stereo mixer, but neglected to mention it in my first post.)

 

>>2) What priority do the other sources take. Do you want the V1 to mute the GPS or the other way around.

- the V1 and Scanner, which are my ECM (Electronic Counter Measures) would be top priority, and I figured I'd run both of them (mono) through the part 56 to the Aux 2. to pre-empt the GPS/iPod (in Aux 1) as needed. That sounds correct. I am NOT sure if Part 57 has a pre-empt channel internally, or if it's strictly a mixer.

Parts 56, 57 & 58 are isolated mixers - no preference is given.

 

>>3) You do not have to feed expensive isolated audio cables into an isolated part 57 splitter. Two lots of isolation will may cause volume to be reduced. Usually if you have an twin isolated splitter you can use cheap 2.5mm mono to 3.5mm stereo cables part 1561 (old part 171) to feed into the splitter.

- I haven't figured out all the wiring, though I expect that I'll have to get or make 2.5mm to 3.5mm adapters, or buy new isolated cables.

If you look at the pdf, you will see that the cables into the isolation blocks are, variously, part 50, 170 & 171 - none of the them have isolators in them. They are easy to buy or make.

 

>>This link to the Autocom website may help: http://www.autocom.co.uk/pdf/56-57-58.pdf

- Thanks for that. I have a bunch of Autocom PDFs already, but that wasn't in in there.

 

Your Pro M-7 was a top of the range model having the large heat sink capable of bike-powering a suitable FRS radio. It has been superceded in this respect by the Super Pro AVi. The other new models, Kit 150 and Kit 200, should not be used for this purpose.

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