Proper mobile hardwire

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skatertj

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I have a pro-2055. Not the greatest scanner, but when i got it, i only paid 30 for it and it was like BRAND NEW! I currently have it hardwired into my car. The antenna i have now, i just got and its a larsen NMOQB 1/4 vhf and with a NMO permanent roof mount(NMOKHFUD). During the time i waited for the antenna to arrive, i kept my scanner in my upstairs room with the stock telescopic antenna. It picked things up GREAT! Hardly ever any static or hiss. After i put it back in car(had in before with a old mag mount RS antenna), the scanner receives some frequencies with static and hissing. I figured with the nicer cable and good antenna, i would receive all the signals that i got in the house, the same or better while its in the car.

Im curious to know if my antenna cable runs of power wires, if that can cause the static or hiss? The cable it double insulated.

Or should i find new power and ground points for the scanner? Currently grounded to random screw under dash and forgot power source.

Thanks!
 

mmckenna

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Automotive electrical noise can cause a lot of issues. Tapping into any old 12 volt source you find can lead to issues, especially if the circuit is shared with something like the cars computer, blower fan, etc. Getting a nice clean power source is best. An easy way to narrow down the cause of the noise would be to check and see if it is there when the car is running, with just the ignition on (not running) or with the car off.
Running the antenna cable near noisy circuits can cause issues. I think you meant to say Double Shield, not double insulated. Double shield is what I always use.

Could also be a bad connection at the antenna/NMO connector. Check to be sure that the center pin/pad of the mount isn't touching the outer ring. Doing that can create a short circuit to ground and you will loose a lot of your signal. One easy way to do that is to remove the antenna and use a 1 or 2 foot piece of wire or coat hanger and touch it to the center pin of the antenna mount. If the signal improves, it's likely an issue with the mount/antenna interface. NMO-HF mounts are good, but can sometimes cause issues with certain types of mounts. Shouldn't be an issue if you are using all the same brand stuff.
Another thing to try is to remove the antenna, and disconnect the coaxial cable from the back of your scanner. Use a multi-meter to check for continuity from end to end on the center conductor and for the outer shield. Also check to be sure there isn't a short between the center conductor and shield. An issue there will certainly give you trouble.
 

skatertj

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If im correct, my signal improves with the car off. The scanner is hooked to a continuous power source. I am driving a ex cop crown vic so i have plenty of power sources to try. I think i will put my AC power cord to the scanner with it still in the car and hooked to the larsen antenna to see if the signal is fine. If so, i know its power interference.
 

WA0CBW

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As mmckenna indicated check your NMO mount and antenna mating connector. Not all NMO mounts are the same. There are slight differences between manufacturers on the height and diameter of the center pin stud. Same goes with the antenna pin that contacts that center pin stud on the mount. It is best to stay with the same manufacturer for both. Also keep the power and antenna leads as far away from the cars electrical/electronic wiring as possible.

BB
 

skatertj

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mmckenna

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Using attenuation(think thats right) makes the fuzziness go away abit. Does this mean something? I will probably rewire the power to the battery and reroute the antenna cable once i get a warmer day.
That likely means you are getting noise in from your antenna/feedline. Reroute your coaxial cable and that may just fix it.

Before you tear everything apart, start with the easy stuff. Leave the radio hooked up and running if you can. Try moving the coaxial cable around under the dash and see if things improve. Might just be a simple fix.
 
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