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Old July 28th 06, 06:30 AM posted to rec.radio.cb
SparkySKO SparkySKO is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 28
Default Noiseblocker vs Fuel Pump Results

So my results with a Cobra 75 with just soundtracker had negligible
results versus my fuel pump noise. So I went and bought a Cobra 29 with
ANL, Noiseblocker and SoundTracker. With a base noise of S0 and S3 when
I start my truck, with ANL, Noiseblocker and ST turned on, the noise
dropped from S3 to S2. Although the volume of even voices sounds a
little muted, so the signal to noise ratio was improved a little, but
not completely.

Previously, I had blower motor noise from my AC, which went away when I
bolted an antenna mount onto my fender (When I was using the Midland
1001, Uniden 510, Cobra 75). However with the Cobra 29, the noise came
back. All the radios have used the same antenna mount and wiring
(straight to the battery, also have tried the bare metal where my
transmission shifter comes up from the floor, i'm able to use this for
a DC ground).

I tied of a wire to bare metal (confirmed it's a DC ground) and touched
all of the screws on the radio, no change. If I touched it to the
faceplate for some reason it sometimes changes the noise a little bit
sometimes, but not much. I've also touched this wire to the ground on
the antenna cable, and also tried grounding the antenna mount again. No
change.

Interesting to note that although the S meter drops with NB on, the
squelch setting seems to want to be in the same spot.

Also interesting to note, my portable shortwave radio which can do CB
frequencies, does NOT pick up the blower motor or the fan noise however
it DOES pick up the spark plug noise.

RF or not RF.!?!?!

I did check my fuel tank, and it is metal (I thought it was plastic). I
wonder if this can made to act like a faraday cage? I work in a
wireless labratory with UHF (2.4ghz, unfortunately nobody else is
really radio savvy, especially with HF), and we have rooms made out of
copper screen that is electrified ( i believe ), and no RF comes in or
out. Of course all the powerlines also need to be filtered.

Although I guess if the noise is coming out from the wires, it won't
make any difference.

I'm going to probably return this Cobra and get the Midland 1001Z again.