The CBRT/TWRC Convention
July 28 & 29, 2017

humm noise cobra 25ltd classic

This is the place to post your general tips, or need to have a question on your install here.

Moderator: JR Moderator

User avatar
p38
Skipshooter
Skipshooter
Posts: 280
Joined: Friday, 07 December 2012, 16:43 PM
Radio: magnums9 /madison
Antenna: 102 whip
Name: Jonathan card
Cell Phone: 4012062673

humm noise cobra 25ltd classic

Post by p38 » Friday, 01 February 2013, 20:28 PM

if my rf gain is turned up too much i get a humm/buzz noise tfrom my radio?!? even with the noise blanker on sometimes. can anyone explain this?
Jack of all trades ,master of none

ASE certified technician

my radios -cobra 25ltd /cobra 29ltdX2 /trc-501 / 1977 president madison am-usb-lsb/ magnum deltaforce 10meter /stryker 955hp magnums9 . imax 2000/ 102whip /k40 mag mount aracher crossbow 3 element on the flat side.




User avatar
231
Site Admin
Site Admin
Posts: 7205
Joined: Friday, 13 January 2006, 15:19 PM
Radio: Uniden/Icom/Cobra
Location: Trudging the Pacific NW Trail
Referrals: 1

Re: humm noise cobra 25ltd classic

Post by 231 » Friday, 01 February 2013, 23:23 PM

Maybe...
- Is it mobile mounted?
- Where do you have the power leads coming from (i.e. both +/- directly to the battery)
- If it's base mounted, what are you using for a power supply?

There will be more questions...but it's impossible for anyone to say with the limited info' you've provided. It could be anything from an electrical device(s) from from your neighbors to a problem with the power source, and everything in between. More info' will help us determine where to start looking first.

Good luck.

231

User avatar
p38
Skipshooter
Skipshooter
Posts: 280
Joined: Friday, 07 December 2012, 16:43 PM
Radio: magnums9 /madison
Antenna: 102 whip
Name: Jonathan card
Cell Phone: 4012062673

Re: humm noise cobra 25ltd classic

Post by p38 » Saturday, 02 February 2013, 20:32 PM

yes it is in my mobile a 1998 blazer 4 door. i have the power direct to the battery with a noise filter xterminator 250 watt 15 amp . 102 whip with a quick disconnect k4a stud on a steel plate mounted too my bumper which is steel all the connections are good the antenna I the stock have a power mic as well.
Image
Jack of all trades ,master of none

ASE certified technician

my radios -cobra 25ltd /cobra 29ltdX2 /trc-501 / 1977 president madison am-usb-lsb/ magnum deltaforce 10meter /stryker 955hp magnums9 . imax 2000/ 102whip /k40 mag mount aracher crossbow 3 element on the flat side.



User avatar
231
Site Admin
Site Admin
Posts: 7205
Joined: Friday, 13 January 2006, 15:19 PM
Radio: Uniden/Icom/Cobra
Location: Trudging the Pacific NW Trail
Referrals: 1

Re: humm noise cobra 25ltd classic

Post by 231 » Sunday, 03 February 2013, 11:14 AM

Make sure you aren't parked under (or next to) a power line, house, or anything else where noise can be generated.

The antenna may be picking up fuel pump noise being the rear bumper isn't the best place to locate the antenna. Not an uncommon problem when antennas are located there either. With the radio on and engine running remove the antenna and see if the noise goes away (or at least seriously cut down). If it does, there (most likely) lay your problem. Half the battle is identifying where the problem is and where the noise is getting into the radio from.

Honestly, options may be to relocate the antenna (my first choice). A good heavy duty fender mount will not only improve your performance, but likely remove the noise if in fact it's fuel pump causing it. The other option is to find the power leads to the fuel pump and run run ferrite cores on it, maybe even adding a capacitor. That's what I had to do with my diesel pick up after being left no option but a performance upgrade when my fuel pump failed. It caused all kinds of racket on my Icom IC-7000 which has some of the best filtering available in it. The ferrites and capacitor solved the problem though and no additional filtering was required. But on an OEM submersed fuel pump (like you probably have) it can be a pain to do. Relocating the antenna is almost always easier (not to mention will work better). Just may not look as good.

Just a few thoughts. Good luck.

User avatar
str8stroke
Donor
Donor
Posts: 953
Joined: Friday, 30 April 2010, 13:49 PM
Radio: Gold Cobra 29LTD
Antenna: 1/16 Wave Dipole
Name: Ric Flair
Home Phone: 27.235.000
Cell Phone: 8007597243
Location: Da Bayou

Re: humm noise cobra 25ltd classic

Post by str8stroke » Monday, 18 February 2013, 4:30 AM

Could be a short in the mic cable? That can make some gosh awful noises.
Ric Flair is on the Air, with Pink Underwear!!! WHAOOO!!!




User avatar
Z-MAN
Duckplucker
Duckplucker
Posts: 186
Joined: Friday, 01 February 2013, 4:41 AM
Radio: RCI 2990, 98VHP
Antenna: Sirio Tornado
Name: Rob

Re: humm noise cobra 25ltd classic

Post by Z-MAN » Monday, 18 February 2013, 5:10 AM

Good call on the Fuel pump but i would shorten the ground wire to the chasis. Just like with Car stereo amps, so there's no noise, if nothing works maybe turn the recieve down in the radio? Could be too high?
Z-ROCK! Z-ROLL!



User avatar
p38
Skipshooter
Skipshooter
Posts: 280
Joined: Friday, 07 December 2012, 16:43 PM
Radio: magnums9 /madison
Antenna: 102 whip
Name: Jonathan card
Cell Phone: 4012062673

Re: humm noise cobra 25ltd classic

Post by p38 » Tuesday, 05 March 2013, 21:34 PM

Z man thats what is was thinking! Some.one.has been inside it before . It has a short ground strap and its mounted too a steel bumper with the pain ground.off ! Only hear it once and awhile now on both of my radios! The other one is a 29ltd turned up past mudd duck power :lol:
Jack of all trades ,master of none

ASE certified technician

my radios -cobra 25ltd /cobra 29ltdX2 /trc-501 / 1977 president madison am-usb-lsb/ magnum deltaforce 10meter /stryker 955hp magnums9 . imax 2000/ 102whip /k40 mag mount aracher crossbow 3 element on the flat side.



User avatar
721HACKSAW
Donor
Donor
Posts: 1566
Joined: Monday, 25 February 2008, 10:43 AM

Re: humm noise cobra 25ltd classic

Post by 721HACKSAW » Wednesday, 06 March 2013, 4:08 AM

Does the noise go away when you turn the vehicle off? Does it go away when you disconnect the coax? We need to narrow things down to determine if the noise is external and how its entering the radio.

User avatar
p38
Skipshooter
Skipshooter
Posts: 280
Joined: Friday, 07 December 2012, 16:43 PM
Radio: magnums9 /madison
Antenna: 102 whip
Name: Jonathan card
Cell Phone: 4012062673

Re: humm noise cobra 25ltd classic

Post by p38 » Saturday, 09 March 2013, 17:41 PM

Truck on or off no difference. When its running it humms if the nb is off.
Jack of all trades ,master of none

ASE certified technician

my radios -cobra 25ltd /cobra 29ltdX2 /trc-501 / 1977 president madison am-usb-lsb/ magnum deltaforce 10meter /stryker 955hp magnums9 . imax 2000/ 102whip /k40 mag mount aracher crossbow 3 element on the flat side.




Post Reply Previous topicNext topic

Who is online

Users browsing this forum: No registered users and 1 guest