AM Radio Hash

[jacq]

Hello all.

I just recently purchased a Ranger and am for the most part very happy with it.

I am having problems with AM Radio Hash and I dont know where to actually start.

Some symptoms:
Truck not running AM on AM fine (obviously)
Truck running FM ok but AM is really bad

BUT
When I step even lightly on the breaks to at least get the break lights to light up the hash gets less not much but it does get lesser...

This the stock radio
It is a 2000 sport 4 cly manual

I am a big AM listener so this is a problem.

Would anybody be able to point me in some avenues I can take to rectify this..

Thank you very much

Jacq..

 

[RobbieD]

First check that the antenna is tightly mounted. I don't know the newer trucks; you got a metal hood on that thing?

 

[jacq]

Yes I believe I have a metal hood..

Tnx for the reply.. Im a big AM radio listener and this is just annoying.

 

[RobbieD]

I listen to AM a lot, too, so I can sympathize. The antenna is more critical for AM reception. I don't know if your 2000 model used the same antenna design as the earlier trucks, but if so there's a trim cap over the base that can be pried up to reveal mounting screws. If these are loose, tighten 'em up; the antenna being ungrounded at it's mount location can induce radio noise. If you hood is metal, you might also want to add a braided ground strap between the hood and firewall. Basically, the hood acts as a shield for the radio frequency interference (RFI) from everything in the engine bay from getting at the antenna. If it's not grounded well a lot of RFI can get to the antenna, which affects AM reception. Good luck with it.

 

[jacq]

More Data

First RobbieD tnx for the great advice!!
I will try the trim cap removal and check the screws..

Here is what I found last night. I was not going to do much but you got me inspired, and maybe I just got to the point of frustration to try something..

Anyway...
These are the steps I did and the /// results

While the truck was running and radio on 610 or 810 the ones I listen to most here in KS:

1 put alligator clips on antenna and touched the other side to metal hood /// no change.

2 put longer clips on and tried to touch a ground spot in the engine compartment /// no change

3 Tested the "RobbieD is it loose" problem, so I grabbed the ant abt mid way up and gentle wiggled it.. /// it was solid and tight
BUT!!!!
BUT!!!!
When I did that my hand caused some "something" ( and being a ham and having a ham father I should know this.. arg) maybe the word is capacitance. Well whatever it is the signal got better... Hmm..

Ok well I read this on my searchings yesterday:
from this site
http://www.bellscb.com/products/accessories/DC_Noise_filter.htm

If you have radio noise caused by your engine (noise that increases or decreases with engine speed) this filter might help you.

Engine noise can enter your radio TWO ways. Through the power wire source and through the antenna. This filter will reduce the noise coming in the power wire.

To be sure this filter can help you, unplug the antenna from your radio and start the vehicle and rev the motor. Turn up the volume on radio and try to see if the noise went away, or at least most of it did. If the noise stays with no antenna connected this filter WILL help you allot. If the nose goes away after removing the antenna, than this filter will NOT help you. In this case you will need to filter the noise source (like the alternator or fuel pump).

Well kr@p I hope it not the antenna....

I gently open full the glove compartment and find the antenna run.
I reach as close as i can to the antenna under the dash and wiggle. /// no change

I found some colored "wires" and think abt pulling them why I dont know....Well they didnt quite go to the correct spot on the stack...
OPPS they are the AC/HEATER tubes... DOH! Whew gud thing I was slow abt jumping in...

Did not find the radio connector as I know I would not due to the dash construction....
Ok well since I am out here dorking around I might as well pull the radio stack.

Looking around the stack wondering how I am ever going to pull this without tearing it all apart and making it look awful when I put I back together I found 2 screws under the lip of the CD player I think
Took the 2 screws out. Ok so far so gud.

Well here goes. I gently wedge my fingers around the black face plate on the left.. Tight but moving.. ok go to the bottom. Better but it is very narrow and would break if I hank on it.. ok go to bottom right.. And lo and behold the face plate/stack popped a tad out... 0k ok ... so I gently work my way around the top and then back down the left...

Yippie its out.. !!!!! Cool Took the right side Cig lighter cable off, and it slid farther out......

Ok I see the ant connection.. I start to gently work it back out..
I pull the ant and the radio is very much quieter... Bummer.... (See above description) Oh well lets experiment due to what you said....

The ant connection could have been "cleaner".. By that I mean there was some flaking or some sort of foam that was old and coming off... Hmm
Here is where I dont have all my notes....
I think I reseated the ant. In doing that the signal obviously came back into the radio. But in doing that I had to gently twist the connector to seat it.

WAIT twisting the connector..... The signal improved.. ?!?!?!?!?
Wow ok so I took the connector out and tapped it against the dash and some flaking came out. That might be either here nor there but I did it just the same...

I put the ant connector back and twisted for best sig and it was fine.
I then pushed the stack back in and the ant/connector is a right angle and when I pushed the stack back the angle got more accute and pushed the ant in toward the back of the radio... There just is too much stuff in the back of the dash... Anyway I moved the ant/connector orientation and gently pushed it back to about 1/2 inch before the stack would be seated and the signal stayed the same.

I went to work this morning with it not fully seated and listened to 610 and 810 and was happy. Granted I only live 4 blocks from work but I still got listen to it.

So my next steps I think is/are to:
1 find the best orientation for the ant/connector
2 Put a block between the radio and the connector so it does not get bent toward the radio
3 fix the connector

Anyway the inline noise filter is probably not going to work.. I dont know if that is good or bad... The connector really needs fixing I think because if I put it all back and it works now I might become a problem with the vibrations of driving....

RobbieD what are your thoughts that might add to my detective work???

Will keep you posted.

Jacq..

 

[RobbieD]

Hello Jacq, and thank you for your post. My first thought, actually, is "good writing, dude!"; I really enjoyed reading your entertaining account of your trails and tribulations.

As far as your next step, I would try your option number 3. Sounds like you just have a bad antenna plug connection; over time the plug and socket it goes into oxidizes and the connection deteriorates. Get a soft-bristled wire brush and brush the plug clean of oxidation. Also gently pry out on any tabs or contacts on the larger grounding part, to ensure a better contact.

The socket is tougher; a gun-cleaning bore brush, say .30 cal. or .38/9mm, will clean up the larger ground part of the radio's socket. The smaller signal part of the socket is tougher to find an appropriate cleaning tool, but a pipe cleaner will work (the old-fashion fuzz on a wire kind). Don't go too deep, and don't have the radio on when you do this; better still to unplug the power wiring harness.

I gotta hand it to you; you're doing a great job at researching, and working on, this thing. I think if you just clean up the antenna plug and the radio's antenna socket, your AM will likely be back to normal. Still wouldn't hurt to check those antenna base screws.

Good luck, and do let us know how it turns out.

 

[jacq]

RobbieD thank you for the compliment!!

I knew it was going to be long but I wanted to give the thread the full scope of my discoveries.... thank you for reading the whole thing

Anyway... I will definitely try the cleaning methods you suggested.. I think I have some of those in the house but if not my buddies do...

I went to lunch to day drove it abt 2 miles or so and it was doing great..
On the way back I thought what the heck push it back in as it was having the tendency to slide out and hit my shifter...

I did geeeeeennnntttllly and the am stayed!!!!!!!!!

Yipppie.. I know for now... that is at best a work around but until I can get to it again this weekend at least it will be protected...

RobbieD... Do you think I am going to need to redo the connector?? I know you have no way of knowing without pix... Maybe I will take some.

I am wondering if the center conductor is getting bent to much and has failed...

I really should, now that I have hopefully narrowed it down, inspect the construction of the connector...

Ill probably dork with it some more this weekend....
Jacq..

 

[RobbieD]

Just clean it up. If the center conductor failed, or had an open circuit, you'd have no AM at all.

 

[Bill]

The first thing you need to do is figure out if the noise is coming through the antenna or propagated through the wiring and into the radio. Try disconnecting the antenna. If the noise disappears then you have to figure out what is generating the noise. It is still possible that the noise is being propagated through the wiring but the radio is filtering it out at the power leads.

You can pull the fuses to find out what circuit is causing the problem. The fuel pump fuse and the air bag system have been known to make a lot of noise in Ford vehicles.

In my 1995 Ranger the airbag module makes the hashing noise, which is being radiated via common mode propagation through the wiring harness.

Edit--
***Oooops, I missed the resolution part of this thread.