ASTRO VAN RADIO STATIC ON AM BAND ONLY

[mello000]

I have a Radio Question
Can anyone help?



I listen to the Fan on the AM Band ----660
I am a METS fan---------please don't hold it against me ----fell sorry so me
This AM radio station gets static when engine starts
FM bands Fine.
I have done a number of things to stop this static

1)Changed antenna
2)Changed radio found in junkyard for$ 10.00-actually two Radios
3)4)Grounded out radio
4)grounded out tail pipe to body
5)Changed Distributor cap and Roter
6)Changed spark plug wires Denso resister iridium plugs
7)changed plug wires to Denso-resister type
Denso indicates these wires exceed factory Specs
8)Installed New Alternator--not changed for radio simply went bad

Still Static on 660 AM FAN

Could the factory type Radio for 1999 Astro Van simply have this flaw
Could Solution could be to buy better Radio
or might you recommend any other another action by me
I am willing to try anything


Sincerely
Richard

[Big_kid]

How's the insulation under the dog house? IIRC it's foil lined, this is supposed to help with the noise. Are the ignition components AC Delco? I realize Denso says they exceed OEM specs- this could simply mean that their wires are 1 mm longer than a GM wire- and technically that does exceed OEM spec.

Funny thing- when an AM station starts to fade in my Express van, stepping on the brake helps.

You might try stopping by a stereo shop for more tips & tricks. A noise filter (they'll have them) might help.

[rev_les]

How's the insulation under the dog house?

IIRC it's foil lined, this is supposed to help with the noise.

You are correct, AND the foil liner has a ground wire hooked to it, I'd verify that the ground to it is connected.
Make sure all ground points on the vehicle are clean. Do a search on "The big 3" for some tips on better grounding. When you replaced the antenna, etc, did you check and verify that there's no corrosion on the antenna wire itself?
One Important question; is the static steady in frequency, or does it rise in pitch as the engine revs higher?
A steady frequency is typical of a ground loop, where a rising pitch would be electrical interference.
Any amps, or is it a bone stock system?

[LEVE]

It could be alternator EFI riding in on the antenna.

[JaxSPL]

AM radio is notorious for picking up static. Listen to a CB radio with the squealch knob turned all the way down. Same thing (CD radio is AM radio for those that do not know). There are a lot of things that will cause a signal to detoriate:

1) weather
2) sun spots
3) buildings
4) trees
5) distance

plus the things that you've mentioned and a lot more can be added. This is just something that happens with Amplitude Modulation receivers and is one of the reasons Frequency Modulation (FM) came into existance.

Now that I got that out of the way... There are some things you can do to help with the signal. You say you've replaced the antenna. Did the replacement antenna have a higher gain than the one that was there? All antennas have a certain gain to them and "supposedly" can pick up signals better than others. The higher the gain, the better the signal, supposedly.

The antenna on the vans, and most vehicles, are actually put in the wrong locations. One the astro/Safari, the antenna is on the passenger front. The strongest signal you'll get is going to come from the driver side rear corner. This is called a ground plane, which AM relies on quite a bit. The more metal (ground) around the antenna (on the vehicle), the better the reception.

The best location for antenna placement on a vehicle is dead center top of vehicle (the roof). This will get pretty much the same signal all the way around with a little loss on the sides.

I have seen some people put an antenna on the roof, near the front and center (right over windshield where it curves to the actual roof). They have gotten great results by doing that. It looks wierd and I wouldn't recommend it unless you can seal everything up properly so it won't leak any time in the future.

Sorry about the lecture. I did not plan this post to be that way, but I do hope it helps you some way. I hear people complaining about reception all the time, especially on AM stations and tend to go overboard, like here, when talking about it.

[mello000]

Thank you
Big Kid
Rev_Les
Leve
Jax XPL--- Dennis
For taking your time to help

1) I purchased Denso electrical parts -plugs wires thinking they were better then Delco factory
I was probably wrong.
Any recommendations on best replacement Electrical parts--DELCO?
I did not mention in my Post but I tried noise filter with no change.
I went to audio shop and they sold me filter
I checked for foil around wires under doghouse and see black plastic covering wire taped
There does not appear to be any foil over wires under doghouse -I will do
Should I use household Reynolds aluminum or another type ?
Should I cover and cover all exposed wires to radio?
Any recommendations on how to attach ground wire to Foil?

2) I found 2 antennae s in Junkyard tried both same result -both very clean
One has spirals like a screw is this better then a smooth mast to pull in signals ?

I grounded out radio from neg side of battery
Not absolutely sure about static as RPM increases
I will certainly check static as I increase RPM later and POST the result
BONE STOCK SYSTEM

3) Alternator is new -3 months old
EFI I do not understand riding in on antennae
Can I correct if this is problem

4 I mentioned Antennae s in #2 any recommendations on better gain antennae for my Astro -I will replace
I would hope not to move to roof last resort
I greatly appreciate your advise and others and never consider lecture

Again I thank you for your kind replies
Sincerely
Richard

[astroturf]

The foil that's spoken of is lining the dog house cover. The ground to foil can be seen before removing the dog house and is attached to the passenger side of the dog house.
Could your radio be bad?

[Lumpy]

...any recommendations on better gain antennae for my Astro...

There is really no such thing as a "gain antenna" for the AM band.
A "unity gain" (no gain) antenna for the AM band would be about
234 feet long. Although I personally would get a camo woody with
an antenna that long on my van, it's obviously pretty impractical.

The ~28 inch whip on our vehicles is about unity
gain for the FM broadcast band. It's a severe compromise for
the AM bands. We typically don't need, nor can we engineer,
a gain antenna for the AM band. Tiny handheld AM radios,
like we had in the 60s, didn't even have an antenna to speak of,
just a coil of wire inside the case. Essentially ALL AM band radio
antennas are negative gain.

But even if there was, it's useful to first decide where the noise
is coming from. If the noise is being injected into the antenna
externally, then any antenna will continue to pick that up.

RFI problems are a pain because there are so many possible sources
of the RF interference. That's why it's a lot less hair pulling to
track down the source instead of blindly applying "fixes".

First, narrow down WHEN the RFI occurrs.
For example:

Is it when the engine is running?

If so, is it when engine runs when parked or when moving or both?
If either, does the noise fluctuate with RPMS.
If not, is it when ign key is on but engine is not yet started?
If not, does it occurr when vehicle is coasting in neutral, engine off?

That much will tend to narrow it down to an engine component, driveline
component or perhaps both.

Then, discover if the RFI enters your radio from EXTERNAL to the antenna,
INTERNAL to the antenna or from the radio power or speaker leads.

For example:

Repeat the conditions that cause the interference and bring a portable AM
radio to the van. See if the same interference is happening on that portable
radio. If it is, then the RFI is likely entering the van radio from EXTERNAL
to the antenna. ie, the antenna is picking up the interference. If that is
the case, try disconnecting the antenna to the van radio at the motorolla
plug. If the interference goes away, then it's a pretty sure bet the RFI
is entering the external antenna.

To discover if it's the antenna coax cable or radio antenna input,
disconnect the antenna from the coax AT THE ANTENNA. Do you
still have noise? If so, then ground the antenna cable tip to the
van body/chassis. If that kills the noise, then it's a good bet the
noise is entering the radio from the coax cable or one of it's
connectors. That's a pretty weak part of the chain. Spend a bit
of energy making sure the connectors are tight, clean, etc.

If none of that antenna and portable AM radio seem to point to an
external antenna ingress of interference, then experiment with
power leads and speaker leads.

For power leads, see if you can power the radio from an external
12v source other than your van. Difficult to do with some radios.
But try and bring a separate 12v battery into the cab, connect THAT
to the radio while disconnecting the vehicle battery. If that reveals
the RFI going away with the spare battery, then it's a good bet that
it's the wiring of the power supply to your radio.

Speaker leads are typically the least likely in the situation you describe.
Otherwise the noise would tend to occurr on AM, FM, CD, any audio source.
But you could troubleshoot those by disconnecting the vehicle speakers
and temporarily wiring in some other speaker, like a computer speaker
(those are cheap at Goodwill) or even headphones (be careful with the
volume).

One way or another, you've got several ways that RFI is entering your
system.
Antenna
Power
Speaker wiring

Almost always, in the situation you describe, it's entering AT THE ANTENNA.
Disconnect that and see if it's resolved. Then test/replace the coax cable,
sand any ground points to bare metal, be sure that fender (where the
antenna mounts) is bonded to the chassis and negative terminal of
the battery (run braided ground straps between panels).

It's a lot of work chasing RFI. I've got a gremlin that seems to be
coming from my drivetrain that I haven't been able to hunt down.


Craig 'Lumpy' Lemke

www.n0eq.com

[rev_les]

Nice detail Lumpy!

[astroturf]

Great Work Lumpy

Thanks, Jim

[mello000]

Thank you Lumpy
You certainly are knowledgeable.
I am away weekend but in week will print out your great instructions and check
I will post after thorough check
Sincerely
Richard

[RECox286]

IMHO and FWIW,

Not to be funny, but why listen to AM, when you have good FM, then just add Sirius for cheap/mo,
and get to listen to whatever you want? Seems like you are trying to squeeze thru a knot hole for nothing... especially if you only get noise on 1 station.

Bob

[94 Van Guy]

Not much talk on FM.

[Big_kid]

Hey now- *I* listen to AM in my work van!

I used to try DX'ing- seeing what the furthest station I could receive was. Call it research if you want- I did a term paper on the effects of the atmosphere on radio waves (2 atmospheric layers combine at night, allowing radio waves to bounce back down, or in old CB terms, "skip").

Also- the OP did say he likes to listen to the FAN- 660 AM. Born and raised in NY, I can relate.

[BusDriverStu]

If I replace the stock stereo with an after market should that fix static issues? My radio has worked a few times since I got my astro last week but I want to have an aux pl and sub anyways... Curious if it won't be worth the money if the interferance continues.