Filters

[Montana Bauman]

Hey Guys what Filter would you recommend to slap on a handy talkie to filter out noise from a vehicle. I have the tendency to get noise from the alternator do to the high pitch wine on 2 Meters and its with in the Car. Running Yaesu VX8-DR with 5 Ft coax cable on a diamond SRH 940.

Thanks,

Montana

 

[Robb]

Replace the capacitor on the alternator or add another?

 

[Montana Bauman]

ill have to try it. just having the car on make so much noise. i cant squelch it all its so much. thanks again robb for the help.

 

[Captain Kilowatt]

I am assuming that you have the HT plugged into the vehicle to power it when you hear the noise. Yaesu makes a filtered DC power cord for that I believe. If you simply run on the internal battery pack do you still get the noise? I have seen some car charging cords generate a horrendous noise. I once had a DC cord that powered some long forgotten device and it caused all sorts of noise across the entire VHF spectrum rendering my 2m mobile radio almost useless. Needless to say I ditched that piece of garbage and found another one that did not use a switching type voltage converter/regulator in it.

 

[Montana Bauman]

actually im running it straight from the handhelds battery pack. just using it if i was mobile on foot. but when the car is off i can get great reception, like 30 miles but car on goes to 0.

 

[Captain Kilowatt]

actually im running it straight from the handhelds battery pack. just using it if i was mobile on foot. but when the car is off i can get great reception, like 30 miles but car on goes to 0.

I am about 99.99% sure it is NOT the alternator then. It could be fuel pump or ECM. Turn the key on but do not start it. If the noise is present for a second or tow then goes away it's the fuel pump. If the noise is there and stays with out the motor running but the switch in the RUN position it is the ECM module most likely. Alternator noise is almost always conducted noise thru the wiring and not radiated to be picked up by the antenna.

 

[Montana Bauman]

ok my bad on the confusion. i guess i got what i learned mixed up. ok ill conduct those test after work and have a report.

 

[Road Squawker]

does the noise change when the vehicle changes speed?

 

[Montana Bauman]

Good Morning Gents, Ok from turning the key to the fist position, I get static right away and does not subside. Turn key to 2nd position then I still get continuous static.

does the noise change when the vehicle changes speed?

To answer that it depends on the frequencies I am on. It does subside a bit on somethings but other than that perty consistent.

 

[Captain Kilowatt]

Good Morning Gents, Ok from turning the key to the fist position, I get static right away and does not subside.

This proves it is not the alternator since the alternator is not turning at this point. It also indicates the problem is not the fuel pump as the pump should run and pressurize the system in a couple seconds and then shut off until the vehicle is started. At least that is what happens in any vehicle I have had.

Turn key to 2nd position then I still get continuous static.
To answer that it depends on the frequencies I am on. It does subside a bit on somethings but other than that perty consistent.

This sounds like it it is the ECM computer in the vehicle and the problem has to be cured at the source. No filtering will cure it as any filter will simply reject the wanted signal on the same frequency. You have a stubborn problem. The case of the ECM may not be grounded very good so see is you can back off the mounting screws and retighten them to make a better ground connection. You may even have to wrap it in metal foil and ground that to solve the issue but that would be a last resort.

 

[Montana Bauman]

ok cool. that makes much more since. ill try the tin foil hat method with re-grounding to see if that works.

 

[Captain Kilowatt]

ok cool. that makes much more since. ill try the tin foil hat method with re-grounding to see if that works.

Do you have any accessory power cords plugged into a lighter socket or anything? I mentioned above that some of them are horrendous for spewing noise.

 

[Montana Bauman]

Just a charger for my phone, my car is petty plain Jane. I Like to keep things simple.

 

[Captain Kilowatt]

Just a charger for my phone, my car is petty plain Jane. I Like to keep things simple.

Is lighter socket switched with the key or on all the time? Unplug the charger and see if the noise goes away. I'll bet it does. I had one that was horrendous for noise.

 

[Montana Bauman]

I gave the socket and charge thing a try. and it did nothing. so still the ecm. ill have to work on it Saturday. Ill get back with ya after i tinker with it.