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Building a simple Alternator whine / ignition filter

Thanks soulcode I will be trying this ASAP as my magnum 257hp has this issue. Not on tx as far as I know but rx is a killer. I hope this works. I know a lot of noise gets picked up by the antenna and I have all my equipment properly grounded, but I can't get passed the alternator whine!!! If this works like shown then it's a god sent!! What a mess trying to hear people over the engine whine especially when I am at higher rpm's. Thanks for the link and god bless.
 
hi everyone. i'm from the philippines, I came across this thread while desperately looking for a solution to cure the alternator whine of my portable lcd tv (chinese made). i use a fm transmitter to hook-up the sound to my car's stock audio system. the lcd tv is producing the annoying alternator whine (thru the cigar lighter socket). i even tried connecting the tv direct to battery but the whine is still there.

moleculo's post solved the problem, only, since i'm a cheapskate and a quick link costs more than 10USD here, so I just used tie wire rolled like a rope as inductor core, and a 4700 uF 25V capacitor (can't find a 35V) and it worked like a charm. that's why I signed up just to say THANKS! :)

here are the materials i used:

5 meters of tie wire .30$
4700 uF 25V cap .60$
6m gauge 14 wire 3$
project box .30$
electrical tape
super glue

total: less than 5$ :D[
This was posted by Beetle in another thread and I thought others would find it useful, so I'm cross posting it here. This is courtesy of Jim KB1MVX, and the original may be found here: New Page 1

I recently installed a new transceiver in my truck. On the first day of using the new radio I got reports that I was transmitting very noticeable alternator whine. I could also hear it on receive and when the radio was quiet. I checked the diodes in the alternator, verified I had good grounds, and I even ran the truck with the alternator removed to be sure that the whine was indeed from the alternator.

The alternator produces AC, which is rectified into DC. The problem is the rectification is not perfect. The DC output will have a small AC signal riding on it. That AC signal will have 9 cycles for each revolution of the alternator. Suppose your engine is idling at 600 RPM and the drive pulley ratio to your alternator is 1:3. At that engine speed your alternator is turning 1800 RPM, which is 30 rotations per second. Each rotation gives you 9 cycles of AC. Do the math and you get a 270 Hz sinusoid (not a perfect sinusoid but close enough). Cruise down the road at 2000 RPM and you get a 900 Hz sinusoid riding on your DC power supply.

I tried an off the shelf filter from Advance Auto. It did very little so I decided to build a filter. The first filter I built worked VERY well. The problem is that not everyone has the tools required to build that filter so I decided to figure out a filter design that could be built in less than an hour by anyone with basic tools, have a cost under $20, and handle a current of at least 20 Amps.

Parts List:
1/2" Quick Link from Lowe's $2.98
6x3x2" project box from Radio Shack $3.79
20' roll 12 gauge red hook up wire from Radio Shack $4.99
4700 uF 35V capacitor from Radio Shack $5.29
18" of black 16 gauge wire
electrical tape
GOOP or similar glue
3 zip ties
Total: $17.05

Directions below
Link.jpg







1/2" Quick Link will be used as the inductor core. A fellow
ham, Dave KC1LT, suggested using a shackle. I went to get
a shackle and came across this quick link. I went with the
quick link to make more efficient use of project box space.

1st_Rapp.jpg

Beginning the winding
Wrap the hook up wire around the closed side of the quick link starting
from the left as shown. Leave about 9" of wire free on the left end. Try
to keep the winds as close together and tight as possible. On the last layer
space the winds so that you have 9" of wire left on the right end. Use all 20' of wire.
Fini_Rapp.jpg

Above is the finished wrap

Red_Cap_Solder.jpg

Wrap the coils in electrical tape and close the quick link. About 1.5" from the right
end of the inductor strip 1/4" of insulation off the red wire and solder in the + lead
of the capacitor. Make sure you observe the capacitor polarity. In the picture you
can see the negative arrow on the capacitor pointing down. Solder the 18" piece of
black wire to the negative lead of the capacitor. (Above)
In%20Case.jpg

Cover the solder connections and capacitor leads with electrical tape.
Drill a 3/16" hole in both ends of the project box for the red wires. Drill
an 1/8" hole in one end of the project box for the black wire. Run the
wires through the holes. Put a zip tie on each of the three wires to limit
how far the wires can be pulled out of the box. Make sure to leave a little
slack in the wires inside the box. Using GOOP or some other thick strong
adhesive, glue the capacitor and inductor into the project box. Leave the
cover off until the glue dries.
Box_Lid.jpg

+12V Side with the capacitorto radio
Black Ground +12V to battery


Measured Filter Response:
Chart.jpg

I made this measurement using a low frequency signal generator and an oscilloscope. At 25 Hz the filter has better than 30 dB of attenuation. In other words for frequencies above 25 Hz the noise power has been knocked down by more than a factor of 1000.
I am new to practical electronics. By answering basic questions and making suggestions several folks contributed to this. In particular Dave KC1LT was very helpful. I hope this information is useful. If you use this design to build a filter or if the information presented was useful please send an email to kb1mvx@comcast.net and let me know it was worth the effort to put this together.

73
Jim
KB1MVX
I realize this is an old thread, but I would think a single chain link of similar size would work the same, and not as costly as a shackle. Might take longer to wind without the opening to wind thru.
 
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I realize this is an old thread, but I would think a single chain link of similar size would work the same, and not as costly as a shackle. Might take longer to wind without the opening to wind thru.

Yes, that will work fine too. I've done this simple project with a few different things that I had laying around the garage.
 
I would like to build this for my vehicle but cannot open the images to visually see the steps. Any suggestions as to what possible settings on my computer may be keeping me from seeing images. Thanks JBS
 
At the past i buy the 857d and a new yaesu atas 120.I install them to my car ford focus (petrol) .Τhe more I pressed the throttle the noise grows. I only try good ground to the antenna mount and to the radio , nothing of this helps.I try to find where the noise is coming , i take my kenwood f7 mode ssb and i take it close to my engine , once I approach the gasoline injectors there the noise is coming from injectors.Then i try also other things . I removed the antenna cable form the back of my radio ,no noise at all .I removed the atas form the antenna base mount ,still have the noise and i try also to give power from another battery from my other car (toyota) and having the antenna mount to ford ,still having the noise.Τhat made me lose my patience, and so I sold it.From your experience if i done this the noise had go away?
 
I try to see if my alternator have one and replace it ,but i think not have.Sometime when i have a qso at 40 metres band another ham told me that he try and work the kenwood PG-3B ,but as i see now is only 20amp so i don't think for 857d or 891 for 100 watts mobile is suitable.Kenwood have one for 25amp or 30 i think but is discontinued.That products from US have have expensive shipping cost and are for US cars not European models
I remember now the noise when i switch on my engine ,the noise coming from gasoline injectors and was specific tik-tik-tik and when i press the throttle the noise is growing and the tik-tik it was dense in time.Once i found at the web one other amateur with the same car and i send him email how and if manage to do something for this ,never take answear.Maybe i give atry once more to install hf to my car but i have to be sure, i lost money when i sell the 857d
if you watch the video my noise is similar like the noise from the injectors
 
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