Alternator whine, Ham radio!

[Gary - K7GLD]

My truck has always displayed an alternator whine of about S-5 on several different radios used casually for mobile operation. But I have now permanently installed a new Icom 706 MKIIG and Hamstick monoband antennas - primarily 40/20 meters. I really need to reduce or eliminate the level of whine I am getting from the alternator - it goes away if I disconnect the antenna, so appears to be radiated intereference rather than conducted thru the power leads. Power leads are large in size, and go directly to the battery, the rig is well grounded at the radio and antenna mounts in the bed. The whine is directly related to engine speed regardless of whether the truck is in motion or not - and noise goes away completely when engine is turned off. Everyone in this group should already know the engine is purely MECHANICAL, no 'puters other than ABS - and fuel delivery is all mechanical. I'm certain my problem is RADIATED noise, and need specific advice on what bypass capacitors or filters work best, where they can be bought, and as much Dodge-specific installation info as possible on what NOT to do that might cause charging system damage.



Any help?

 

[R.E. Miller]

Sorry I can't be of help here, but thought I'd ask, how's your power shot system running. After your post about you installing it, you got me "thinking" again. Hope everything is running good!

Russell

 

[Gary - K7GLD]

HI Russel - the PS 2000 systems seems to work just great - only one RV trip so far, and somewhat limited - but leaving on a longer one thru the Sierras Thursday morning, be gone over a week. Seems to have picked up substantial pulling power - but NOW I need a better Torque converter to get the power to the road!



I posted "review" over in the towin/hauling forum. The $399 for the Power Shot system is money WELL spent!



NOW, back to my radio problem...

 

[NOMOFO]

Gary,

check out www.newmarpower.com for noise filters and "noisetape" used as shielding for power leads etc. They have helped solve numerous similar problems in marine applications that I have been involved with. Not always though.

If that doesn't help try going to www.sailmail.com and see if you can get through to Stan Honey. He is a tech wizard. Tell him Bob Pearce from Santa Cruz sent you and says Hi and/or sorry if he shouldn't have done this. Good Luck.

 

[ETOBICOKE]

Radio Noise

Gary have you tried adding ground straps to your antenna mount. What may be happening is that the coax shield is picking up the noise.

I have found that my truck required gounding straps on the doors and box to eliminate noise proplems. This also solved a SWR problem that I was having, it had been impossible to get the antenna trimmed properly due to the bad ground.



Hope this helps,

Neil



ps. try http://www.bigradios.com look in the forum section

 

[Gary - K7GLD]

YUP - healthy ground straps about 6 inches long directly from antenna mount to the bed rail, all clean and solid ground...



BELIEVE me fellas, this IS alternator generated, *radiated RF* noise, and the ONLY thing that's gonna stop it is some form of RF bypassing or filtering at the alternator itself! I just need specific recommendations on exactly WHAT devices are likely to work best without danger to my alternator...



Meanwhile. I'll check your pointers - thanks!

 

[ETOBICOKE]

Ferrite Toroid

Gary seems like you are sure that the noise radiated RF, why not try adding toroids to all the cables going to your transceiver and possibly at the alternator as well. Have heard about a similar RF problem, it turned out that it was getting into the radio via the remote speaker cable, trimming it shorter fixed the problem.

Another possibility is that you have a diode going south in your alternator. If you have access to an oscilloscope you could quickly tell if the alternator is making noise. Could also use a hand held frequency scanner to do this as well.

Have found that the seat belt buzzer and air horn compressor make plenty of noise on my RCI2950, it just may be possible that somethig else is causing the noise when the engine is running.





Neil

 

[Gary - K7GLD]

I appreciate the effort here guys, I really do - but this is my SECOND alternator since the truck was new, BOTH do the SAME thing, and I sorta doubt BOTH could be bad the same way - and as I pointed out in the lead post:



" it goes away if I disconnect the antenna, so appears to be radiated intereference rather than conducted thru the power leads. "



THAT sorta eliminates power leads as a source bringing interference back to the rig I would think...



" The whine is directly related to engine speed regardless of whether the truck is in motion or not - and noise goes away completely when engine is turned off"



And THAT would pretty well eliminate things like seat buzzers and speaker leads - or air horn compressors...



Again, believe me, the alternator IS in good operating condition, I'm NOT trying to FIND where the problem is originating, I already KNOW! The noise IS generated by the alternator and radiated as RF frequency interference thru the AIR to the antenna and into the radio - NOT being fed via power leads - everything IS well grounded... There is NO "mystery" as to where and HOW the noise is originating - I simply need to know WHAT components to use in the generator circuit that WILL eliminate the RF whine (remember the old spark-gap transmitters? SAME THING!) and NOT damage my generator - and WHERE these specific components can be obtained!



I'm TRYING to avoid butchering up my wiring with a lot of trial-and-error guesswork blindly inserting various random values of bypass capacitors and home-made inline toroid filters hap-hazzardly in my generator circuits - SOME of those CAN cause damage to the charging circuit and alternator! These trucks are used in various emergency service, commercial and military service applications where two-way radio is common - there's GOT to be an accepted and known cure for alternator whine!



I see references to various values of "Coaxial capacitors" and "brute force" RF filters that run in series with the primary generator output in similar mobile radio interference threads - I know there ARE various devices out there designed for this use, but WHERE, and which ones work best in Dodges?



SEE, I've already IDENTIFIED the problem (I think... ) - No need to "reinvent the wheel" or start trying to "find" the source of the problem, I ALREADY KNOW THE SOURCE! Now, I just need help in ELIMINATING it!

 

[Paychk]

Hey Folks



I did a little digging around, check out this post on a hummer site, might be of help.



http://www.humvee.net/hid/acc/cbnoise.html:)

 

[Gary - K7GLD]

Alan, (whew!) THANK YOU!



At LAST, a source that deals EXACTLY with my problem, AND supplies a solution and source for required device(s)!



I owe ya one!

 

[drives mopars]

Gary did u fit it?

i also have a 706 in my 93 no problems



whats ya do to fix it ?



bill

 

[Gary - K7GLD]

WELL. it's like THIS...



Having been given some good leads on components and where to obtain them, and since I had already pretty well figured the problem was RADIATED RF from the alternator, I decided to do the cheap and easy stuff first, and go to the heavy-duty and $$$ stuff afterwards...



SOOooo, I peeled the outer braid off some old RG8U coax ,and improved the battery-to-body ground, and then used some more braid to run from hood hinge mounting bolts to the fender bolts near the rear of the hood. THEN, I decided to try some "poor man's shielding" on the cable bundle running from the alternator back to and along the firewall by wrapping it with aluminum foil...



JEEZE, my alternator noise is ABSOLUTELY GONE!



Ambient noise on 40 or 20 meters is absolutely the SAME with the engine on or off, and at any engine RPM! If I listen REAL close. I can just detect slight spark-plug like noise impulses, but not enough to even use the ordinary noise blanker, let alone the DSP...



My first contact after the "noise abatement" was PA2PKZ in the Netherlands on 20 meters - not too shabby from my truck sitting out in my carport!



I'm a happy ham... And it was dirt cheap too!

 

[drives mopars]

glad its ok

i may call u on 14 or 7 somewhere



yes my battery to radiator mount wire is the short 6 ''



one that is well grounded maybe thats is why my 706



works grt

also do you want or tried a dk3 10-80 6 meter and 2 meter

screwdriver ant from orig inventor don johnson



i have his # bill

 

[Gary - K7GLD]

YUP - I have one of Don Johnsons screwdriver antennas - he lives just down the road from me, and attends our monthly local Ham breakfasts. His mobile antenna is the best thing going, just big and ugly! The Hamsticks are lots less visible, and work PRETTY good...