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B&C Alternator noise

Roger Peterson

Registered User
Sweeny, Texas
I have recently been experiencing a noise on transmit that is a 2 tone warble. I can get the noise to stop by pulling the breaker on my alternator. The people that have been giving me reports on the noise say it is about as loud as my speech. I have had alternator whine before, but never a 2 tone warble. My alternator is a B&C 30 amp BC433-H .
Any ideas. B&C has none. I have 2 batteries in the plane, ATP UltraBat-13.
 
for what it is worth. Five years ago I had the same problem that began on a cross country. I actually had it out on a radio shop repair in Bismarck ND. No one could figure it out. Finally took it to one of the best radio shops in New England. The "bands" needed realignment. Cost to repair was about a C note. Five years later works great. Which is not to say what your problem is, but sounds close. MY issue was xmit only. RCV was 5 square.
 
Roger Peterson said:
I have recently been experiencing a noise on transmit that is a 2 tone warble. I can get the noise to stop by pulling the breaker on my alternator. The people that have been giving me reports on the noise say it is about as loud as my speech. I have had alternator whine before, but never a 2 tone warble. My alternator is a B&C 30 amp BC433-H .
Any ideas. B&C has none. I have 2 batteries in the plane, ATP UltraBat-13.

heres a repost of quickly hunting that down, my noise with a B&C turned out to be a bad master solenoid (burnt contacts inside)... never figured that could be a cause of noise problem, but it was...

**********
This is probably overkill.... But......

My last resort way of finding/Identifying noise gremlins...

Being that the battery is the HUGE noise filter, any bad connections allow noise that normally the battery will soak up and hide, to be heard....so long before adding a noise filter, or a new Alternator, i hunt for bad connections...

So to quickly IDENTIFY the bad connection/noisy connection, or bad part...

say for example: when chasing alternator sounds

First use a temporary jumper wire from a case bolt of alternator to battery ground post, run-up test it... is sound still there? if it is gone the problem is in the ground circuit, so move end of jumper that was at battery ground to next closer connection to alt (which is the other end of the battery - strap at this 2shield step).... and repeat this till you find it...

IF the above ground directly to battery terminal did NOT make it go away.....

Then do a temp jumper wire from alt output + terminal to battery positive terminal.......run-up test it... is sound still there? if it is gone it is in the positive side of alt output circuit, so move end of jumper that was at battery positive to next closer connection to alt (which is the other end of the battery + strap at this 2shield step).....and repeat this till you find it...

If all that did not work, only then I might call it noisy alternator it self....

This method has always worked for me on different planes to find, bad master solenoid, and a corroded connection on a alt out breaker when all else failed

mike
 
I really appreciate the help, Hate to tear it apart more than once. I even thought it might be related to the increased voltage at the radio when the batteries are fully charged so was going to put a variable supply on the radio and see if it is voltage sensitive. Will post the fix, if I find it.

Thanks
 
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