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Author Topic: FT-8800R interference help  (Read 615 times)
KE5BKA
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« on: May 08, 2004, 01:20:03 AM »

New ham and I just installed the FT-8800R in my GMC Sierra pickup.  

I'm getting the dreaded accelerator hum as the rpms go up.  Shut off the engine and no hum.  

Suggestions to reduce the interference?

Thanks,
Chris
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K0BG
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« Reply #1 on: May 08, 2004, 09:41:57 AM »

Hum. What sort of hum? Is it ignition noise, alternator whine???

Alan, KØBG
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KE5BKA
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« Reply #2 on: May 08, 2004, 09:46:16 AM »

I would say alternator noise.  It's a somewhat high pitched squeel that starts low but gets higher as rpm's go up.  

It's also only on receive, if no signal to receive, everything is quiet.  When I receive someone's transmission, you can hear it.
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K0BG
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« Reply #3 on: May 08, 2004, 07:11:18 PM »

I should have known. GM products (with Toyota a close second) are the worse offenders when it comes to alternator whine. Unfortunately, this IS NOT an item you can get covered under warranty. In fact, there is a TSB about the problem, and if your vehicle is still under warranty, and you get rather nasty, you might (that is might) get them to fix it.

Alternator whine is caused by one or more leaky diodes. If the alternator puts out the requisite voltage and current, GM just doesn't care. To my knowledge, only Ford and Nippon Denso (Honda, Acura, some late-model Toyotas, Kia, and some Nissons) specifiy a level of acceptable ripple.

BTW, the cost of a brute-force filter large enough (>100 amps) to cover up the problem will most likely cost you more than a new alternator. But alas, new ones (from GM) are no better due to the aforementioned.

One last note: Some rigs are more susceptable to alternator whine than others. Sorry, but Yaesu is in the league.

Alan, KØBG
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KE5BKA
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« Reply #4 on: May 08, 2004, 10:30:10 PM »

Thanks for the help.  It is still under warranty, but may not be worth it.

I drove around today and only noticed it at lower speeds...anything above 40 was either too high for me to hear or was covered up by road noise.

I guess my next vehicle just might be a Ford!
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KD5UJX
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« Reply #5 on: May 10, 2004, 05:30:57 PM »

an easy test, take off the coax and if the noise is still there, it's comming in from the DC feed line.  If it's gone, it's RFI and you will need to look elsewhere.  

How is your 8800 wired?  Did you go DIRECT to the battery?  Are your leads as short as they can be? Have you tried ferrite beads on your DC leads?

DO NOT use the fuse box in the cab.  DO NOT use the cig lighter plug.  GO DIRECTLY TO THE BATTERY!  
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KB7EFZ
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« Reply #6 on: May 13, 2004, 01:56:18 AM »

My '95 Sierra exhibits the same problem with the FT-8100R, it's in the TX audio as well.  A new alternator when the old one failed has *audible* (stand next to the car and listen to the whistle) alternator diode noise (!) - The car parts store in town said I could return it and see if another was quieter.

An interesting and frustrating problem.  Good luck.  Our suburban has no such problem - even though the powertrain is virtually identical.  Makes no sense to me.

As far as Yaesu goes, they also make the best mobile HF rig - the FT-100.  It takes "best" due to it's IF noise blanker.  One of the hottest mobile receive setups I've ever encountered.
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NA4IT
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« Reply #7 on: May 21, 2004, 01:09:07 AM »

Might try one of the noise filter capacitors sold at these kids car stereo stores. They carry some high amperage stuff at a resonable price. Also, GM alternators are probably in the $200 range, so a capacitor is a lot cheaper.
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