HF Noise in Toyota Camry - Elmers Forum at eHam.net

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HF Noise in Toyota Camry	Reply
by N7LMJ on April 5, 2005	Mail this to a friend!
I just installed an Icom 706 and AH4 tuner into my 1998 Toyota Camry. I'm 99% sure that my fuel pump is causing the S7-s8 noise level I get on all the HF bands. I installed the radio and tuner in the trunk. The radio is on the strut tower and the tuner is under the rear window deck between the hi-fi speakers. I've grounded the tuner and the radio to the "frame" such as it is, with a #10 wire. The antenna is on a trunk lip mount and is a 102" steel whip. Has anyone solved the noise problem like that? It comes on when the key is on. Doesn't make much difference if the engine is running or not. Works great when the key is off. Thanks! 73 de Mike, N7LMJ

RE: HF Noise in Toyota Camry	Reply
by WB4YFT on April 5, 2005	Mail this to a friend!
If the noise is heard for a few seconds when you just turn on the key and then goes away, but returns when you start the engine then it is most likley the pump. This is very common with the 706. I have a Ford and had the same thing. I have a homebrew fix and will gladly share it with you, I tried it and it does work. Email me at wb4yft@comcast.net and I will give my phone # to talk about it because it's kinda involved...73, Mike

RE: HF Noise in Toyota Camry	Reply
by AA4PB on April 5, 2005	Mail this to a friend!
Fuel pump noise is pretty common. The older Ford products are noted for it. Ford is using filters on their newer products. I don't know why a 706 would be any more susseptible to it than any other HF radio. Generally it is picked up by the antenna and fed to the receiver. You can verify that by removing the antenna and seeing if you still receive the noise. The fuel pump runs for a few seconds to pressurize the lines when you first turn on the ignition (but do not start the engine). The noise therefore is present for a few seconds and then goes away until you start the engine. The fix involves putting RFI filters on the fuel pump wires so that the RFI is not radiated by the connecting wires.

RE: HF Noise in Toyota Camry	Reply
by K0BG on April 5, 2005	Mail this to a friend!
Mike, you leave a few questions that are not easy to answer. You state you have the tuner grounded with a number #10 wire. It would be best to use some 1" braid for this, and keep it as short as possible. Further, the antenna is mounted on a trunk lip mount. Not ideal, but it'll work. However, this would require the use of a short length of coax to connect the antenna to the tuner. Even a one foot piece will reduce the performance by at least 30%. The lead from the AH-4 to the antenna must be kept as short as possible as well. Read that as inches, not feet! Lastly, I suspect the noise your hear is not the fuel pump, but ignition. If you want to hear the difference, go to my web site and look under "Noise ID". I also have an article about mounting and using an auto-coupler like you have. Alan, KØBG www.k0bg.com

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