Radio Frequency Effecting Electronics International Instruments

I'm nearly certain it's BNC, maybe Steve can confirm. Steve???

wireweinie said:

Littlewing

If you want to ground your avionics all the way back to the battery, a 10 gauge wire will be more than enough.

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thats how I've always do it...

It will mail out today. I also sent needed cables and adapters something that is also needed when you are getting a testing setup together. TEK 7 probe is "shorted" for transport. The old analogue meters hate being bounced around without being "damped". My number is in the package for coordination. When it arrives it might be wise to do the first testing on your own aircraft to get a feel for what is "normal". Particularly where the RF meter is concerned you will get some readings in a good installation so knowing what is normal on say the 12 volt bus or the ground strap in your own "good" plane will let you know what an abnormal reading is on the other one in the same general area. The "magic" of the tek meter is that the test lead is actually a coax and the probe part has the rectifier built into it and the test extension is only a half inch long, also there is a very small cap in the probe to prevent the probe from "loading" the circuit being tested and skewing the test to being meaningless. Say you measure .3 volts RF on your 12 volt bus under the panel (with a sensitive meter there will be some RF everywhere) on your plane but find 3 volts RF in the bad one at about the same point then you can safely assume either "your" transmitter is dead or the bad plane has a 12 volt/RF problem and then you have a direction to start in with ferrite beads, uncoiling some wire the RF is backing up behind or bypassing with caps, better grounding etc. If testing a ground you can work your way back to where the ground is not failing (remember not necessarily bad from an DC ohm standpoint. Were talking RF and it sees impedance which is RF resistance and can be caused by just putting some coils in a cable! You can test right across both batteries for comparison purposes and see if that is a problem. Anyway well try this stuff over the phone when you get the equipment and then you can write it up from a mechanics standpoint to post. Nothing about this should bother the FAA (unless you actually move a cable that could interfere with controls or cause a fire) and it would be expensive for an avionics shop to spend the time on this so should save some money and if successful maybe all the posts and coming at this from various angles will help someone else in the future. I think we can remove the "gremlin" status from most of this and have some fun in the process.

Thanks QSMX! I'm really blessed to have your help. Great idea on testing my airplane first for familiarization. Funny, but before I read your last post, I was just thinking that this may be of use to some poor sap like myself someday. This community should be grateful for your generosity too, and I'm sure they are.

I look forward to speaking with you soon.

Run your RF probe along a coax, and you will see high and low spots...the 'ground' of the coax 'shield' doesn't really exist at radio frequencies....realize also that it is also radiating magnetic energy,(which you won't pick up, unless you have a wire loop on the end of your probe) which is mostly cancelled after 4 inches distance or so....as it has been said, proximity is everything.

Thank you so much qsmx440. I am very grateful for your willingness to help us fix my airplane. Lending little wing the equipment neccesary to troubleshoot is an incredibly nice thing to do. He is willing to purchase the electronics but as you pointed out this gives him time to do the research required to get what he needs/wants and it speeds up my recovery.

Many thanks go out to you and others that have posted, and to "little wing" for being so kind to take on this daunting task. I am VERY appreciative.