Smoke Test Successful. Many Questions.
 

I've got several questions here, so everybody feel free to chime in on one or all:

1. While testing the 'lectrics today all went well, but I get a very faint whine in the headset when my GRT EIS is turned on. It's only there if the intercom is turned on and is so faint you'd probably be hard pressed to hear it with the plane running, but I'd still like to know what it might be.

2. Why is it that certain manufacturers call out great big wires and fuses for low amperage devices? For example, my Icom radio claims a max draw of 2.6 amps, but the install manual says to use 18AWG wire and a 10 amp fuse.

3. Does anybody know how to set up my Lowrance 2000c to communicate with my Trutrak ADI?

4. Can anybody tell me where I put the manual for my 2000c?? :confused:

2) I don't know what any one company is doing and why but there are several reasons to use a larger gauge than required. Less voltage drop is one reason (probably not a big factor with the few feet of wire you're going to run). Behind the panel, where it gets warm to begin with, a larger gauge will run cooler. This could be a factor especially if you bundle a bunch of power cables together. If I had to guess, though, 18AWG probably just fits whatever pins they're using the best :)

4) Check the "study". Ellen even threw a little bookshelf in the master "study". That's usually where I find manuals when I can't find them anywhere else.

Try this link to down load one to read until yours is found. I some times find things when I am looking for something else. So go find you manual for you lawnmower and you will have a chance in finding lowrance manual.

http://www.lowrance.com/Manuals/default.asp

I had the same question
 

1) AUDIO noise - Usually comes from grounds. It's clearly getting to the intercoms audio amp (by audio inputs or power wires to intercom or its picking up an RF signal). I would not worry about it. With the radios on and engine running you will not hear it, but for fun try different headsets. Make sure the headphone jacks are isolated from airframe ground. All radios should grounded at one good gnd point. There's a chance the EIS display is putting out some RF (radio freq) interference. The EIS case shield it's RF but the display is right there transmitting light and possibly RF. Is the EIS close to the radio or intercom?


2) ICOM puts the 18 awg and 10 amp CB/Fuse in there because..... it works. Why minimize every wire gage and fuse to the bare min. 10 amp fuse/CB's, 18 awg wire, Done deal. It also minimizes voltage drop, and it works every time.

The internal fuse is 5 amps so that would be fine for the Fuse/CB if that is all you had on that circuit. A 5 amp fuse and 20 awg would be fine. You could go with 3 amp protection for the 2.6 amp max drain, but that is an odd sized CB. Most builders don't mind optimizing each individual circuit wire gage and adding more fuse/CB circuits for individual protection. Is there anything wrong with the ICOM suggestion? No but you don't have to follow it, but its legitimate way to go.

Others have answered the other questions. I hate to answer with a question but are you using a battery for this test? If you have a charger or a power supply connected, you could be hearing noise from that (even if the battery is also connected). If it is battery only, sounds like someone answered the quesiton by saying ground loop problem. If it goes away only when the GRT EIS is off (everything else is on), you found the source.

Did I mention it's an RV4! Just kidding George, but everything is close to everything in this little plane. Your advice is good and I'll check my grounds. I've sent an email to the EIS folks to see if they've had a lot of this type of thing. Thanks.

I appreciate the suggestion. Actually my power source is my girlfriends car cig lighter. In any case the sound is only present when the EIS is on. I thought that I did a great job with all the proper shielding, grounds, etc., so I wasn't expecting this. Since we know it's the EIS, what exactly should I be looking for?