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421

General Discussion / Re: Antenna Location & GPS Input

« on: April 05, 2017, 02:40:39 pm »

Thanks, guys, for all your replies. I was just about to reply to Peter and Ian and thought I'd got it straight but now I've been thrown a tantalising morsel by Lee 

My plan would be to mount the unit behind the panel both for ease of power supply and connecting to the EFIS units. I don't know if the PAW installed GPS would be effective from that position (glareshield above, bits of radio etc either side and the panel's metal and engine to the back and front) but that's not a huge deal; I was simply trying to get away from having another GPS antenna on top of the panel if I could. They're only tiny, so it's wouldn't affect the price of fish but it's my OCD playing up again.

The aircraft I am considering is the Eurofox (lovely looking little things) and I would imagine the antennas, if mounted inside the fabric, would be halfway down the fuselage (ish). I was quite happy to accept Peter's advice about the cable length but it would be good to find out if Lee's proposal may alleviate the problem. If not, then would the area beneath or just to the rear of the seats (below the baggage area) be the sort of place where you'd mount external antennas. I was looking at the tuned monopole whip in the shop. Would you use one of those for P3I and one for ADSB or would it just be one for P3I and the normal ADSB aerial could live inside?

If you think this level of questioning is bad, can you imagine what it will be like when I actually get an aircraft and my PAW kit 

422

General Discussion / Antenna Location & GPS Input

« on: April 05, 2017, 10:59:35 am »

Hello everyone,

I'm in the absolutely rubbish position of not owning any sort of PAW system, nor even an aircraft. However, I plan to remedy that situation and have been spending far too much time looking at goodies for my potential craft and asking far too many questions of long-suffering but patient people, such as the excellent support at MGL (sorry Paul). My plan would be to install a permanent PAW system and I have read all the the documents on the main site regarding that AND antenna location, so I'm not just going for the easy 'answer my questions' without having done some homework 

My potential steed will be fabric covered (Stitts Polyfibre) and I'd really like to know if mounting one of the tuned low profile antennas in the tail would be a decent set up. Clearly it wouldn't have too much metal around it apart from the tube fuselage and I understand it would not be a good idea to actually mount the antenna to one of those (vertical) tubes. I THINK it would be acceptable for the ADSB antenna because of the incoming signal strength but it would be good to know about the P3I reception from back there. I suppose I am in the enviable stage of being able to think about 'extras' before the order is even in and may be able to plan ahead for a couple of ground plates to be mounted in the tail before it gets covered but, if possible, I'd rather keep things nice and protected inside the fabric......and fewer bits sticking out. So, has anyone done this in a fabric covered aircraft yet and can report on their findings?

The second absolutely trivial thing I was thinking about was reducing the number of GPS antennas I would (potentially) have. At the moment my plan is to run two MGL iEFIS units and both will have separate GPS antennas. If I permanent-mount the PAW then could I use a GPS output from one of those EFIS units instead of having a third antenna on top of the glareshield? I'll be using EFIS GPS position for input to the transponder for ADSB but even if I only run one GPS 'out' from each unit then the PAW can be fed the data. As I said, trivia and only a means to have two matchboxes instead of three on the glare shield.

I'll leave my meanderings there for now as I have so many thoughts about power supplies and filters for MGL EFIS that I would bore everyone to death and that's before I've even got a toy to play with.

Thank you for your thoughts and any information on these vital questions