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GPS antenna question ?

Larry DeCamp

Well Known Member
I was advised by Stein Friday that the 2020 compliant GPS receiver requires a separate antenna from the GA26C they sold me that only works for the G3X460 screen. There is no glare shield real estate in an RV4 to place them. Some folks put them successfully FWF under fiberglass cowl. The plugs on these antennas are large relative to wires, so passthroughs to rearward areas near the roll bar could get ugly.
My question for the more experienced than me is:
1- A area in the fuse avionics cover could have a window in it to mount antennas with a sky view, cool temps, simple routing. What is best to make it from?
A-Fiberglass is proven workable, but may not be optimum.
B- Can the fiberglass be painted with the aluminum "boot cowl" that it is built into ?
C- Plexiglass could be mounted as a window. More difficult to mount, could craze.

Does anyone know how much performance is lost relative to air, for plexiglass, fiberglass and painted fiberglass ?
 
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Larry,

I have a Stratus ESG in both my Cardinal RG and my RV-3. The Cardinal has the GPS ant. on top of the wing, the RV-3 has the GPS ant. underneath the cowling. The performance (lock time, ect) is identical as far as I can tell.
 
Larry,
I have installed several types of GPS antennas under the cowlings and have had no problems, even when placed close together. If you leave one end off the connector then you only need a 1/4" hole to route the cable. I believe most Garmin installations require a minimum 6' cable length. You can fabricate a nice bracket and attach to the engine mount.

https://i.postimg.cc/G2mCzzPK/20200111-161739.jpg

[20200111-161750.jpg](https://postimg.cc/hXCgB3RS)
 
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Appreciate the replies guys !

Unfortunately, aft turtle deck not an option for me cause the 4 is a fastback. It sounds like fiberglass is no problem, nor is FWF. I dont follow the small cord passthrough concept since both Garmin boxes have round antenna connecter to mate with the antenna:confused:
 
Larry,
Cut the connector off one end, feed the cable and attach a new connector. Spruce sell BNC and TNC connectors, about $5 apeice.
 
JPM 757 question ?

I think I see in your pics, a GA36 and GA35. Stein suggested a 35 for my 20A box ( WAAS for 2020 transponder compliance). Why do you have both ?
 
The large black plastic cover around the BNC connector on the GA26C antenna is easily removed. Slide the cover up along the cable then, using sharp snips, carefully split the cover lengthwise.
 
I think I see in your pics, a GA36 and GA35. Stein suggested a 35 for my 20A box ( WAAS for 2020 transponder compliance). Why do you have both ?

Larry,
That particular installation has 2 antennas, one for the GNX375, and the other is for the G3X. 2 seperate GPS receivers.
 
Another 757 question

So what do you use for the G3X screen?Stein sent me the 26C for the 460 screen and said I need the 35 for the 20a.
 
DO NOT mount two GPS antenna's side by side as shown in the picture.

You can....but the number of people who report problems later is significant.

There might be a good reason why the various manufacturers specify not to as well. :rolleyes:
 
DO NOT mount two GPS antenna's side by side as shown in the picture.

You can....but the number of people who report problems later is significant.

There might be a good reason why the various manufacturers specify not to as well. :rolleyes:

No problems with such an installation here, nor on the other aircraft I know of locally who have done the same thing.

I'd say go for it, and if it's a problem, THEN go poking holes in your skin to mount them somewhere else. If no issues, then just leave 'em there.
 
My suggestion is to simply follow the recommendation of the equipment manufacturer as closely as possible. I thing Garmin in this case has some pretty smart folks working for them and they may know a little more than the average forum contributor.
 
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