S

sgfreeman

Member
I need some help. I am planning to use a Garmin GNC-300XL GPS/Com, a Garmin SL-30 Nav/Com, and a Garmin GTX-327 Transponder as a avionics stack in the center of my RV-7A panel. I want to wait to purchase them until later for warranty reasons, but need to get my panel and sub-panel cut, painted, ect. I have called Garmin and a couple of panel places and get different answers for cutout requirements. Garmins website is not very helpful. Can someone answer the following questions:
1. Is it best to have one large cutout or separate cutouts for each component?
2. If separate cutouts, what are their sizes and how much space inbetween?
3. If a single cutout, what size?
4. How much extra space beyond the cutout is needed for the trays to mount and how do they mount?
5. Does anyone know where you can find clear information on physical requirements for mounting multiple Garmin units- like maybe even a real drawing?

Thanks, Scott
 
Scott,
You really need to have the trays for your radio stack to make an accurate cut. This also will help in knowing what trays will penetrate the sub-panel. Many dealers will sell the trays pre-wired before the radio purchase. Additionally, the trays can be wired to any additional instruments that you have and when the time comes the radios simply slide in. There are some excellent sites depicting how to go about it.

Rocky
 
Get the Trays

Hi Scott,

I purchased all of the trays from Stark Avionics for my stack. Everything was done and the radios were ordered about a month out from flying. This allows you to get the panel completed.

I know Stark will sell you the trays and I believe Stein will to. Of course, I committed to purchase all of my radios from Stark.
 
Scott,

I agree that if you can get the trays, that would be best. But the dimensions I just cut for my components are:

GTX327 1.71 inches high by 6.30 inches wide
SL30 1.3 inches high by 6.25 inches wide

Both of these are per the Garmin install manual (send a pm if you cannot find a copy to download and I'll send you a pdf)

Note that the bottom of the 327 tray must sit flush with the front of the panel, and the sides of the 30 tray will be flush with the panel. I ended up cutting my panel 6.25 and filing slightly to widen the part for the 327. Those dimensions are sufficient to stack the two with appropriate cooling. I don't have the 300, but suspect that you could find an install manual and get the dimensions from that.

I would go with a single cutout unless you have PLENTY of panel space. It is relatively easy to stack the components. As for mounting, you are on your own. I took a couple of triangular pieces of 0.040 Al and bent some flanges to make the side mounts. I put nutplates in the flange that mounts to the panel, and screwed these onto the back of the panel. I also put a piece of flat stock connecting the two side pieces underneath the bottom radio. Basically an Al shelf that supports the bottom radio tray, which supports the one sitting on top of it. There are dimples on the mounting trays that keep the spacing between trays appropriate. Others have made mounts from angle Al stock and various other components. Here's where you get to be creative.

My cutout is, therefore, 6.25 inches wide by 3.01 inches high (in reality, I have an airgizmo mount for my 495 Garmin on top of this as well, so the cutout is somewhat larger vertically). You should not need any additional space in the panel cut on the sides beyond the dimensions quoted. However, be sure to leave sufficient space on the side of the cutout to mount the brackets that will support the radio stack. I left about 3/4 inch, which was plenty for my mounting brackets.

The SL30 install manual does have a small diagram that gives some info on specs, but it is not great.

Another warning: both the 327 and 30 are long enough that you will have to cut holes in the next panel forward (can't remember the number right now) because they will protrude through that panel (well, you might get the 327 into the space aft of that panel, but the wires will be difficult to impossible to get to).

Hope this helps.

greg
 
Vertical spacing

Another item to consider is the vertical spacing between units.

The manuals specify a unit to unit spacing to allow for easy removal and a little clearance for the moving "locking tab" that holds the units in place. Newer Garmins and King specifiy 0.050 inches.

If you have one brand of similar units, then this spacing may be allowed for with small "bumps" on the tray... as the trays are stacked, the bumps align and give the needed spacing.

As you might expect, the makers don't want you to "mix and match", so there seems to be no standard location for these bumps....:rolleyes:

Even Garmin ones are different with the older ex-Apollo radios... and the even older stuff (like my GX-65) does not have any of these bumps. My King KY-97A and Garmin GTX-320 both had bumps, but they didn't align.

You really need the trays, or very detailed information to get this dimension correct, and the dimensions are cumulative as you have more units in the stack...

From King KY-97A

2.3.2.B. When installing two or more panel mounted units in a stack, the mounting trays shall be spaced 0.050 inches (0.127 cm) apart. Current production mounting trays have 0.025 inch (0.064 cm) dimples built in to top and bottom and both sides so that the trays will automatically be spaced properly.

From Garmin 320

Figure gives a 1.71 inch overall height including 0.025 dimple top and bottom.

From Apollo GX65

Minimum 0.040 spacing for locking tab.... reccommend 1/8 to 1/4 for air circulation for cooling.

Get they trays.... especially if you "mix and match"....:)

gil A
 
Buying trays ...

Just a snipped of my experience buying a transponder.

I bought a tray for the 327 from one vendor, and found out later that I was charged 300% markup from regular price for it (I paid $100... retail price is $30). When contacting the vendor, he informed me that if I bought the transponder from him, the extra markup would be absorbed into the total price.

I decided then that I was going with another vendor, as I did not feel comfortable proceeding with this purchase. Lesson learned.

My advice: shop around when buying the tray and transponder, and find out if there are any 'hooks' built-in to the price.
 
Scott,

Used a popsicle stick for vertical spacing between my trays and it worked out very well.

As for the hole, you may wish to consider cutting the panel from top to bottom, putting in angle aluminum up both sides to hold the radios, and then fill in any blanks with a piece of aluminum. That will make future upgrades much easier.



Better yet, get an Affordable Panels panel, I think Stein might sell them now, as it locates the radio stack for you.
 
Panel

Have you looked at the panel setup form Affordable panels? www.Affordablepanels.com I used this option and am so glad I did. I just completed a major avionics change and the modular set-up made it very easy compaired with having to cut and remount everything. Fabin is great to work with and certianly worth talking to.

Regards,
Larry
N13LF
RV-7A
 
You must log in or register to reply here.