Getting the Transponder to Seat in Its Tray

Had a devil of a time getting the transponder to seat in its tray. I finally got it in and correctly seated after playing with it, but, I truthfully cannot tell you why it worked the last time. There must be a technique the experts use.

Starting off, the rear cam/latch has to be up for it to clear the bottom edge of the opening. Then you have to rotate the cams so the forward cam clears the bottom edge of the opening. Then it was a little more difficult to rotate the cam(s) as they were rubbing most likely on the bottom of the mounting bracket.

Getting the cam to latch at this point was my problem area. Kept playing with it until the connectors began to seat as the transponder slid in a bit more (but don't know how I finally accomplished this step).

Then the cam latched and using the allen wrench the transponder was sucked in to the correct depth.

OK you avionics guru's.......STEIN Where are ya??........what is the trick??

BTW, if the radios ever have to come out, is there a tool to grip the sides of the radio to pull them out? After backing out the cam, the radio is still sort of seated. Had the comm radio in and out twice. Had to push on the back of the radio thru the slot in the mounting tray.

I think the problem is that the cam lock hangs up on the panel. It took me 2 or 3 times to get it in. I think the easiest way to get the radios out would be to push them out from behind.

Many times, it helps to utter at least one or more of several common magic incantations while sliding the avionics units into their trays. Unfortunately I cannot post the phrases here or the naughty words filter will just turn them into strings of asterisks.


But seriously, sometimes you do just have to get at the back of the unit and wiggle/push/prod/pry/whatever on both the front and the back at the same time to get them to seat. Transponders seem to be the worst offenders. Sometimes you have to gently pry them out too when removing them, and pray you don't bust something expensive while doing it.

Have the cam situated so that you can get the xpndr to slide most of the way in. Don't use the allen wrench and cam to pull the xpndr the rest of the way in, but rather give a turn or two and then gently push on the faceplate to slide it back, then a turn or two more, etc. The cam will eventually turn and drop into the groove that retains the unit in the tray, but still continue as described until it snugs up. Hope this helps. Reversing for taking the xpndr out will do you just fine also.

Had a problem also

Don't know why, but maybe when installing, the bolts can 'warp' the tray some. I had to almost hammer the units in. Neither one of the units will come out by just loosening the lock and pulling it out. I just decided to live with it. Maybe the panel base was warped some, and it did something to the trays. No idea. Did not appear to be any problem when installing the trays. They bolted in very easily.

John Bender

A Notch in the Panel

The GTX330 installation manual describes a notch that is needed in the panel to allow the cam to clear. I don't have access to the manual right now but it would be worth a look. I think it is only 1/4" wide and .030 to .060 high.

Guys...if you have to work that hard to get the radios in and out of the trays..."it ain't right"!

I'm working with Marty & Van's right now to identify exactly if/what a possible issue and resolution might be. I think I know, but I need to get it worked through first. While we are not necessarily the kit mfgr, we are the supplier of the avionics and I want everyone's installation to be as good as it can be, so please bear with us while we figure this out.

Cheers,
Stein

Transponder install problems

We had similar problems getting the transponder to slide in all the way. We removed the tray and found the transponder fit normally into the tray. Found out the problem was because the face plate of the transponder was held up by the F1202J instrument stack angles lightening hole protrusions from the punching process. We filed the protrusion smooth and the transponder fit in smoothly. Glad it is in.

John

Is it the lightning holes warping the sides of the tray, or the actual protrusion of the lightning hole material into the tray area ?

John Bender

Hi Guys,

Here's what we've found with the Txpdrs. It appears the hole as cut/made by Van's is tight to begin with (which it needs to be in order to look good finished).

In order to make the radio and txpdr mounting work well, you need to take your time and do a bit of fiddling. When mounting the racks, make sure they are not "squeezed" into the panel at all. They should fit snugly, but not tightly into the opening.

Basically here is the deal. Take your time to fit the trays into the opening first. Make sure the trays fit very nicely....if the trays fit poorly so will the units. If the trays fit nicely, then the units should as well.

Lastly, since the radio tray is not as wide as the Txpdr tray, we've found it a good idea to often times "shim" the radio tray to match the width of the Transponder tray (as to not pinch the txpdr tray together) with either some thin aluminum or "L" (Light) washers between the tray and mounting angles. Also, you should take a small file and make a notch in the bottom of the radio opening to accommodate the cam on the bottom of the txpdr. This little cutout does not need to be huge, but should allow for the cam to pass the panel without a lot of interference or need to rotate it out of the way (while holding the txpdr up towards the top of it's tray during insertion).

Overall, the only hint I can give is to spend the time to make the trays fit very well (no pinching, no oil canning, etc..) and then the radio and txpdr should fit well.

Cheers,
Stein

2johns said:

We had similar problems getting the transponder to slide in all the way. We removed the tray and found the transponder fit normally into the tray. Found out the problem was because the face plate of the transponder was held up by the F1202J instrument stack angles lightening hole protrusions from the punching process. We filed the protrusion smooth and the transponder fit in smoothly. Glad it is in.

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Can this be done with the trays still in the panel?


Thanks Stein!

Thanks Stein

Filing the notch in the panel fixed my problem. Filed a notch about 1/32 inch deep. Didn't touch the trays.

Trouble inserting the transponder

2johns said:

We had similar problems getting the transponder to slide in all the way. We removed the tray and found the transponder fit normally into the tray. Found out the problem was because the face plate of the transponder was held up by the F1202J instrument stack angles lightening hole protrusions from the punching process. We filed the protrusion smooth and the transponder fit in smoothly. Glad it is in.

Click to expand...

I filed off the stack angles where I thought the lightening holes blocked insertion of the transponder, but still could not get it in the rack. I tried bending the angles out, but that did not work either. I finally made two spacers to spread the angles out so that the transponder would clear. That worked.

Jim:

Specifically, where did you place the spacers??

jamescone said:

I I finally made two spacers to spread the angles out so that the transponder would clear. That worked.

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MartySantic said:

Jim:

Specifically, where did you place the spacers??

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Jim, pics would be real nice!

Transponder rack spacers

MartySantic said:

Jim:

Specifically, where did you place the spacers??

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I put them between the attach angles and the transponder rack at the front where the two screws on each side go. The spacers are pieces of .040 aluminum with two holes that line up with the holes in the transponder rack. I made the holes in the spacers over sized so that it was easier to get the little screws to line up with the attach angles with the spacers in place.

Thanks to Jim & John

I just finished re-doing the trays. I used a hammer and punch, and lightly bent the lightening hole protrusions back a ways. I also put shims between the tray and brackets on the upper tray. I did not grind a notch on the bottom. They both work VERY well now. The real problem was the protrusion into the area where the two units face plates needed to insert a ways, that the protrusions interfered with.

John Bender

Prolem SOLVED!

Spent the day disassembling the radio stack. When I finally removed the VHF radio and the transponder and examined them, it was obvious why, they were so hard to install or remove. There were rub marks on the side of both near the faceplate. Both were rubbing on the protrusions (caused by stamping the lightening holes) on both the left and right stack angles.

I used a punch and a hammer and carefully bent the protrusions back. Then filed them flat and primed all of my scratch marks. With the trays not yet installed I was then able to slip both the transponder and the comm radio thru the faceplate without any side rubbing. (This was with the trays removed).

Had filed a small notch immediately below the transponder for cam clearance. Reinstalled the trays and used four 0.025" shims on each side on the comm radio as it is about 0.050-0.060" narrower than the transponder.

Inserted the transponder and it slid right in. Same for the comm radio. Both sucked right in to their final position using the cam.

Stein was right, in that, one should be able to remove the radios with finger pressure if everything is aligned.

The protrusions in the stack angles were most definitely the major contributor to my original problem.

Thanks Stein, and the rest that replied to my original question. Problem solved!!

JBPILOT said:

The real problem was the protrusion into the area where the two units face plates needed to insert a ways, that the protrusions interfered with.

John Bender

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These litening holes seem to be the problem, they are too big for this application. The bend is too close to the edge of the hole. Plus my powder coat took up some room. I used a punch and a die grinder and removed a little metal and finished it off with a scotch brite wheel to smooth everything out again. I did add the notch in the panel and the transponder now goes in and out great.

Good easy fix!