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Actual exact height of GTN650+GTN750

Does anyone have these two installed as shown below?

I am trying to work out if I have enough room for the TKS control panel. The below is a photoshopped mockup.

Many thanks for any feedback.

The TKS control unit is actually slightly smaller than shown above

Shoreham EGKA, United Kingdom

Form the install manual, the GTN max height is 6.00" /152.4 mm and the 650 is 2.64" /67.06mm. The racks will butt up together.

If you’re short of space for the TKS you could ditch the audio panel and install the blind GMA35, or alternatively change the transponder to a remote GTX345R and gain the space there (and then get the benefit of merged traffic/ADS-B as discussed elsewhere).

Avionics geek.
Fairoaks. EGTF

Many thanks Wigglyamp. I better measure the height of the existing stuff accurately.

It’s a good point about the remote boxes but it’s another point of failure. I really prefer the separate intercom / audio panel. And a separate transponder. It means that fixing duff boxes is a slide-in job.

Most TB installs mount the TKS control box to the right of the LH yoke tube (to the left of the landing gear switch) but it is extremely cramped in there behind the panel.

Shoreham EGKA, United Kingdom

It will work because the current stuff is 10" high, and the two GTN boxes will come to 8.64".

Interestingly, a KR87 ADF tray is about 1.3" high so the TKS controller can be mounted in that. I have a pile of these old trays and there is another pile in a certain dustbin

Shoreham EGKA, United Kingdom

Peter wrote:

It means that fixing duff boxes is a slide-in job

For the GMA-35 remote audio panel, that is exactly what you do if there is an issue.
Since it is mounted on top of the GTN750 rack, you just remove the 750 and slide the GMA35 right out. In with a new.

I think the GMA-35 is one of the coolest features of the GTN 750. At lot more features than the panel mounted options, where you are tied to the nr of available push buttons.

I would reconsider that seriously.

For the GTX remote transponder, you normally wont have any space behind the instrument panel, and must fine alternative location. So that needs some more consideration. Hiding it deep in the instrument panels depth makes servicing difficult.


You lose the intercom control if you lose the GTN750 display. Same goes for a remotely mounted transponder, I guess.

The more basic point for me would be: why do it unless necessary? Every piece of complexity makes problems bigger; much more so away from base. I have more uptime on my plane than any other owner I have ever known, and I like to keep it that way.

Shoreham EGKA, United Kingdom

Peter you can rig the remote transponder to select from both the 750 & 650 so this provides some redundancy.

The other thing is I am told that if the GTN750 fails the audio automatically defaults to box 2, perhaps you need to check this with Wigglyamp as he knows far more about this than I.

A&C is correct on both items.

Avionics geek.
Fairoaks. EGTF
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