Chapter 22 – Transponder install

I’ve been thinking about my Trig TT22 Transponder install for literally years now.

Then, when Marco installed the same model to meet the 2020 ADS-B requirement it spawned even more discussion and thought.

My original plan was to mount the unit behind the panel and place the antenna out at the end of the right strake. Well, I forgot to account for the size & length of the serial adapter that lets the HXr control the Trig TT22.

Then came the ensuing interference between the fully assembled Trig TT22 transponder with serial adapter installed and the rather boxy TruTrak ADI housing. Moreover, I didn’t take into account the protrusion forward of the 90° TNC antenna connector… that takes up a fair bit of space on its own. The reality was –as originally planned– that installing the Trig adjacent to the TT ADI was going to be extremely tight, if even physically possible, without some significant configuration changes.

Another issue, even more critical than above, was after digging into the Trig TT22 manual I realized that my antenna cable run from behind the panel, along the front edge of the strake, to the transponder antenna on the outboard end of the right strake was going to be VERY close to the max length of what was acceptable according to Trig. And since my strakes are NOT installed, my estimate was best guess… at best!

Meanwhile, south of me . . . part of Marco’s menagerie of upgrades on the Long-EZ he bought was swapping out the old Nav/strobe lights with new LED lights. When he did this he was able to remove the old clunky Nav/strobe control box at the outboard end of the right strake.

Since the TT22 can be placed anywhere, he mounted the transponder control unit in the right strake where the old Nav/strobe control box had been. This configuration then allowed him to mount the antenna just forward of the control box about 15-18″ away with a very short antenna cable run.

I was down helping Marco do some of the initial wire and control unit placement and discussed the install with him after all was up and running. I was thinking seriously about doing the same Trig TT22 install but then one interesting point Marco made is that with the unit weighing in at 14 oz, he showed a notable aft-CG hit on his weight and balance. [NOTE: Marco has 2 each PC680 batteries in his nose while I only have one, thus his W&B finding is a bit more significant to me in my configuration]. Hmmm….

I then tabled the Trig transponder idea and focused on more pressing matters: my house sale in Virginia, the final move and then the subsequent house purchase in NC.

However, at this year’s Rough River I spoke with Chris Cleaver and a couple other Long-EZ owners who had put there transponder antenna in the nose area and had no obvious issues. I pondered that a bit but then left it alone again to address later.

Well, last night I had a bit of an epiphany regarding the mounting location of my Trig TT22 transponder. More specifically, I should note: the antenna. I decided that I will work the solution hard to mount the control head where I originally planned to mount it on the top shelf of my avionics mount: the Triparagon. 

Then the antenna will slip down between the front upright arms of my NG30 where there is a pocket there that really is empty space.  As a point of note, if I need to add any ballast it would go in this spot.

So this morning I grabbed the antenna and tested the fit inside this forward NG30 pocket.  Yep, it fit!  This install will result in way easier wiring of the control head, a short antenna run and fairly easy install (fingers crossed) of the antenna.

With my new Trig TT22 transponder install solution in hand, I then set about to update my wiring diagram. The updating of the Trig wiring diagram then resulted in two other diagrams needing updated. I also had not printed a few diagrams and desperately needed to print an updated table of contents page. Although my printer needs some new ink cartridges, I pressed forward (including about 45 min to get the printer on the new network) to print out these updated/missing wiring diagrams.

Bottom line: this should end the “where-to-install-the-transponder-and-antenna” saga.

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