Wait for what? A transponder is probably the least expensive piece of avionics that you can put in a stack.
"Wait" came from Clark's comment that the 330ES isn't available yet. We're talking a week and a half to put this in.
You can probably buy an old King KT-76a for cheap, but you still have to have the rack and connections, and you're still stuck with an old fashioned transmitter that will wear out sooner and takes more energy.
The current Cessna/ARC in the aircraft is original. No signs in the logs that it has ever been serviced. 36 years. How reliable does "reliable" need to be? "Wear out sooner?" Perhaps.
As far as "more energy" goes... Haven't really seen the ancient one causing any load issues in our stack. Lowering energy utilization doesn't really matter much. We've heard stories of older aircraft with severe limitations on the power draw but we're in good shape there.
For a few more dollars you can get a used GTX327, or if you have the capability of displaying traffic, then a 330.
Nothing to display traffic on yet. Moot point right now. Worth noting for future upgrades.
If you want to make an investment, get a 330 ES. If the rest of your avionics is older King and you have no need for GPS, traffic, Nexrad, and MFD's, the used 327 is still a better buy than a King KT76 with the manual switches.
Investments in tech are usually a loser's game. The tech will change before the other boxes go in. And usually get cheaper. This assumes competition which there isn't much of in avionics right now, against Garmin...
So... Basically it looks like the options are:
Low-end: Swap the Cessna/ARC for a serviceable one and have no changes to rack, blind encoder, antenna, anything. ~$800
Medium: Swap out the tray and possibly the encoder (are their outputs standardized?), and put in something else. If buttons/dials are a worry, go KT-76C to match the rest of the stack and cross fingers that the display doesn't act up. The Garmin GTX-327 fits nicely here also. ~$1600 plus tray.
Medium-high: Mode-S without any traffic or other data. Makes zero sense. Not even going to bother looking up which transponders will do this. No requirement to do it at our altitudes and buys us nothing. Makes airliner TCAS happier, I suppose. Helps out Big Brother with serialized transmissions if anyone cares.
High: Garmin GTX-330. ~$3300. Does Mode-S and TIS which will probably be phased out for ADS-B In/Out. No display currently on board for it.
Super-high: Garmin 330 ES. ~$5500. Supposedly future-proof. Cream o' the crop and all that jazz.
None of the above include labor, or course. Leaving the encoder alone means no static system IFR recent req'd.
That's a pretty darn big price swing to maintain the only requirement for just under 9 more years as basic Mode C.
Other thoughts:
- TIS has coverage here only around DEN and COS (granted those are the places you want it). Outside of the coverage rings around those, TIS is a barren wasteland here. Mission-wise, the airplane has been East of the Mississippi less than five times in six years. We're all go southwest (AZ, NM, UT, NV etc.) or way north by northeast (Dakotas).
- Below 18,000' UAS on 900 MHz is going to be required to utilize ADS-B properly anyway and Rocky Mtn Region hasn't even completed ground station roll-out. Zero coverage here right now. No published estimate on availability.
It's pretty tempting in light of the lack of coverage and uselessness of the data without a compatible display to just go low-end and wait to see what the market offers prior to 2020. If anything.
Perhaps someone will offer a dual mode UAS 900 MHz ADS-B In/Out and transponder combo in a single package, which makes the most sense eventually -- now that the ADS-B designers have rammed their heads up against the blatantly obvious bandwidth wall.
Did I miss something?
