My thinking is a reluctance to rely on a transponder that may have come with the airplane itself from Wichita, and a preference to replace it at a time and place convenient for the OP. OTOH, getting a Stratus or other In-box and flying it as is for awhile is a serviceable option as well. That would definitely be the cheapest option. I’d just be ready to upgrade the transponder sooner than later. And at a potentially inconvenient time.
Definitely... But there's a whole panel full of avionics there that could be considered to be in the same category.
I have spent the better part of my Sat looking at avionics on the internet, I think I'm numb at this point. I did, to my surprise find the GTN 750 as low as $7500, and lots of GNS 530W for around the 5K range while some still wanting 10 and 12K. I did look at the Avidyne IFD 540, I like, I'm more of a button knob guy.
This is most likely not my forever airplane but one I'll keep in the 1-2 year range. I would like to be able to enjoy it and hopefully make a little when I sell it. The main motivator in this a/c is my 83yo father is 5 1/2 hours away by car and about an 1 15 by 310. Lets me drop kids at school, run up for lunch with Dad and be back in time to pick up kids. For the IFR part I want the ability to go and not have to wait until VFR conditions, plus a big seller on this plane was known ice with fairly new boots.
I can't believe some of ya'll want me to give up the ADF, cutting edge tech I tell ya, yeah it's on the gotta go list. The A/P is also what you might call cutting edge, C 400 navomatic. I don't know about functionality, I am told it works, if the wing leveler and YD work I'm good. Thanks to all I appreciate the input. One other Q: Is the GTN 750 already set up for WAAS or does it require an upgrade?
@CaptVernDemerest thanks for the extra info. You're kind of in a tough spot though, you'll generally not get your investment back on avionics. I've gotta ask, what plane is next for you?
If you've found a 750 that low, IMO the used 750 is the way to go. The market places a premium on Garmin, and the 750 is a really nice unit, with the big screen that I think you want, and it's something that's well supported and will be for a long time, and has value on the used market, and is worth the investment to install.
Now, it's really up to your budget. You could fly with the 750, hope the rest keeps working, and plan to sell in a year, and you might do OK. The original autopilot, old audio panel and radios are going to be somewhat of a liability when you sell. I could tell you to really trick it out, but if you're really committed to selling in a year or two you probably won't get all your money back unless you got a sweet deal on the plane. On the other hand, it seems that on nicer twins like the 310 there is somewhat of an expectation that it'll be better equipped than most of the singles out there, so being "cheap" may look bad when you sell.
Some things that go well with the 750:
* GTX 345 transponder will give you ADS-B In and Out, dual band (which opens up the flight levels and non-US travel) and will give you traffic and weather on the 750.
* GMA 350c audio panel gives you voice control of both itself and the 750, which is really cool. You get a button on the yoke for push-to-command and you can say things like "Tune nearest Center" or "Tune destination ATIS" or "Select Mic 1" or "Show traffic" or "Say winds" (which will vocalize the response in your headset). It makes getting around the 750 very quick and easy. This audio panel also has bluetooth if you like to listen to music while flying or you need to call for your clearance on the phone.
* FlightStream 510 will give you the ability to update your GPS databases easily via WiFi from an iPad, plus will stream traffic, weather, and attitude information to the iPad and do two-way flight plan transfer. Plan the flight in ForeFlight or Garmin Pilot at home, fire up the plane and beam your plan to the 750.
Some additional things that you may want to consider:
* Those KX radios are getting quite old. If they haven't already been overhauled, it's high time to get that done as there are likely electrolytic capacitors that are leaking by this point, and the acid from them will damage the boards in the radio, turning it into junk. If you're only going to replace one of them (with the 750), you should get the other one overhauled, with the switch contacts cleaned and electrolytic capacitors replaced at a minimum. Maybe get both of 'em done so you have a spare you can slide in.
* Some level of glass. As noted previously, you likely need to keep an old AI or turn coordinator (depending on what autopilot you have) but there's some nice capability even in the single-instrument-sized units (GI 275 and G5). Since you only have a DG right now, the electronic HSI would be a nice upgrade... And if you want to really make it nice, replacing the 6-pack with a G500 TXi would do the trick.
* It looks like you have an EDM 760 engine monitor in there? Good unit but for the plasma display. The EDM 790 gives you a nice bright LCD display and data logging and should be relatively cheap to install, re-using the existing CHT/EGT probes and harnesses.
I can easily spend six figures of your money, so if you share a budget you're looking for, maybe we can arrive at the best solution for you.
