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Have GTX330ES and GDL88, and I’ve recently been getting notified that my Mode C is intermittent. The GTX is the oldest avionics piece in my panel but I’ve never had an issue and all the cockpit checks are good. Software most recent, LRU page on GTN shows all green. No errors logged. I've checked antennas, connections and having trouble getting into my avionics shop as they’re backed up. Went to another shop and went through basics and nothing obvious. Garmin said it’s rare to have the CL105 antennas go bad and the intermittent faults are usually software, terrain/antenna masking, or potentially frequency drift. Shop was going to use another GTX330ES off the shelf to switch out as a step but unit needed to be sent to Garmin due to malfunction. Anything I can or should check? Can GTX units be bench checked? Send to Garmin for repair vs change out equipment with newer model…seems more involved than just change unit as a change would likely be trade GDL/GTX for a 345 which would need wiring and install time. What’s the typical lifespan of a GTX 330ES? PAPR usually has shown SDA fail and reports similar to below.

Talked to shop this morning. Said altitude is coming from the GTN to the xpdr so whatever source the GTN is using sends it to the transponder = altitude from the G500, but if that were to stop working the G5 would still be feeding the GTN and it would pass the altitude to the XPDR. “I do get all the A/C information at the test set however the power level is about half of what is acceptable to pass the test. I am thinking that most likely you have a bad GTX330ES, however, without another unit to swap out I cannot completely confirm that.” Sounds like repair vs exchange is most economical option. GTX335 would need to tap into HSDB, remote mount GTX345 could adopt GDL88 HSDB in tail. But both of these would be more install costs plus at least double equipment cost. Any difference between an exchange vs repair from Garmin? Any other potential causes of intermittent reception likely caused by low output signal besides faulty unit? Update: Garmin’s flat rate repair $1125, exchange $1350 for the GTX330ES. Still cheaper than 335/345 + install.

I have it linked to GTN 750Xi; no flags on GTN or on LRU page. Software 8.04 in the GTX330ES, and 3.42 in the GDL88.

I corrected my above statement to state that correlation of Active traffic from the GTS 800 and ADS-B traffic from the GDL 88 occurs within the GDL88.

I wired a GDL88 to a GTN750. I had to use the configuration tool off of the garmin web site and break into the 88 with the usb cable to configure. Old Chub

Hmm.. figure D-18 page D26... (I think I wrote that from another install manual first). As for requiring a specific manifest from Cirrus, I can't say. Many of the configuration expansions for GDL88 and GTX345R were done by manually updating the config on the RS485 and RS232 ports, manifests weren't required. This might be one of the, you can do it by loading the cirrus manifest.. but you can also do it by setting the Connext format manually. No matter what you will need a Garmin tech to load the 345R manifest which is an update to the gtx.rgn

I have a GTX330ES that’s 1090ES and ADS-b out, but GDL88 that’s ADS-b in.

Is there any logic in swapping out a perfectly good GDL88/GTX330ES combo for a GTX345R connected to a GTN? Is there any functionality gained, or lost, doing this swap? On the single point of failure topic, if you were to lose the GTN, would a remote device connected to the XPNDR, still be able to display traffic, and if the optional GPS were installed, have backup GPS for emergency navigation?

I have an 1968 M20F and installing gdl88 for adsb in. Want to put an autopilot at the same time but have only fraction of what I need for Garmin or Aero cruze. Has anybody had experience installing used S-tec and reusing their STC? What are my other options? I will be looking for complete system on ebay, from salvage yards and maybe someone here recently upgraded and wants to sell old autopilot.

I think that any change was probably done with the original panel redo before I purchased the aircraft...I'm not entirely sure how this was wired or changed from previous. But the ammeter and voltage is now digital on the MVP50 with a VOLTS and AMPS field. But you're right, to test individually you have to cycle the alt field split switch individually. Dual alternator, dual voltage regulators (which are located at bottom of co-pilot panel and are pretty easily accessible). I never really thought about it before, but a separate output for each alternator on the MVP would be nice, however I only have one battery. It would also be interesting to see both total AMP load on the system as well as the total direction of current...i.e. turn on all your equipment and show 20 amps vs showing 0.00 amp as the battery is charged and load handled by alternator. Of course if your alternator fails, or your engine is off, the amp field shows total load. So there are ways to get all the information, but you have to use the switches to "dial in" the info you're looking for. I tossed around the idea of going with a remote xpndr, but had GTX330/GDL88 and it is really pretty out of the way anyways....G500TXi, G5, GTN750/650Xi, MVP-50, GTX330/GDL88, GDL69A SXM, Aera 760...and yes even with all those screens I have an iPad for flight planning. I looked into that as well as moving the dual row annunciator to top of the copilot side and decided that this was my preferred option overall. I discovered that the 252 has a flat metal vs Encore tubular structure for the top panel attachment (I think long bodies moved to tubular and so this is similar to a change at that time in general). So it meant I had less total stack height in the radio stack than the 252.

So I was flying formation and pulled the breaker for xpndr and ads-b. Subsequently I was having drop outs on next flight with Aera 760 and with my iPad and ForeFlight. I unpaired everything, restarted iPad, then went to Connext page and added back Aera and iPad. Made sure I clicked okay on GTN first then on iPad for pairing following @PT20J’s recommendation and all is well. Bottom line, for some reason if pairing is interrupted on GTN/FS510/GDL88 it seems to corrupt future pairing as well and requires “reset”. So if you have pairing issues, try resetting everything. But you have to remove everything on your avionics as well as other devices, Aera, iPad, etc first.

I am looking for a copy of the GDL88 interconnect diagrams. Does anybody have an electronic copy? Thank you Frank

I have dual G5s, GTN650/430w, GDL88, GTX327 right now. It's the way I bought the plane and seems like a good set up so far. I'm using a GDL50 for my iPad and foreflight. Which would be more efficient to use and why a Flightstream 210 or 510 with the current panel?

I have a Garmin 650 with flight stream and gdl88. I also use Garmin pilot on my iPad. Up until recently I have never had a problem getting nexrad weather. I now get in initially, but it never updates in flight, and it will eventually disappear. Any ideas, it needs a firmware update, but I haven’t seen anywhere on Garmin that would suggest I would be having a problem. I checked and I am getting excellent satellite reception and I get the proper airplane traffic.

So I finally got my 1969 M20E. I have lots of Mooney time but this was my first experience in the short body all of mine has been mid body mostly the 'K'. I'm interested to hear what others find normal for specs & temps as I mostly only have a stock 231 to compare it to and that's a different animal. So for a list of it's mods and equipment to understand the beast. 201 windshield, Lasar cowl closure mod, oil cooler relocation, horizontal stab and vertical stab mods, Aileron/flap gap seals, brake rotation, and Power Flow Exhaust. It has a McCauley 3 blade prop as well. Inside it has Dual G5s, GTN650/GNS430W, GTX327/GDL88, JPI700, STech30. I did 3 legs from Fresno to Minnesota. First two at 13K and the 3rd leg at 9K. I noticed about 145-146kts tas at 13k and about 151-2kts tas at 9k feet. 18" @2400 at 13k and 21" @2400 at 9k. I leaned about 100 ROP got 9gph/13k and 10gph/9k. Hottest cht at 13 was about 315 and at 9K about 340. Oil in cruise was about 190-200, but on climb out in SLC(103*@4200ft elv) it got almost to 240* and I really had to sacrifice climb to keep air coming in. So questions are ....Does this all seem normal for the 'E'? Any other mods tricks etc perimeters to keep it in? Can you run LOP stock? How much does the 3 blade affect cruise? It needs to be rerigged a little on the Aileron and rudders. Brakes need to be bled( has all new pads and rotors). I noticed the mechanical ASI kind of won't increase much after about 120mph, but the G5 IAS seems to be right on.

@donkaye has talked about his additions with the Aera to a Garmin glass cockpit. I've cloned his ideas and use it similarly, although I believe he uses one of the GDL's (51/52). I have GTX330ES+GDL88 and GDL69A SXM. I use the FS510 plugged into GTN750 as well as a hard wire connection to connect the Aera 760 to the pilot yoke. I get flight data from hardwire, and ADS-B / FIS-B / XM via the FS510. My Aera 760 is fully integrated to my panel and I can pick up all the information it has.

Ok, here are the targets I am talking about. When you are on the ground and taxiing on the airport you should see other taxiing aircraft. They are brown in color. If you have your taxi chart selected you will see them moving on the chart. I wanted to find out if others with GDL88’s receive the ground traffic.

You’re right, and not just. The GDL 82 was a neat little device due to ease of install - except for needing to add the waas GPS antenna for it. What is cool is that you literally daisy chain your existing transponder cable to the unit, with another cable coming out of it to the antenna. Power and ground, voila! ADSB out with out fear of a stolen Tailbeacon as people experience. I’ve installed a bunch. Avionics shops love these because they can make bank installing them at their current rates and billing practices. The GDL88, and the 84, which is a crippled 88, both provide in and out as you correctly stated. Install is a bit more involved. The 84 is a gdl 88 which has a built in SBAS / gps location receiver, but no provisions for panel mounted “in”. Just portables when paired with a flight stream 110/210. The Garmin documentation shows that you can send in your 84 to be upgraded to an 88, but last I checked with them they were not offering it. Bear in mind an 88 ceiling is 18k unless paired with a GTX330es/gtx33. An extra 4 lbs to get rid of a panel mounted transponder plus the added cabling…

This is wrong. The GDL82 was ADSB out only. The GDL88 is ADSB IN/OUT. I have the 88 and it does bring ADSB in and displays it on your GPS, in my case a GTN650. As for the OP, I am not sure what you mean by ground targets. AFAIK, you need to be receiving ADSB towers to display targets and I don't receive any towers until a couple hundred feet off the ground.

It is their premium fabric. I think fabric is more comfortable, warm in the winter and cooler in the summer. The added benefit is it's lighter than leather. I also went with the lightest carpets without backing or sound deadening. We removed old wires and vacuum lines too, so hopefully gonna gain a little useful load. We shall see what she weighs in at! With my remote transponder and GDL88 in the tail, I'm hoping to switch to an Earth X battery to save an additional 20lbs of weight.

That swap would be at the very bottom on the list of things I would consider doing. The GDL88/GTX330ES already give out ads-b out and in. By the time this combo is ready to be replaced there will be something out there newer and even more capable than the GTX345. On top of that I definitely wouldn't get the GTX345 built-in GPS model and add another GPS antenna to the airplane. The more GPS antennas up there the more chance for interference between them. That model transponder is for people who don't already have a WAAS source. Take the money that this swap would cost and put it in an airplane reserve account. You can rest assured that you'll need it for something else down the road.

I basically have the same thing GTN650, GTX33ES, and GDL88. I already had the GDL88 in my airplane so I just removed my GTX327 and added the 33ES. The panel is nice and clean now! I wanted 1090 out for possible Canada, Mexico and Bahamas flying. It wasn't worth the extra money to me to get a new GTX345R. The extras that the 345R offers didn't really make sense for me. Bluetooth, don't really care. Already have ADSB IN on my iPad via Stratus and ADSB IN with the GDL88 on the GTN650. I've heard that the ADAHRS on the 345R isn't nearly as good as the Stratus 3. There's no battery backup if your panel goes dark & that's a big one for me. Since I already have the Stratus remotely mounted with external antennas, i saw no benefits. Maybe someone else can point out other differences. People are also selling these perfectly good GTX330ES and GTX33ES for around $1AMU. So you can go through a few of these before getting up to 345R prices.

The GTX330ES has the same ADSB out capability as the GTX345 - in the above mentioned combination the GDL88 serves only for ADSB in.

I should have better explained the benefits I see as coming from the swap. 1) Remote mounting GTX345R frees up panel space. 2) Eliminating GDL88 frees up 4lbs useful load. 3) Moving GTX345R to the avionics bay counteracts weight loss of rear mounted GDL88. 3) GTX345 w/GPS gives backup GPS accessible from portable device in case GTN dies and you lose primary GPS. Are there other benefits I’m missing, or are there any drawbacks I’m ignoring?