Avionics Upgrade Completed – M20J 1980

[unicom]

Hi all,

After a long upgrade process, my 1980 M20J is finally back in the air with a completely new panel.

Here’s the clean factual list of everything that is now installed in the aircraft:

---

Primary Flight Display / Backup

• Garmin G3X Touch (PFD/MFD)

• Garmin G5 backup (EADI/EHSI)

• Remote GPS antennas for both the G3X and the G5 

---

Navigation / Communication

• Garmin GTN 650Xi (NAV/COM 1 + GPS) with FlightStream 510

• Garmin GNC 255 (COM 2 + VOR/LOC/ILS)

• Garmin GMA 245R remote audio panel

• SIRS Navigator Compass

---

Autopilot

• Garmin GFC 500 with:

  • AutoTrim

  • Yaw Damper

  • Smart Glide dedicated button

---

Engine & Sensors

• Full Garmin EIS integration

• GAP-26 Angle of Attack via GAD 26

• New blue annunciator light for the electric fuel pump, now wired into the annunciator panel

---

ADS-B / Weather / Traffic

• Garmin GTX 330ES retained (ADS-B OUT)

• Garmin GDL 50R (ADS-B IN)

• ADL-150B (Iridium weather) – displayed on the G3X

---

Additional Avionics

• L3 WX-500 Stormscope (direct to GTN650Xi)

• LHS-200-C radio altimeter (audio)

• DME retained

---

Panel Work

• One-piece custom metal panel

• Removal of KI-87 ADF

• Complete rewiring

• Updated breaker table 

---

Happy to answer questions about the install or config details if useful to anyone here.

Before the avionics retrofit:

Edited November 29 by unicom

[Guillaume]

Hi Philippe,

Nice upgrade !

May I ask you which shop did the avionic install ?

Except the trim rigging issue, how did the install go ?

[Kirch56H]

Excellent job! That will be a great panel to fly behind for a long time!

[Flyler]

Wow, that makes the old girl a real modern missile.  Very well done!  I love the yokes, too.

[unicom]

4 hours ago, Guillaume said:

Hi Philippe,

Nice upgrade !

May I ask you which shop did the avionic install ?

Except the trim rigging issue, how did the install go ?

Bonjour Guillaume,

I had the avionics upgrade done by AirTeam in the Czech Republic. It is probably one of the best avionics shops in Europe today. What really impressed me was the fact that they have an engineering department, which allows them to deliver a truly refined project. We were able to think through the integration of every instrument using detailed wiring diagrams and connection schematics, and they also came up with ideas that helped me choose the best way to modernise my aircraft.

My only criticism, beyond the trim rigging issue where they clearly didn’t do a good job (although I must say they immediately covered the re-rigging costs when I arrived in Palma, and offered compensation in the form of a 12-month Garmin subscription) — is that I would have liked to spend a bit more time in the hangar when I picked up the aircraft. Unfortunately, they are victims of their own success: when I arrived, the aircraft was parked outside in heavy rain, which wasn’t ideal from a commercial point of view and could have been handled better.

That said, I’m extremely pleased with the quality of their work, the level of detail I could follow week after week, and the immediate answers they always provided to my questions. So yes, I would definitely entrust my aircraft to them again without hesitation if I needed more avionics work in the future.

[DC_Brasil]

Very nice upgrade. Very similar to what I did with my M20J. 

I didn't have the cash to put in a new GPS, though. Now I am contemplating purchasing an used GNX375 to have a modern GPS, ADSB and retire my old King KT76A transponder.

[Jackk]

 

50 minutes ago, DC_Brasil said:

Very nice upgrade. Very similar to what I did with my M20J. 

I didn't have the cash to put in a new GPS, though. Now I am contemplating purchasing an used GNX375 to have a modern GPS, ADSB and retire my old King KT76A transponder.

 

 As long as your GPS is a WAAS Garmin (430W etc) you really are not gaining much outside of cosmetics 

 

[Jackk]

11 hours ago, unicom said:

Hi all,

After a long upgrade process, my 1980 M20J is finally back in the air with a completely new panel.

Here’s the clean factual list of everything that is now installed in the aircraft:

---

Primary Flight Display / Backup

• Garmin G3X Touch (PFD/MFD)

• Garmin G5 backup (EADI/EHSI)

• Remote GPS antennas for both the G3X and the G5 

---

Navigation / Communication

• Garmin GTN 650Xi (NAV/COM 1 + GPS) with FlightStream 510

• Garmin GNC 255 (COM 2 + VOR/LOC/ILS)

• Garmin GMA 245R remote audio panel

• SIRS Navigator Compass

---

Autopilot

• Garmin GFC 500 with:

  • AutoTrim

  • Yaw Damper

  • Smart Glide dedicated button

---

Engine & Sensors

• Full Garmin EIS integration

• GAP-26 Angle of Attack via GAD 26

• New blue annunciator light for the electric fuel pump, now wired into the annunciator panel

---

ADS-B / Weather / Traffic

• Garmin GTX 330ES retained (ADS-B OUT)

• Garmin GDL 50R (ADS-B IN)

• ADL-150B (Iridium weather) – displayed on the G3X

---

Additional Avionics

• L3 WX-500 Stormscope (direct to GTN650Xi)

• LHS-200-C radio altimeter (audio)

• DME retained

---

Panel Work

• One-piece custom metal panel

• Removal of KI-87 ADF

• Complete rewiring

• Updated breaker table 

---

Happy to answer questions about the install or config details if useful to anyone here.

Before the avionics retrofit:

Well done! 

[DC_Brasil]

48 minutes ago, Jackk said:

 

 

 As long as your GPS is a WAAS Garmin (430W etc) you really are not gaining much outside of cosmetics 

 

Nope... I have the old grumpy non WAAS GNS430

[Jackk]

20 minutes ago, DC_Brasil said:

Nope... I have the old grumpy non WAAS GNS430

ahh, still a good box however 

[ArtVandelay]

 

 
 As long as your GPS is a WAAS Garmin (430W etc) you really are not gaining much outside of cosmetics 
 

New GPS will handle routes, holds, VNAV, it’s more than just cosmetics.

[Jackk]

34 minutes ago, ArtVandelay said:

New GPS will handle routes, holds, VNAV, it’s more than just cosmetics.

 I have done all that with a 430W/530W

 

 Now if they make a new navigator that also has a built in INS or something, well that would be a upgrade 

[0TreeLemur]

@unicom - nice.   A question- in the photo your glare shield looks really to be in very good condition, like NEW.  Did you have work done to it?

The only thing I would change about your set-up is to eliminate the passive "dot" CO detector and get an active detector that beeps and flashes like a Sensorcon unit.  After that your upgrade will be more complete.

[DC_Brasil]

16 hours ago, ArtVandelay said:

New GPS will handle routes, holds, VNAV, it’s more than just cosmetics.

Yes. There are many features it adds which the old non-WAAS GNS430 doesn't have: 

• Holds
• Parallel track
• Airways
• Waypoint Alt constraints 
• VNAV integration
• G3X can send Flt Plan to the GPS
• Smart Glide

Plus the added benefit of ADSB in/out for the GNX375. 

[midlifeflyer]

16 hours ago, Jackk said:

 I have done all that with a 430W/530W

 

That's amazing since the 430W/530W doesn't have the ability to select ATC routes, create custom holds, or allow the entry of altitude constraints required for enroute VNAV. Whether one finds any of those valuable enough to upgrade is a separate question.

The only one you can sorta do is ATC routes, but that's done in ForeFlight or Garmin Pilot and pushed to the GNS as a series of waypoints. I guess you can do that for custom holds too, but it looks really silly and you have to remember to scroll back up to the fix and tap D→ if you need to go around multiple times. 

[midlifeflyer]

Nice panel, @unicom  

[Jackk]

2 hours ago, DC_Brasil said:

Yes. There are many features it adds which the old non-WAAS GNS430 doesn't have: 

• Holds
• Parallel track
• Airways
• Waypoint Alt constraints 
• VNAV integration
• G3X can send Flt Plan to the GPS
• Smart Glide

Plus the added benefit of ADSB in/out for the GNX375. 

 the airways I just put it into FF and ether send, or turn bends only on and put in the waypoints, doesn’t take long.

 

 VNAV isn’t quite as smooth for a crossing restriction, but still not too bad

 

 it has smart glide, knob fully twist, direct enter enter (don’t even have to look) at the same time I (the smart part) pitch for best glide

 

 not sure of the ADSB is a benefit, I don’t and won’t run it myself, but I get some find see pluses that outweigh the safety and security minuses  

 

 

 Speaking of which, wasn’t there like a Garmin 580 or something that was kinda rare but a step up from the 530 that did airways etc?  I remember reading they deliberately made the 430/530 no able to load cleanly a airway to sell the model up…

Edited November 30 by Jackk

[ta2too]

That was the Apollo CNX 80. It was an excellent box. Garmin bought the manufacturing rights and renamed it the 480, if my memory serves me right. A few years later, Garmin discontinued it

[MikeOH]

19 minutes ago, ta2too said:

That was the Apollo CNX 80. It was an excellent box. Garmin bought the manufacturing rights and renamed it the 480, if my memory serves me right. A few years later, Garmin discontinued it

Yeah, that was a FABULOUS box.  It almost seemed like Garmin wanted to not merely eliminate competition, which makes sense, but eliminate a better product (the CNX80/GNS480), which made NO SENSE!

[Ragsf15e]

3 hours ago, 0TreeLemur said:

@unicom - nice.   A question- in the photo your glare shield looks really to be in very good condition, like NEW.  Did you have work done to it?

The only thing I would change about your set-up is to eliminate the passive "dot" CO detector and get an active detector that beeps and flashes like a Sensorcon unit.  After that your upgrade will be more complete.

I agree, I have a sensorcon too.  The previous owner put a Guardian into my current panel and apparently they can integrate with a g3x to give you accurate real time readings just like the sensorcon as well as alarms on the g3x.  It sounds awesome and my panel is almost exactly like @unicoms, so why do I say “apparently”?  My panel has used up all the rs232 inputs which is likely similar to the OP.  The Guardian is instead connected to the eis as a “low trigger” (meant for a warning light on panels without a rs232) that will cause an alarm if CO goes over 50ppm, but losing its ability to display current level.  I like the sensorcon better.

[midlifeflyer]

16 hours ago, ta2too said:

That was the Apollo CNX 80. It was an excellent box. Garmin bought the manufacturing rights and renamed it the 480, if my memory serves me right. A few years later, Garmin discontinued it

There are several people out there who still have one. It was way ahead of it's time. Current databases are available and it includes not only Victor airways, but modern T-Routes. And it even did custom holds years before Garmin put it in anything else. Even early G1000 panels didn't do those. 

One perhaps interesting observation. I'm sure it's not a representative sample, but those I know who owned and loved the CNX80/GNS480 went Avidyne when they upgraded. Said the logic was more similar. I can't vouch for that - although I flew an airplane with a 480, it wasn't long or often enough to get to an acceptable  level of proficiency with it. 

 

[ta2too]

Very true. I went Avidyne. When the GNS 530/430 were all the rage, the biggest concern was that you could not enter an airway from point A to point B. You had to enter every single waypoint. When getting a clearance change, it was a handful sometimes for single pilot IFR to enter an amended clearance. That being said, the CNX 80 had a different keystroke format vs Garmin, but those that used them loved them. It was real competitor to the GNS radios. Who knows, maybe Garmin bought them to get the CNX patented technology once they owned it, and used it in the GTN series which turned out to be a home run.

[unicom]

On 11/30/2025 at 4:18 PM, 0TreeLemur said:

@unicom - nice.   A question- in the photo your glare shield looks really to be in very good condition, like NEW.  Did you have work done to it?

The only thing I would change about your set-up is to eliminate the passive "dot" CO detector and get an active detector that beeps and flashes like a Sensorcon unit.  After that your upgrade will be more complete.

The glareshield and all the interior of the aircraft was refurbished in 2010 by Aerocomfort in Texas. Fifteen years later, the aircraft's interior is still in perfect condition.

Sensorcon is my next buy !

[laytonl]

Great looking panel!  What did aerocomfort do to spruce up your glare shield?

lee

[unicom]

On 12/3/2025 at 3:42 AM, laytonl said:

Great looking panel!  What did aerocomfort do to spruce up your glare shield?

lee

Aerocomfort upholstered the glareshield with a vinyl finish that gives it a very nice appearance and a pleasant feel. At the time, they also applied the same treatment to all the aircraft’s plastic components, which are now covered with a vinyl layer matching the interior color. This gives the airplane a refreshed, modern look.

Before avionics upgrade: