GPS recommendations for '79 M20k with original radios

[warrenn]

Hello,

I own a 1979 Mooney 231 which I bought 30 years ago and have been using the original radios: KNS80 for Nav and KY-197, KX-170 for com. I do a lot of IFR flying and  realized both that these old radios are starting to fail (my KY-197 transmitter just started having garbled transmit audio and the KNS-80 is a little intermittent) and that without GPS my approach choices are getting limited. Can someone give me some guidance for a moderate level GPS system to replace my old radios?

Frankly, I am not a fan of Garmin (for a number of reasons) or of touch displays in the cockpit. The user interface is very important - I need something which is well-designed and easy to use.  I already have a Stratus ESGi ADS-B transponder.

Any suggestions welcome. I am willing to spend a reasonable amount of money (~$50 k) for a decent system.

Thanks in advance.

Warren Nagourney

[David Lloyd]

If you learned to use a KNS80, you can learn the simple procedures for any modern GPS.  Really, the only choices for new radios today are the Garmin 650/750, Garmin 175/355/375 and the Avidyne 440/540.  All will allow you to push the direct button select a destination fly directly there.  All will also allow you to enter a complete multi-point flight plan including instrument approaches and give you information not even dreamed about 30 years ago.  My limited experience with the Garmin 750 and 375, at first I was a little overwhelmed but in a short while found the buttonology to make sense.  I am certain the Avidynes are just as easy to learn.  The big numbered Garmins and Avidynes will also do VOR/ILS and COM radios.  The other Garmins are GPS only, GPS/COM, and GPS/TXP.  All have touchscreens.  You can't use the Garmins without touching the screen.  I don't think the Stratus will display traffic on the Garmins, don't know about the Avidyne.  Plan on upgrading your audio panel also.  PS Engineering is the best available.  My experience with the Garmin 750 was a friend's airplane.  He never used the flight plan function, always used the direct button.  Although the big screen is nice, the smaller screens and an iPad will get you there.  For IFR, any of the GPS's will require a subscription for the nav data.

Last year I had a Garmin GNX375 (GPS, Transponder, ADSB in/out), PS Engineering PMA 200B audio panel/com radio/intercom installed.  Kept my old KX165 nav/com, KCS55 HSI, and Stec 60-2 autopilot.  I was a concerned about Garmin and the touchscreen but that is behind me now.  This year a couple of Garmin 275's are going to replace the attitude indicator and KCS55 HSI.  Wish all that had been done at the same time.

[PeteMc]

I get the issues with Garmin.  But the GTN 750 or 650 is a good box.  If you have the panel space and the extra $$, I'd go with the 750.  If not, go for the 650 which is basically the size of the KNS80. 

If the FD and/or HSI are starting to give you issues.  Consider the GI 275.   Or I've got used ones that were working when removed.

(1980 K and had a very similar panel.)

[warrenn]

Thanks very much for the responses. A KNS80 sized box sounds good. I also have a barely working KR-85 which is probably useless (in the US, maybe not in Canada). I might be able to make space around the hole that removing the ADF would leave. I am not sure I want two GPSs at this time, so I might put in one and keep the KNS80, which is a wonderful device (it shows how good the old coders were that a primitive Moto 6800 does all the math on the KNS80 in real time in RNAV mode).

I also have the KFC-200 autopilot which hasn't worked in 25 years and would be very costly to repair. So the FD is only an AI but the HSI is wonderful. Still works fine.  

The iPad works beautifully with Foreflight and the Stratus 2i ADSB-in. Too bad I can't use it to fly approaches...

[carusoam]

Welcome aboard Warrenn.

Sounds like you are gearing up to do a complete panel overhaul?

 

Around here...  we see many panel refreshes...  two types....

1) All Garmin

2) Anything but Garmin...

 

Going all Garmin is a way to not get dragged into the weeds of what connector goes where... how many connectors there are...  what type of connector does that box have...

Going all Dynon isn’t perfect either...   their AP hasn’t been certified for use with a Mooney yet...

 

So...

With your budget...

You may start by listing what you want... and don’t want...

1) Display system... 

2) Nav Com GPS system...

3) Autopilot system...

4) Engine monitor

5) Transponder

6) ADSB in/out

 

 

If you have wiring skills... and have a working relationship with your mechanic... this can be really helpful...

If you are interested in pre-flown avionics... this can save a few bucks here and there...

Congrats on getting to year 30... there is a small club of like minded Mooney owners around here...

The KNS80 is really cool...  the KLN90B (GPS) looks very similar....

Start looking up various nav com gps devices...  Garmin and Avidyne are popular choices... 

 

PP thoughts only, find some panels around here you like... copy them...

Best regards,

-a-

 

[Andy95W]

On 4/14/2021 at 7:58 PM, warrenn said:

Hello,

I own a 1979 Mooney 231 which I bought 30 years ago and have been using the original radios: KNS80 for Nav and KY-197, KX-170 for com. I do a lot of IFR flying and  realized both that these old radios are starting to fail (my KY-197 transmitter just started having garbled transmit audio and the KNS-80 is a little intermittent) and that without GPS my approach choices are getting limited. Can someone give me some guidance for a moderate level GPS system to replace my old radios?

Frankly, I am not a fan of Garmin (for a number of reasons) or of touch displays in the cockpit. The user interface is very important - I need something which is well-designed and easy to use.  I already have a Stratus ESGi ADS-B transponder.

Any suggestions welcome. I am willing to spend a reasonable amount of money (~$50 k) for a decent system.

Thanks in advance.

Warren Nagourney

@warrenn

Warren- since you say that your KFC-200 doesn’t work and you have a $50k budget, and you’re already ADS-B capable, I would suggest the following:

GNC-255 NAV/COM

GNC-355 GPS/COM (WAAS)

Dual G-5s

GFC-500 autopilot

JPI digital Engine monitor

That should be nicely under $50k, and you’ll be blown away by the capabilities.  Since you say you regularly fly IFR, you’ll appreciate the autopilot more than you might realize.  And if you ever want a full glass panel, adding a G3X would be minimal additional investment.

I understand not liking Garmin.  But to get the same benefit that I’ve listed above, you will either spend a lot more money or you’ll be waiting for other autopilots to (maybe) be certified.