How to Find Avionics that Best Fit your Needs and What to Look for in a Good Deal

By Bob Hart –

This article was written in 2015

In my “Avionics on a Budget” article (October 2013), I mentioned the concept of avionics that are “worth buying.” Of course, I’m referring to the purchase of used avionics and whether a person should buy a specific piece of equipment—or, perhaps more accurately, should they NOT buy it.

Until now, our discussions have been about the general “tools” you need to accomplish the kind of flying you plan for your aircraft. Part one (September 2013) covered “VFR flying” and the basic avionics needs that a strictly VFR pilot will need. Part two (November 2013) delved into the world of “light IFR” with a greater emphasis on navigation equipment and introduced the concept of redundancy. Lastly, part three (February 2014) explored the average “light-to-medium IFR” pilot for which later-model avionics are the standard.

As we now get into part four, serious IFR Flying and the special needs of the pilot who flies for business, the emphasis shifts toward newer state-of-the-art avionics equipment. Most pilots are not likely to dive into approaches to minimums with 40 year-old avionics, so this discussion is more for the pilot whose flying “budget” dictates affordable equipment. In this segment, we get specific about the opportunities and pitfalls that I’ve discovered in 16 years as an avionics consultant.

Garmin really started something when they introduced the GNS-430 a number of years back. Initially, I was resistant to the concept of integrating a comm, Nav-ILS, and IFR GPS into a single box because the idea seemed inconsistent with the concept of redundancy. After all, with the failure of one integrated unit in your panel, you lose a lot of capability. Nevertheless, these new, integrated boxes now dominate the market and time has shown that they are very reliable. While this is great news for the serious IFR pilot who benefits greatly from the new technology, the pickings are becoming rather slim for the VFR and light IFR pilot whose needs are more basic. Simply stated, avionics manufacturers are emphasizing high-end, state-of-the-art avionics products. Few manufacturers make a stand-alone comm or nav anymore and you can’t even buy a simple, IFR GPS in new condition. Plus, the avionics we’ve depended on for years are aging and are less reliable. As a result, VFR and light IFR pilots are forced to shop in this market in order to equip their aircraft. There are bargains to be found, but there are also “bargains” to be avoided. As in previous articles, let’s start at the top of the stack and work our way down.

Audio Panels and Intercoms

The VFR pilot needs a good intercom. The light IFR pilot needs an audio panel, marker beacons, and an intercom. Though few manufacturers make standalone intercoms anymore, PS Engineering has dominated the intercom market for years and still offers great new intercom options and good support for their used ones. If you can find a deal on a used PS Engineering intercom, go for it! What’s a good deal? A true deal consists of the following: a good unit with current certification, a warranty of some kind, connectors, a mounting rack (if required), and a great price. Take just one of these requirements away and the “deal” can quickly go the wrong direction. Also, know that the difference between the price of new vs. used at this price-point is often minimal, so buying new with most of the above-mentioned aspects of a deal is often the way to go. This is often the case for audio panels too, especially if you need the audio panel, markers, and an intercom. An integrated audio panel with built-in intercom is a concept of the last 15 years. Most audio panels manufactured before that time require a separate intercom. There are good audio panels without intercom in the $400-600 range on the used market. If your existing intercom meets your needs, the King KMA-24 is still a consideration for a new installation. While a little older and on the low end, budget wise, the Collins AMR-350 and the earlier King KMA-20 are also worth considering.

As a rule, I recommend avoiding manufacturers who are out of business and no longer support their products, i.e. Narco, Trimble, and Terra. Remember, however, I’m talking about new installations here. If you have one of these discontinued units in your panel and it still meets your needs, then that’s an entirely different discussion. Should it fail, the investment to replace it will be minimal compared to the cost of materials and labor associated with a complete audio panel change-out, provided you can buy one from a reliable source and at a fair price. Stay away from the Bendix-King KMA-26 Integrated audio panel. King made these for just one year and had a significant failure rate right out of the box—and they’re still failing. Ironically, PS Engineering now makes the audio panels for Bendix-King, starting with the KMA-28.

The light IFR pilot also needs marker beacons for precision approaches. If you’re adding an audio panel and need markers and intercom, any of the earlier PS Engineering models, including the SL series from UPS Aviation Technologies, are a good bet. The SL Series was manufactured by PS Engineering for UPS and was of the same quality. The Garmin GMA-340 is also rock-solid, but as used Garmins go, a deal is harder to find.

Comms and Nav-Comms

As I mentioned, there are few manufacturers who still make new, stand-alone comms, but there are some used units that are worth buying. The VFR pilot is more likely to be searching for a stand-alone comm, but the same rules apply—if the manufacturer is out of business or no longer supports the product, avoid it. You can spend $800 to $1800 for a used comm with the Garmin SL-40 at the high end (and it’s certainly worth it). On the low end, the ICOM IC-A200 is a good unit, but please note that they made both a TSO’d and a non-TSO’d version. Before purchasing the non-TSO’d model, talk to your installer to make sure it’s not an issue in your region. The Bendix-King KY-197 (14v) and KY-196 (28v) are good affordable comms with one potential flaw: the displays in these units, like most of the King line, have been plagued with problems. The displays are reasonable, but they’re being replaced with a new design, LCD display. You could replace the old style display for $300, whereas the new LCD display requires modification and ends up closer to $800 to replace. Bottom line: make sure you’re getting a good display.

There are also a lot of older Collins VHF-251s out there, but if you’re VFR, I wouldn’t recommend these for a new installation. These were actually found in better IFR platforms like the 70’s Bonanzas. If you’re still flying behind the Collins and your budget allows, the VHF-251s can be purchased (tagged and warrantied) for under $500. They too have a display issue, but it’s a little different—each digit is a separate display in itself. Make sure you have a source for these “digits” (Cessna used the same digits). Otherwise, the radios do their job at pretty much “minimum wage.” If you need to add a comm and an audio panel, check out the new PAR200 from PS Engineering. This is the first FAA-certified audio panel with a comm and it can solve both your audio panel and comm issue with a single purchase. If you’re planning to keep your light IFR aircraft for a while, this is an attractive option. (Note: you’ll need to add marker beacons if you don’t have them. The PAR200 does not provide markers, but used ones are available separately and at a bargain price.)

Nav-Comm options on the affordable, used market are in very limited supply, especially in the desirable 14-volt category. The Narco MK-12D Series is no longer a consideration since Narco closed their doors. This was about the only affordable alternative to the Bendix-King KX-155, especially where glideslope is a factor. The older KX-170B/175B units no longer make sense for a new installation. In the case of a failure of your existing KX-170B, I’d recommend the TKM “Michel” MX-170B or C. This is a simple slide-in alternative that eliminates the expense of the install and will give a better return on investment. If you read “Avionics on a Budget” you know what I’m talking about. TKM also offers slide-in options for the Cessna pilot with the old ARC radios in either 14-v or 28-v versions. They cost about $1800 new and can be found on the used market in the $1300 range. You’ll pay $800-$900 for a “good” KX-170B. They are a worthy consideration; and yes, they can be installed as a new installation when budget is a concern. TKM offers a new glideslope receiver and nav indicator that, when combined with a good used Michel Nav-Comm, can save you over $1000 installed vs. the cost of a used KX-155 G/S and indicator. You’ll need to locate used trays and connectors for the TKMs, but these are readily available and usually cheap. The TKMs are pretty reliable and have no known display issues. Plus, they’re made here in the USA.

GPS and GPS-Comms

For VFR flying, you can’t beat the features and value offered by the portables. While Garmin has pretty much driven the competition out of the marketplace, today’s Garmin models are lower in price and packed full of the features that pilots want. You can find some earlier models on the used market and save money, but be sure that the database is still supported and that you get all the “stuff” that came in the original package. If you can, use it before you buy it! I’ve taken used GPS units in trade at shows only to find they had issues later. Panel mount VFR-GPS units are almost non-existent on the new market and make little sense. They cost more, do less, and other than the ability to interface with an autopilot, fall significantly short in the features department.

The IFR GPS market is another story. As mentioned, new products from Garmin (and soon Avidyne) are of the high-end, integrated variety and no one makes a simple, IFR GPS unit anymore. The old, standbys are not aging well and, with few exceptions, are a questionable buy. It makes no sense to purchase an obsolete model for a new installation—especially from a manufacturer who is out of business or lacks support.

The Bendix King models, like the KLN-89B, KLN-90B and even the later KLN-94 make little sense anymore for a new installation. The 89B and 90B are suffering from expensive display failures and a replacement display exceeds the value of the radio. Amazingly, the KLN-94, discontinued only a few years ago, is also having display failures—and, there are no replacements available. In other words, if you buy a KLN-94 and the display fails, you get to throw it away. I think you’ll agree: it’s not worth buying! Therefore, for the pilot seeking a basic IFR GPS or GPS-Comm, about the only consideration is the Garmin 155XL or the newer GPS-400 or the GNC-300XL or GNC-420 with built-in comms. Though all of these are out of production, they’re still supported by Garmin and, as you can imagine, they’re getting a little harder to find. Note, the GPS-400 (IFR GPS) and GNC-420 (IFR GPS-Comm) are the non-WAAS versions. Be careful with the 420; early versions came in 28-volt only and are no longer supported by Garmin. If you’re reading this, you’re probably 14-volt. WAAS is great, but probably a luxury for the pilot flying light IFR on a budget. If you want (and can justify) WAAS, new is your only option and, in my opinion, the only way to go. A deal on a used WAAS unit is rare.


The primary improvement in transponders in the last 20 years was the elimination of the cavity tube (solid-state) and the introduction of enhanced Mode S with TIS traffic. The ADS-B requirement in 2020 will change the game on transponders in GA aircraft, but my general advice there is to hold off—ADS-B options and pricing are likely to improve. In the meantime, you still need to have a transponder and the old stand-by Mode A & C transponder still fills the bill. The older designs are still out there and they all have cavity tubes. When they fail (and they all do), the replacement is significant and approaches the price of a SV replacement. The best example is the King KT-76A. If you have one of these installed and it fails, try to find one with a new cavity tube. You’ll pay a little more, but without the new tube, you could soon be facing the same problem again. If you plan to keep the airplane for a while, the better bet is to look for a solid-state unit like the Garmin GTX-320 or 320A or 327. You’ll have to re-install at about $600-800 labor. The same is true of the other manufacturers like ARC and Collins. Their transponders were equally reliable, but also have the cavity tube issue.

Again, I would avoid Narco. If your Narco fails (AT-50, 150) you can still get the cavity tube replaced, but most other parts are non-existent. Instead, look for a new or used solid-state transponder, depending on how long you plan to keep the bird. Narco actually made a solid-state model, the AT-165, before the company failed, but with no support for the other parts it’s a questionable buy.


While most pilots are no longer using ADF, there are still parts of the world, like Canada and South America, where the ADF plays a role. Probably the best ADF made for GA is and was the King KR-87. If you want to maintain an ADF in your aircraft, the KR-87 is the only one to buy for a new installation. They cost $7500 factory new, so I doubt you’ll want to go there. However, used KR-87 systems are reliable and cost $2500-3000 for the three-piece system, tagged and warranted. This is the only way to go, in my opinion, if you’re adding an ADF to your panel. The KR-87 uses the same display design so watch out there. If you have something else in an ADF in your aircraft and it fails, you can probably find the component you need at a reasonable price. Demand is minimal. Note: If you’re still listening to Rush Limbaugh as you fly on your old ADF, watch your heading. No question, the aircraft will have tendency to turn to the right which, by the way, is not a bad thing in my opinion!


A long time ago, the FAA recognized the IFR GPS as a “legal” alternative to the DME in the IFR system. Nonetheless, it’s surprising how many IFR pilots choose to maintain their DME— even when doing a panel upgrade. Here’s another area where Bendix King has the edge. The King DME models (KN-62, 64, 62A) have been the reliability leaders in the DME arena and stand out as the best option for a new DME installation. If you are adding a DME or replacing a failed one from Narco (DME-890) or Collins, the KN series King models are the only way to go.

While the KN-64 is the most common, the KN-62 (non A) is actually the best buy for the average GA IFR pilot. Not only does the KN-62 have a higher power (allowing for more range), but it also sells for the same price. The KN-62A is the TSO’d model and is required for aircraft flown for hire. It sells for significantly more. Of course, all share the same display issue as the entire Silver Crown line, so take heed.


Ten years ago, the buzzword in GA Avionics switched from GPS to MFD. No question, a Multi-Function Display makes perfect sense in any serious IFR platform. Many models have come and gone since and, frankly, most are not a good consideration on the used market today. The MX-20 from UPS (remember them?) was the first serious player. It was later replaced by the GMX-200 after Garmin bought out UPS. There are no replacement displays for used MX-20s, so avoid them. Conversely, the GMX-200 is always a good investment, provided you can find a “deal” which, as we already established, is always a challenge with used Garmin. The KMD-550 was King’s contribution, but has been discontinued and, frankly, paled by comparison. Avidyne had a series of early models that have since been replaced by the current EX-600. The previous model, EX-500 is worth buying (if you can find one) and the EX-600 is a great choice. Arnav was another early player, but I’d stay away from those too.

Before investing in an MFD, ask yourself, “Why?” If you’re just looking for a large moving map and have no plans to add traffic, terrain, or WX sensors, then your solution is probably a large screen portable GPS. I believe a good portable GPS belongs in every aircraft. Once you’re in the clouds, a portable is equivalent to having a “life raft” for your nav system. And, the more serious IFR you do, the better life raft you’ll want to have. A portable offers many of the features and benefits of an MFD, including WX and Terrain/Obstacle avoidance, at pennies on the dollar as compared to an MFD.

Whenever you buy any piece of used equipment, do your homework and remember the must-have makings of a good deal:

  • A “good deal” is the right solution to your problem or goal.
  • A “good deal” is getting an FAA-certified unit (including appropriate rack and connectors) with a fresh tag and warranty.
  • A “good deal” includes all the above at a fair price!

Again, it’s probably not a good deal if any of these features are missing from the equation. In short, before you buy a piece of avionics, make sure it is worth buying. Questions? Remember, you can almost always find me on the Cessna Owner Avionics forums!

Avionics worth buying (and those best to avoid)

Audio Panels

Worth Buying                                                                        Avoid

King KMA-24, KMA-20                                                       All Narco, Terra, ARC

Collins AMR-350                                                                  King KMA-26

PS ENG SL-10, SL-15

PAR200 w/Comm (new)

Garmin GMA-340


Worth Buying                                                                        Avoid

King KY-197(14v), KY-196 (28v) (displays!)                      All Narco, Terra, Old Val

KY-97A (14v), KY-96A (28v)

ICOM IC-A200, IC-A210

Collins VHF-251 (replacement only)


Worth Buying                                                                        Avoid

King KX-155 (displays!)                                                       All Narco, ARC,

Garmin SL-30                                                                        King KX-170B

TKM Michel MX-170B/C, MX-300, MX-385


Worth Buying                                                                        Avoid

 King KT-76A (replacement only)                                          All Narco, Terra

Collins TDR-950 (replacement only)

Garmin GTX-320, 320A, 327


Worth Buying                                                                        Avoid

King KN-62, 64, 62A (TSO)                                                 All Narco, Collins


Worth Buying                                                                        Avoid

King KR-87                                                                           All Narco, Collins, Terra,

King KR-85, KR-86


Worth Buying                                                                        Avoid

Garmin GMX-200                                                                 Arnav, King KMD-550/850

Avidyne EX-500, EX-600                                                   early Avidyne series

5 Tactical Tips to Contemplate when Investing in Avionics

  1. If the used price is within a few hundred dollars of new, go for the new and get the full manufacturer’s warranty.
  1. Develop a relationship with a good avionics consultant. You’ll know a good one because they’ll listen to you! Their advice and feedback may cost you a few dollars, but it can save you hundreds.
  1. Be realistic about your plans for the aircraft. Don’t spend a lot of money on avionics on an aircraft that you plan to sell in the not-too-distant future.
  1. Before you buy an aircraft, know what you plan to do with it and discuss the avionics in the aircraft with your avionics consultant.
  1. When doing a pre-purchase inspection of the aircraft in which the avionics represent a serious part of the investment, make sure you do a pre-purchase on the avionics too! (You’ll need an avionics shop for this). In a recent Forum thread, I met a pilot who purchased an aircraft without “checking” the avionics. Only later did he find that they were not as advertised in the sales brochure and his unit was not WAAS. This amounted to a $4000 mistake!