One more time Trig are set to steal the market from right under Kings nose !
Trig could make a fair bit of money if they cleverly ate the crumbs left behind by firms who just want to push products forward or who have melted down.
They would make a packet by doing a KLN94 plug replacement which does LPV and is PRNAV approvable. There are many thousands of them in use and the LPV capability would instantly sell in the USA.
A KX155 (non-A) replacement with 8.33 would be clever too. Countless thousands of those in use.
Trig are however selling transponders to Avidyne and King. There was a thread on it here. They make a basic transponder board which others are putting a custom front panel on. So they probably don’t want to piss off these “easy business” OEMs too much by going for the big time.
Both the non A and the A version have lots of display problems, as well as other Bendix/King avionics that uses these orange/red displays. It seems that aircraft outside suffer these problem the most. If you unable to read the display, the radio is worthless. I never seen this problems with other manufacturers.
I think the King displays were the only cheap way to make sunlight readable alphanumeric displays back in those days.
Electronics is my business, since the 1970s, and the state of the art option (dot matrix LED displays – like this but bigger than 0.2") were too pricey and even today are probably around €20 1000+. Whereas gas discharge displays are a few €.
“The question remains: why replacing a KX 155A with a KX 165A,…..”
Maybe I did not understand something but for me the answer is that the KX 165 A has 8,33, the KX 155 A has not. The No. 1 KX 155 A drives the HSI.
Since I had no problems with Bendix radios about ten years and my impression is that these are high quality radios I did not opt for Garmin or others. But the main reason is that both radios should be easy to change due to the same rack, this is what the avionics and the dealer said. I have already checked the connectors, they both have the same on their backside. On the front side the only difference is 8,33 instead 25.
This is probably a peripheral discussion, but the KX155/155A radio cannot directly drive an HSI – well not the KI525.
The KX155/155A outputs the lateral data (VOR/LOC) as a “composite” signal. (Sometimes, in avionics, this is incorrectly called “composite video” which is bollocks – composite video is a completely different thing.) This is a demodulated version of the VOR/LOC VHF signals and is fully in the audio band. Normally you have another box tucked away somewhere (often a KN72) which converts the composite signal into voltages that drive the HSI deviation bar, the TO/FROM flags, and the NAV (no valid signal) flag. To do this for a VOR, the KN72 needs to have the HSI course pointer position fed to it.
I don’t think any of the old-type HSIs accept composite directly, though an EHSI such as the SN3500 does (and massively reduces the wiring and the calibration effort). The KI204 CDI also accepts composite directly.
If you are into heavy reading of 1970s electronics (interesting stuff though if like me you like analog) I can give you all the maintenance manuals 
The KX165/165A has (in effect) the KN72 built in. But very few planes use that part.
Obviously if you pull out a 155/155A and push in a 165/165A then the latter’s VOR/LOC converter will be unused.
But the radio part should still work as before, and that is the mystery.
As I wrote previously, there might be something in the KX165A configuration options which affects its composite output. The 165A’s manuals are here and I welcome anybody to have a look at the IM and the config options. I am running around a lot now so can’t do it, and I already spent a few hours on the one I put in 2-3 years ago.
the answer is that the KX 165 A has 8,33
Of course, that is the only reason for installing a 165A over a 155A.
Well, you might do it to dump the KN72 but the cost of the rewire by a standard avionics shop would make that pointless.
For a TCAD system, I understand the need for a heading input as these targets are relative to own ship heading and position
Actually the TAS boxes (except the base TAS600 one) can all use GPS track for that purpose, which in flight is perfectly good enough – the wind offset is usually a lot less than the azimuth error 
The heading input was originally put in for helicopter applications, where the heading could be anything whatever, relative to the GPS track (and the GPS track will vanish, or be rubbish, if you hover). Avidyne claim that using the ARINC429 heading gives you a faster resolution of moving targets… I already had the data (from the SN3500, which got it from the KG102 via XYZ, and output it on ARINC429) so it was used for the TAS605. Now the TAS605 gets it from the SG102 directly.
The display on most king radios require quite a high voltage to operate and the usual problem is not the display or the display driver, it is the contacts between the display and the unit that get small amounts of corrosion on them and increase the electrical resistance, cleaning these contacts will usually revive the display.
The display on most king radios require quite a high voltage to operate and the usual problem is not the display or the display driver, it is the contacts between the display and the unit that get small amounts of corrosion on them and increase the electrical resistance, cleaning these contacts will usually revive the display.
True, but for a flying club for example it requires them to ask an avionics shop to clean contacts. That adds costs to using this radio. I have seen flights delayed or cancled due to this display problems. I would say that it’s a weak point in the design of these radio’s. So I can imagine that people call these radio’s junk. I think so myself as well, at least for aircraft which are not hangered. They are just not up to the job when an aircraft lives outside.
Also the dealer in US confirmed an easy replacement due to same connectors. What is true ? Can the exchange harm the new radio, the HSI or any other avionics ?
It depends on the exact P/N, there are a lots of different -dash numbers which are not all pin compatable, be sure either you or your avionics engineer knows what you/he is doing. Be sure to at least check which -dash number you want to take out and want to install, and be sure to find out about the difference. Just that it has the same 18 / 25 pin connector doesn’t garantee same pinout.
They are just not up to the job when an aircraft lives outside.
You could say that for nearly all GA avionics.
I am in electronics and have designed loads of stuff that has to work outdoors, and the approach is totally different. Basically the avionics in a GA plane parked outdoors is more or less guaranteed to get internal corrosion. It’s just a question of how long it takes and whether you sell the plane before the item fails. Some GA stuff has conformally coated PCBs (the KS27xC autopilot servos for example) but this is rare. I have not yet seen a cockpit item which is thus protected.
Considering the pricing, the stuff is built really cheaply. It is mostly a 1970s way of building electronics, with some eye wateringly pricey Positronic crimp-contact connectors ($2/pin so easily $100 per connector) thrown in.
A few years ago I thought about building a KX1x5A plug compatible radio for the replacement market, using modern methods, sealed electronics, DSP technology, and with a nice dot matrix LED display. I decided it was a dying market, with fierce dealer loyalty making the market impenetrable and with the most juicy new business going to radios contained in GPS receivers.
Back to the KX155A replacement, I see SE Aero= offer this
so they list only one relevant version; the -0201. How can one go wrong replacing a KX155A with that?
On the KX155A they list this
i.e. again only the one relevant version. The one I replaced was the with-GS one, yet the -0201 165A did not drive the KI525 HSI.
A few years ago I thought about building a KX1x5A plug compatible radio for the replacement market, using modern methods, sealed electronics, DSP technology, and with a nice dot matrix LED display. I decided it was a dying market, with fierce dealer loyalty making the market impenetrable and with the most juicy new business going to radios contained in GPS receivers.
That was probably a wrong assessment and you might have built a nice business. Even when branding is a hurdle, there is always the way of selling your core to the empty shell US avionics companies. With the 8.33kHz IFR mandate you would have sold loads and be in a good position for a lot more to come when the rest of the fleet has to meet the 2018 requirements.
Lots of companies did their KT76 Mode-S replacement but nobody jumped on the 8.33kHz market which should even be larger because Mode S until today isn’t even mandatory in all EASA countries unlike 8.33kHz.
Back to the KX155A replacement, I see SE Aero= offer this
Have a look at the “delivery” column. The market of used/refurbished/overhauled KX-165A-201 is empty. It already was about 6 months ago when I considered this upgrade but then decided to play chickens game with the German regulators and won — for now (one 8.33kHz is being tolerated in .de).
I agree that most avionics are not coated, and not designed for outdoors use.
I don’t agree that all avionics are sensitive to this. Standing outside gives sometime problems, altough I have never seen any Garmin with these problems, even the 15 year old ones. Neither with Bendix King KLX, KMD, KY and so on with other displays. And also no other corrosion related problems with the KX-155/KX-165.
It is realy the amber HV display on old AND NEW (!) Bendix King equipment that gives problem. When they would have use an LCD just like on the KY series, the wouldn’t have encounterd this problems, and it would have been a better design.
Have to cancel a flight because you can’t read the COM/NAV frequency or the distance on the DME, or the frequency of the ADF is a big fail in my opinion.
I must admit that the LCD display is harder to read then the bright amber HV displays.
That was probably a wrong assessment and you might have built a nice business. Even when branding is a hurdle, there is always the way of selling your core to the empty shell US avionics companies. With the 8.33kHz IFR mandate you would have sold loads and be in a good position for a lot more to come when the rest of the fleet has to meet the 2018 requirements.
I guess so. It is not to overlooked how expensive it is to develop avionics. Our company does some, and must says that is quite expensive. Unfortunatly because the non certified markt seems to have lots of nice avionics products for a much better price. With strict regulations it is quite hard to become a major player. I think Trig is the only one who is becoming a major player (from Europe).
Lots of companies did their KT76 Mode-S replacement but nobody jumped on the 8.33kHz market which should even be larger because Mode S until today isn’t even mandatory in all EASA countries unlike 8.33kHz.
Don’t agree, most KT-76 replacements where too late as well, I have done a lot, but most were not certified and delivered on time. The same is / will be true for VHF COM. It just takes a lot of money and time to certify.
Even when branding is a hurdle, there is always the way of selling your core to the empty shell US avionics companies
One of the issues with that is that you have to set up the whole QA charade, including hosting a delegation of FAA employees.
One can see why companies like Dynon go after the non-CofA market. You don’t even need ISO9000 (another €€€€ charade, traditionally discharged by throwing in a QA “consultant” for a few weeks).
I have had dealings with some US empty-shell companies (Honeywell/King comes to mind) and I would end up tearing my hair out. The place is stuffed with pension-counting old geezers and has been for more than a decade. The smaller players like Shadin are the same…
how expensive it is to develop avionics
A KX165A is about 1 man-year, if you are competent in analog and RF and are not “leveraging” (a word I dislike) an existing product. The user interface could be done with a 4004
I am certain the hardest thing is getting into the dealer (installer) pipeline – in the CofA market where customers might read big colour adverts in the aviation mags but without help and co-operation from the installer they will never buy it.
I must admit that the LCD display is harder to read then the bright amber HV displays.
My GTX330 was unreadable in daylight and had to be swapped for another one. There was a problem with it, but it isn’t very good and IMHO works because one rarely looks at it.
LCDs were around in the KX155 days (I designed some products with graphic LCDs in the mid 1980s) but had (and have) problems with the temperature range which really needs to go down to -25C for cockpit gear and back then I don’t think that was possible. Some GPSs have heaters behind the LCD display.
It just takes a lot of money and time to certify.
That is another often published claim from the big names, which I really don’t believe
A player like King could bring out a new radio or transponder in 6-12 months after starting the project. I think the long “certification” times we hear about (Avidyne being the most notorious example currently, with their IFD boxes) are just a smokescreen for most of the able people having left the company – because they had nothing new to get their teeth into for a decade or so. Any company will have the same problem. Clever technical people hate to end up with a rubbish CV; the Linked-In people are very pro-active
