So why is the KX165A an ancient radio ? Please tell me.
Take a look at the Maintenance Manual. The cornerstone of the receiver, the IF strip, uses a TDA1572T, a Philips chip. I found its datasheet dated 1992, and the end-of-life information on the NXP home page.
The synthesizer chip (Fujitsu MB1504) also seems to be out of production, at least Fujitsu’s product search does not find it.
It is also interesting to note that the whole VOR decoder is done as an analog circuit (using the venerable HEF4046 PLL chip I still remember from my early youth, but at least that one still seems to be in production). Nowadays one would do that digitally, which would be cheaper and one would not have to worry about microphonics.
So Peter is right, that design must be from the eighties, or early nineties latest. Forgive me if I consider that ancient, I earn my money in consumer (and industrial) electronics, which has a somewhat compressed timescale. In aviation, 80ies is probably still modern if one considers that most aircraft vendors still have designs from the 60ies of the last millenium as their current product lineup.
I could turn this around and ask why would you fit two radios with audio amps into ans aircraft that already has an audio amp in the audio panel ?
Simply because the components for the audio amplifier are cheap (BOM maybe 1$US), but product versions are expensive. So it is more economical for Garmin and its customers to have one product that fits both use cases, even if the audio amp is not always used.
I found both chips on Ebay in a few minutes. Honeywell and other repairers will have stock, and Honeywell probably bought a huge number of them years ago.
The KN72 decoder is also wholly analog (4046). However the 165A uses some digital pots for adjustments, which is better than trimpots which are notorious for long term issues.
Yes, it’s a stupid design today (presumably you would do the whole radio as a direct digital design, with a fast A-D right after the antenna amplifier?) but appropriate for the era.
These radios last well, by 1980s/90s avionics standards. The VFD displays give trouble eventually but it seems to happen due to moisture more than anything else.
The KX155/165 emitted a lot of 11th and 13th harmonics, trashing GPS reception. The “A” versions were a lot better but they still do it a bit. I had to fit notch filters on mine, and it looks like the DGAC GPS certification was basically skipped (definitely not IAW AC20-138).
Re the audio amp, doesn’t the non use of an intercom (“audio panel”) make the whole system sensitive to the characteristics of the headsets e.g. two different brands of headset used concurrently, not working together? I have flown in many such planes and none of them worked properly. Wiring the mikes and the headsets in parallel is such a bodge…
So the KX165A does the primary task well, the technology is mature but available and in some installations it will be a slide in fit.
It is then the case that some who have King equipped panels may find it more economic to use the KX165A, so why the rush for another radio just because it is new ?
With the price of renewing certified equipment in aircraft I would consider that the modern trend to scrap anything within a few years of service would have been something to avoid rather than something to aspire to.
The reason the KX165A’s have been removed from my aircraft is I am currently in the position to do a major rebuild and want an Avionic fit that will last 25 years………. That should see my flying out !
If I was looking ten years ahead there would be no question of removing the KX165A but it is not physically posable or operationally sound to keep them and have panel space for dual RNAV system.Re the audio amp, doesn’t the non use of an intercom (“audio panel”) make the whole system sensitive to the characteristics of the headsets e.g. two different brands of headset used concurrently, not working together?
Old audio panels where just switch boxes, either each radio supplied it’s own speaker driver amplifier, or in other cases, where no speaker output was available, 500 Ohm audio was routed to a radio with an aux input, which was amplified in the LF amplifier of the radio.
Nowadays all modern intercoms have separate outputs, also to enable crew isolate for example, while keeping a group available for passangers.
Just an update in case anybody finds this. Not every KX165A made is 8.33. You have to order P/N 069-01033-0201 and the -0201 is the important bit.
Also, when trading in a KX155A, this may be relevant and it means that you may not get a decent price for the KX155A unless it is S/N 24100 or higher.
This may also be applicable.
A lot of people ask me about this… and for a KX155A slide-in replacement this is an obvious option. Especially for an N-reg; a Minor Mod, no question at all.
What is the cheapest way to generate an EASA-1 form for an overhauled KX165A purchased from the USA with an 8130-3?
I realise that if bought from say South East Aerospace in Florida, you get a dual release 8130-3 which AIUI is good for an EASA-reg plane.
Peter
Remember EASA now has CS-STAN making this a very short paperwork exercise to change boxes.
That’s great but you still need to get the EASA-1 or a dual-release 8130-3 before the CAMO will accept it, if it is the (substantially cheaper) overhauled or used unit.
And some CAMOs won’t accept anything but an EASA-1 for anything whatsoever, which is simply wrong. I know one IFR tourer owner who is totally over a barrel on this. Unfortunately the references are not easy to find…
I can’t understand why anyone would not understand the use of a Dual release 8130-3, what part of dual release do they not understand ?
For EASA-reg you have 4 options
Obviously the last two above (used parts) are restrictive for EASA-reg owners because the vast majority of smaller shops in the USA are not accessible to them.
For N-reg you have 4 options
For “radio” you can substitute any other part (engines and props are different AFAIK).
Where the hell the latest references are I don’t know. I recall @wigglyamp posted on this topic a few times.
There is a table in the bi-lateral TIP Rev 5 which provides the specific requirements on equipment release for N and EASA aircraft (I can’t link to it from my phone!). Peter’s post above is incorrect on what releases are required and who can issue them. For new equipment, the Form 1 or 8130-3 is always issued by the manufacturer in the case of TSO’d equipment. For used parts the issue of a single or dual release will depend on whether the approved organisation has both FAA and EASA approvals. A EASA Part 66 can’t issue a Form 1 – it has to be either a Part M subpart F or a Part 145 organisation.
A CAMO is not the one concerned with equipment release – it’s the certifying person/approved organisation installing the part.
