A_and_C wrote:
Likewise the later DME systems are highly reliable unlike the earlier systems.
Agree on that. If there are budget constraints however I would leave that part of equipment installed.
I would definitely have a DME.
The ADF is worth keeping, and as A&C says the KR87 is a good one (arguably the only reliable GA unit ever) but whether I would install one today is a good Q. You cannot legally (yeah I know people will debate this) fly an NDB approach without carrying an ADF even though everybody smart will actually fly it with a GPS. Whether this matters to you will vary; Europe is full of NDB approaches and these will “never” go away (a) because they exist (b) because an NDB is cheap to keep going (c) it is the cheapest way to have an “IFR” airport which is a requirement for most AOC ops. But for local flying it may not matter.
A single GNS430 is fine for IFR enroute and GPS/LNAV approaches. Jesse – am I right in that it is a Minor mod if there is no AFMS authorising approaches? If true then one may as well put in a GNS430W or a GTN650 and wire it up to the autopilot properly so one has full capability including coupled ILS and LPV but not legally.
With the cost of KR87 system on the second hand market putting one in to an aircraft is not a bad investment to stay leagal on a lot of missed approaches ………………… And you can get the BBC news.
Peter wrote:
the KR87 is a good one (arguably the only reliable GA unit ever)
I find it hilarious that you mention “reliable” and “ADF” in the same sentence; that said, I never had a problem with my KR85 so far (maybe I’m just lucky…), so if the OP’s KR85 works ok, I wouldn’t spend any money in upgrading the ADF (maybe apart from the huge amount of panel space the KR85 takes), especially as the ADF is mostly a regulatory fig leaf. Even in the east and south east, where there had been tons of NDBs say 5 years ago, they’re rapidly disappearing. In switzerland, there’s only 1 NDB left, and not because it is needed, but because reportedly a number of FI complained that without it they could no longer train NDB holds 
It seems to me that the UK is the last holdout.
A_and_C wrote:
I am sure that if Garmin believed they could improve on the current DME systems they would.Garmin clearly think both the King DME & ADF units are up to the mark because Garmin products are designed to integrate with them.
Your arguments don’t make any sense to me. I’m pretty sure Garmin could make a DME better than the KN62a. They don’t do it because they think the return on their investment isn’t worth it. Both ADF and DME are legacy systems, in a shrinking market. Nobody in the US, by far the largest market, needs an ADF or DME anymore (at least for noncommercial ops). There are probably more second hand units on the market than potential buyers, so you’d have to compete against a second hand unit. It’s only a few tiny markets like europe who still need DME… In contrast, there’s still a lot of progress in the GNSS world. You can set yourself apart from the second hand market by bringing new features to the market, like WAAS/EGNOS, better UI, better maps, SynVis, and hopefully more frequency bands (L2, L5) and more GNSS systems (Glonass, Beidou) in the future.
And it also makes sense to interoperate with the legacy DME/ADF products, because it’s easy to do for them and their customers in the smaller markets that lag behind need this.
Nobody in the US, by far the largest market, needs an ADF or DME anymore (at least for noncommercial ops).
That’s certainly not true in Europe and I don’t think it is true in the USA if you actually comply with the alternate airport planning requirements (which I guess many don’t because most SR22s don’t have a DME).
I find it hilarious that you mention “reliable” and “ADF” in the same sentence
The KR87 is reliable because the antenna assembly is potted in epoxy. That used to be a major failure point.
No ADF is accurate in indicating the bearing to the NDB where the situation is “wrong” e.g.
Otherwise, an ADF can be about as accurate as a VOR.
In a modern plane, it should not take up panel space because an EHSI can display the needle when needed
Tomjnx
So you own the last operating KR85 !??!
Twenty years back I was having trouble supporting my KR85 ownership despite a shed load of spare parts and access to a very good box fixer. About five years back the last KR85 was removed from my fleet and the two boxes of spares went in the dustbin. Since then ADF troubleshooting & box changing has stopped with the KR87’s performing very well and giving no problems at all.
Looking at it from a commercial point of view I think it would have paid me to replace all the KR85’s twenty years ago as the labour and money spent maintaining the KR85 vs a new KR87 fit would have been a close run thing but saved the disruption.
Your operating KR85 flys in the face of all the statistics both electrical and by now mechanical ( because the last four or five units I had failed mechanically and no parts could be found) . I’m not saying I don’t believe you…….. Just you are incredibly lucky to have a KR85 that still works.
The KN62 & 64 on the other hand is the most reliable Avionic unit I have ever owned I first owned one of these in 1985 and apart from changing the lens and a bit of paint on the front of the unit they have seen no maintenance whatsoever. We shal have to see how my KN63 gets on in my latest Avionic upgrade.
While I agree that the market for ADF & DME is shrinking and Garmin building a new ADF would make no sence whatsoever Building a new DME would have needed a looking at ten or so years back if you were Garmin. I would guess that due to the reliability of the KN 62,63,64 units it was seen as unnecessary as it would have been difficult to build a better unit and Garmin are in the best place to judge as all the people with Avionic design talent walked across the street from King to Garmin years back due to the frustration in dealing with Allied Signal / Honeywell bean counters who completely destroyed the dominant market position that King had in the GA Avionic market.
A_and_C wrote:
We are talking in comparative terms, the aircraft in question was fitted with a King KR85 ADF, the King KR87 is light years ahead of the KR85 with some of the later versions having a Superflag output for integration with EFIS systems.
What does a “Superflag output” do?
Airborne_Again wrote:
What does a “Superflag output” do?
It is flag switching using the positive side (positive power). This is uncommon, common method is to switch the ground line.
A_and_C wrote:
So you own the last operating KR85 !??!
Sure there are enough operating KR-85 in the field. Especially if the equipment has always been inside, and regular used. The KR-87 does fail as well, and IMHO seems more reliable as it is from another era, so in that point, sure the KR-87 is more reliable.
The main advantage is the limited panel space for the KR-87. Though with a working KR-85, and not having a need for panel space, I would just keep the KR-85. It would be just wasting money.
Jesse wrote:
It is flag switching using the positive side (positive power). This is uncommon, common method is to switch the ground line.
So the “super” doesn’t refer to any functionality but only to the electrical protocol?
Peter wrote:
Otherwise, an ADF can be about as accurate as a VOR.
I am very sure that a perfect ADF receiver operating in theoretically optimal but practically never existing conditions can be about as accurate as a shagged VOR receiver operating in the real world.
ICAO Doc 8168 Table I-2-2-2 specifies the tolerances (2 σ) as follows:
Ground Systems: VOR +-3.6°, NDB +-3°
Airborne Systems: VOR +-2.7°, ADF +-5.4°
Flight Technical: VOR +-2.5°, ADF +-3°
So ICAO thinks a VOR receiver is twice as accurate as ADF, and they also think the pilot can more accurately follow a VOR radial compared to an ADF bearing
It seems the KX155 doesn’t quite achieve that, they specify +-3°.
The KR87 spec also says +-3°, but doesn’t say at how many σ.
Peter wrote:
In a modern plane, it should not take up panel space because an EHSI can display the needle when needed
I wasn’t talking about the indicator, but the receiver box. Unless there’s a remote capable version of the KR87 out there which I don’t know about, you still need panel space for the receiver box (with the orange high voltage gas discharge displays…)
A_and_C wrote:
So you own the last operating KR85 !??!
If you say so I’ll take good care, so as soon as I don’t need it anymore, it can go into a museum
