King KMA24 Marker Beacon problem

[lvflyer]

I got a chance to get out to the plane today so here is what happened and I'm still baffled. I checked the connections to the antenna and KMA24 and all seemed tight and clean. I took off on 13 asking the tower ot allow me to cross the OM(TUNGG) 31 approach at 1500 feet. No tone or light. I had them vector me directly over TUNGG several times because my ADF is old and think has bitten the dust. It is original one for 1968. Anyone know an ADF that will fit in a round instrument hole? Anyway I then had them vector me to ADLER which is OM for 13 and as I approached the airport environment I began to pick up first the MM tone then closer I got the MM light on my way to ADLER where I got the OM light and tone. I climbed to 6000 feet and made a pass over ADLER where I got tone and light on high Sens and none on low sens and passing by airport environment I got tone and light for MM on high sens and none on low sens and was vectored once again to TUNGG and no light or tone. I asked tower if anyone else had commented on this condition and the answer was no. Passing over TUNGG at 6000 yielded no other result. I am perplexed.

[Frank Giger]

I'd think that forty-three years is an outstanding life cycle for any electronic part.

[whemme]

lvflyer,

That ADF you have in your panel that fits in a round 3-1/8" hole is a King KR-80 ADF. It is the only ADF that I am aware of that was ever designed to fit in an instrument panel hole rather than in the radio stack. A newer replacement ADF that will fit in that hole does not exist and getting your present KR-80 ADF repaired is problematic due to its age.

I agree that it is a puzzle as to why your OM tone and blue light works on the ADLER outer marker but not at the TUNGG outer marker.

By the way, I would not necessarily expect your marker beacon receiver to receive a usable signal at an altitude of 6000 ft. You may or may not get the tones and light at that high altitude but the normal altitude to cross those marker beacons at KPIA is 2400 ft or 2500 ft depending on whether your are on the ILS 13 or ILS 31 approach. The received signal strength will be a lot less at 6000 ft versus 2500 ft.

[lvflyer]

Thanks. I am aware of the altitude, but I figured if I could pick up the signals at that altitude then the equipment is sensitive enough. As to the ADF I do have a non useable ARNAV Loran in the copilot side. I've seen some old ADFs that might fit in that hole, because I doubt if I'll ever have an IFR aproved GPS installed when the hand helds can do so much more for much less. So what models do you think would slip in there. Can't very well do an ILS where an ADF is required for waypoint identification.

[whemme]

lvflyer,

It is not clear to me if you are talking about the avionics rack space now occupied by your ARNAV Loran-C receiver or the 3-1/8" instrument hole now holding your existing non-working King KR-80 ADF receiver. If you are talking about the instrument hole, the only ADF ever designed that will fit there is the KR-80. So, if you want a working ADF in that hole, then you must find some avionics shop that can still possibly repair that old ADF.

You don't say whether you have a panel mounted GPS in your Mooney or not; but assuming that you don't then I have a suggestion if you want a GPS and a newer replacement ADF system. Remove the ARNAV Loran-C system (which I assume is probably a ARNAV R-20) which is probably mounted in the right side avionics stack. That R-20 I believe has a mounting height of 3.25". In that space, you should be able to mount both a used King KR-87 ADF Receiver (which is 1.3" high) and a 2.0" GPS receiver. The King KR-87 ADF system in my opinion was the best ADF system ever designed. It consists of the KR-87 ADF Receiver, the KI-227 ADF Indicator and the KA-44B Combination ADF Loop/Sense Antenna.

You existing KR-80 ADF system consists of the KR-80 ADF Receiver/Indicator, a seperate long wire sense antenna and a KA-42 or possible a KA-42A Loop Antenna mounted on the aircraft belly. All of that would have to be removed to install a good used KR-87 ADF system.

Now some possible choices for a 2.0" high GPS receiver follow:

1) Garmin GPS-150 or GPS-150XL - these units are VFR only GPS receivers
2) Garmin GPS-155 or GPS-155XL - these units are IFR approach recertifiable GPS receivers but are not WAAS capable.
3) King KLN-94 - this unit is a IFR approach recertifiable GPS receiver, non-WAAS capable.

I recommend avoiding either the King KLN-89 VFR or King KLN-89B IFR units due to a history of very expensive display problems.

If you choose one of the IFR systems, then remember it must be installed with it an associated CDI (Course Deviation Indicator) which will need to be mounted in an available 3-1/8" instrument hole - you may or may not have an such a hole available. If not, and depending on what brand and model CDI you already have in your panel acting as your existing #1 VOR/ILS or #1 VOR/LOC, you may be able to share that CDI with an IFR GPS using a NAV-1/GPS switching system.

Just some ideas to consider. I love spending other people's money!

[lvflyer]

Thanks for your suggestions. Since the plane is pretty much a hangar queen and is only used when needed, rarely, I am not able to justify an in dash GPS. Since the LORAN system was decommisioned I purchased an Anywhere Map GPS that does everything the Garmin does except being certified as IFR and cost about a third of the Garmin. So I'm not any worse off than with the LORAN. My concern is with the ADF. I think all my KR-80 needs is cleaned since I can pick up radio stations, but the tuning is scratchy and I can't pinpoint which signal is the ADF. I know it is ancient, but in this day and age the ADF seems to be disappearing like the LORAN system. I would love to spend the money on a complete glass cockpit, but I am pretty sure I would never get that money out of it when/if it sells. In addition I know, for example, the G-1000 system in the CAP planes raised the annual expense to almost $20,000 a year. I certainly cannot justify that for a 68 Mooney. As to the Marker Beacon I am still perplexed. Sent a message to Bloomington Aviation with no response so not sure of my next step. The only thing I can think is the marker beacon frequency are within a tolerance that does not coorespond to the tolerances of the KMA-24 and thus one of th ebeacons is outside of the reception tuning of the indicator. If that is the case then the indicator needs to be recalibrated.

[Bill Greenwood]

I have a King KR 80 ADF, non working. I don't know of any shop that repairs these. I bought it from one of the big shops that sell used avionics and advertise a lot. After going to some trouble and expense to get in installed in my cockpit that is pretty short on room for avionics it would not work and the co would not take it back and give a refund, claimed too much time had expired, and they could not get parts.
I'd like to know if anyone has parts and can repair it. It is a neat looking package.