I have a KN64 DME in my Comanche which has worked well, while I've had it. Last spring, it noticed that it wouldn't always let me switch to the Freq. change page and select a new VOR Freq. I assumed the switch was going bad. This summer I had some new radios put in and I had the installer check out the DME. He took it out and bench tested, it worked fine. He said the contacts on the switch were a little worn (corroded, not sure) so he replaced the switch. He tested in aircraft and it worked. I took off and headed home and was messing with it. It worked for about 30 min and then was doing the same thing. I took it back to mechanic. He bench tested, everything working. He put in plane, everything was working. He checked the tray and everything seems to be in good working order with the connections, etc. It worked on the way home.

Fast forward. With my new GTN 650, I have gotten started on my Instrument Rating. We got done with basic attitude and were ready to try some approaches. Instructor says, Tune DME to VOR. Guess what? It won't let me change the frequency. It is just stuck on the one I was on last.

Does anyone have any ideas on what would cause this?

Now to throw in another wrench. The KN64 can be remotely tuned using the primary nav radio. When we were shooting approaches at GLD, the DME was actually giving me info from GLD. I'm wondering since we had the NAV tuned to GLD if that automatically tuned the DME to that freq. (I'm not sure what freq. I had entered the last time the DME worked, it could have been GLD) My question is, Later in the approach, the NAV was tuned to the LOC freq, and wouldn't I want my distance (DME) to be measured from VOR.

I'm sure everyone is now confused, and I know I am. If anyone has experienced something like this let me know as my avionics mechanic and I are a little baffled.

Nate

1st caveat - all avionics panels are different

The way ours is wired is there is a switch that toggles the DME between the #1 VOR input and the #2 VOR input. It also has a setting to allow us to manually tune the VOR on the DME itself.

You might also want to use the Garmin simulator - if they have one for the 650 to do some ground school practice. If the King folks offer a course on the use of the 650 I would buy it. We used both of these tools to learn the 530W when we had it installed.

BTW the 530W has a built-in DME and if an instructor told me to tune the VOR, I would be doing it on the 530W not the DME and the 530W would give me the DME distance - bet the 650 has these same facilities.

P.S.

We all went through this learning curve so ask away. Hopefully we can help even though our panels may be different

Pat,

Thanks for the response. I have used the Garmin 650 simulator, but it is for the 750 which is a little different (same basics).

As far as the DME funtion, I know the 650 will fly a DME arc, but I haven't found the capability to be used as a DME while I'm using the radio for the ILS.

Nate

Nate, that function should be there, I just don't know that piece of equip well enough to tell you where to look for it.

Nate, is your KN 64 stuck in the "hold" position?

Jay

It acts like it is stuck in the hold position. It doesn't seem to matter when I move the switch around. It gives me blank lines on the freq page, but I cannot enter a new one.

Nate

Way back when before I had new Nav/Com radios installed the new King DME sat below the original MK 12 Nav/Com. On a summer day with that MK 12 operating the temperature inside the radio stack woud get hot enough to cause the DME to malfunction. Is it a temperature problem?

Miller 45P

Shouldn't be a heat problem, the DME is located left of the pilots control yoke. It is not in my main radio stack. Don't know why, that is just where it's always been.

Was up the other day with A/P running, so I had a few minutes to mess with it. The DME works great on the remote setting. The problem is that sometimes the NAV is tuned to the localizer, but I need DME measurements from the VOR.

If I put the switch to the Freq. setting and wait (like 20-30 seconds) most of the time it would let me tune in a frequency. Then when I switch to gs setting and wait (20 seconds) it will gives me the info to the VOR. It doesn't always let me change the freq. Doesn't make sense because it seems like a switch problem, but my avionics shop put a brand new switch in and it works perfect on the bench. We have had it out twice and when you switch to freq. it lets you immediately change the freq. As soon as I take off, it doesn't want to cooperate, but it is working somewhat. Just don't want it to not work when I go for my instrument checkride, or in the real clouds.

Nate