DME is acting strange

[Brett Kallish]

Hi Folks, I have a KN-64 in my 1967 C model that I bought a year ago. The DME only worked once for about 3 minutes. Normally I just see dashes for the read outs but today I unhooked the cable from what I think is the correct antenna connection. I went back into the airplane and the remote[vor] setting had data on it ,not the correct data but data none the less. That lasted for about a minute and then went to dashes. I switched to freq and got a reading for about 10 seconds and it went back to dashes again. I rehooked up the antenna and just got dashes again. Does anybody have any idea if maybe it is the cable or antenna or the KN-64 that is acting up.

 Brett

[Marauder]

Brett -- I had a 64 for a number of years. Were you able to check it on another VOR? I would get what you describing in occasion but it was linked to the VOR and not the DME.

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[steingar]

Deep six the thing and get a GPS.

[Brett Kallish]

 

Marauder, I have 2 vor's and tried both with the same result.

[Marauder]

 

Marauder, I have 2 vor's and tried both with the same result.

If you have been able to verify it with two separate DME sources, it could be anything from the antenna to the unit itself.

Mine has been out for 4 years but if I recall it correctly, putting it in FREQ mode, allows you to tune in the frequency independent of the Nav source (as opposed to moving the switch to RMT). If you have done that and it still shows a problem with different VORs selected, the problem is within the DME, connectors or the antenna. Not sure there is much more you can do other than swapping out the antenna or cleaning the connections.

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[Jerry 5TJ]

You can directly set the DME channel from the front panel of the KN64.  You don't need to get channel info from VOR.  If that doesn't work either then perhaps a bench test at an avionics shop is next -- it is a quick test if they have a DME test set.  

It could be coax, connectors or antenna.  Or...

I had a KN64 that worked intermittently, too.  It would work, then go to all dashes.  Finally I got it acting odd while on bench.  Frequency synthesizer PLL wasn't locked: found under 7x magnification a poor solder joint on SMD chip cap in that area of circuit board.  Once that manufacturing defect was  fixed ( a bit of solder) it was solid for years.  

I recommend you get the box bench checked first.  

Best luck. 

[Brian Scranton]

Mine does the same thing. I brought it to an avionics guy and he said, "You're 430 works fine. Who cares about your KN64?"

[N201MKTurbo]

1 hour ago, Brian Scranton said:

 "You're 430 works fine. Who cares about your KN64?"

I guess he isn't interested in repair work...

[Brian Scranton]

Just an honest fella who knows that the time it will take to repair the unit isn't worth it...I appreciated it!