How to remove a KT76A Transponder & KX170B CommNav

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Doug Snead

New member
Hello all,

I'm trying to remove my KT76A Transponder & KX170B CommNav. I understand how it should work after watching this video:

http://www.eaavideo.org/video.aspx?v=2520157744001

http://bcove.me/zua4l9wx

But neither of mine are popping out when I turn the allen wrench. I even tried slightly pulling on the unit after each 1/8th of a turn. Didn't budge.

Any advice?

Thanks,
Doug
 
After looking around online and talking with some guys on the Yahoo Group, here's what worked for me.

I never wrenched on either one real hard. There were a LOT of warnings about breaking the tabs or stripping out the tab by using too much force.

There were also a lot of warnings about not taking off the faceplate yourself, unless you know how to put the internals back together again.

Both took a 3/32 allen wrench.

For the KT76A, pushing it in slightly helped while undoing the allen screw, turning it (left) as far as it will go and then pull it out. This box did move outward (1/8th to a 1/4 of an inch) as I turned the allen screw, just like in the video links I posted in the previous message.

The KX170B was more of a bear. It took only 1/4 turn counterclockwise, and the box really didn't move that much outward as I turned the allen wrench....maybe 1/16th of an inch. I still couldn't wiggle it out though. One website said King had a special tool to pull against the faceplate sides. So I took a flathead screwdriver and gently pried it out. I twisted the screwdriver against the tray and the back of the faceplate. I took a picture in case anyone tries this themselves, doug_snead at yahoo.com. One website said: "The removal of a King KX 170B from it mounting tray is very critical. Rotate the allen wrench to move the locking tab only 90 degrees counter clockwise from the locked position. The allen screw does not move the unit from its mooring position. Any further travel of the locking mechanism will result in damage to the channeling wafers switches, resulting in a very difficult repair or a non-repairable unit."

The cheapest faceplate I found was $165, but these guys have something for $19, www.engravers.net. I think its a template to help repaint your existing faceplate.

Doug
 
gads, I loved those 170s.. had more than I can count, even one plane with dual units...

but when two different units in two different planes both filled the cabin with smoke, I was faced with getting them repaired. After seeing their innards on an avionics tech's bench, I had enough. I may have a 1950's plane but I'm not going to fly with a 1960s ticking time bomb.

IMHO anyone flying those radios now should:
- Practice flying with the master switch off.
- fly with a backup and,
- Fly with the latch unlockled so it can be yanked in-flight.

Put the repair money towards an SL-30, you'll never regret it. perfect solo unit for a 2-seater, excellent NAVCOM 2 for anything.
Heck, if you're flying with a handheld GPS and don't need NAV, get the SL40 and save money (com only) there's one on eBay right now for 1400.00
 
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