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KX 155 Nav Comm?

Russ McCutcheon

Well Known Member
It?s at least as old at the airplane, 26 years, Its always great, it has sat in the cold and in the heat for many years, some times the display is a little flaky in extreme cold tell it warms up.

The question of the day is this. The airplane (RV-4) sat on the ramp at Hillsboro OR for maybe 2 hours wile we visited the county fair across the street. Came back the radio worked fine and we left the towered class D field but when I went to change frequencies the numbers to the right of the decimal would not change, same for both the comm and the nav, and adjusting the hole numbers to the left of the decimal would also change the numbers to the right of the decimal, it was not just the display but the knob adjusting the numbers to the right was definitely not changing the frequency, after turning it off for a very few minuets and putting the plane in the hanger it was fine. Also it has sat on hotter ramps for longer before with no problem and it is being force fed blast air wile under way.

Anyone know anything about this?
 
The display unit is on a card edge connector. These get dirty and corrode. Remove the display unit and clean the contacts.

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KX 155 radio display blinks intermittently, randomly

My old trusty KX 155 has decided to act up lately. The digits of the active and standby radio freqs blink very fast, disappear for a short period, return to normal, go away for a bit etc. Checked the mounting tray. Seems to be snug connection. Does not seem to be related to OAT. Sometimes goes away after radio has been on for awhile.

Any ideas if this is a precursor to failure? If so, can these radios still be repaired??
 
KX-155

William
Thanks for those photos. My KX-155 which is a solid perform has the problem that when I push the flip/flop button the numbers don't swap. If I push multiple times it will eventually flop. Can I access the contacts for that button and clean it like your photos almost show? Or do I have to give it to an Avionics guy to clean. I think it is just oxidation on the contact of the button.
 
My old trusty KX 155 has decided to act up lately. The digits of the active and standby radio freqs blink very fast, disappear for a short period, return to normal, go away for a bit etc. Checked the mounting tray. Seems to be snug connection. Does not seem to be related to OAT. Sometimes goes away after radio has been on for awhile.

Any ideas if this is a precursor to failure? If so, can these radios still be repaired??

Yes but the cost of repair is often equal to the purchase price of a good used unit.
 
William
Thanks for those photos. My KX-155 which is a solid perform has the problem that when I push the flip/flop button the numbers don't swap. If I push multiple times it will eventually flop. Can I access the contacts for that button and clean it like your photos almost show? Or do I have to give it to an Avionics guy to clean. I think it is just oxidation on the contact of the button.

You might consider installing a remote flip/flop switch per the install manual.

http://aeroelectric.com/Installation_Data/Bendix-King/KX155_IM.pdf
 
If you decide to remove the display to clean the contacts, be careful not to crack the glass. These are gas filled and segments may not work if the gas is released.
 
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