TKM/Michael MX12 Issue

[CT-Pilot]

Yes, I know it's old. However, the plane I bought recently seems to be receiving Nav signals fine as I can hear the morse code identifiers if I turn the volume up. The CDI (Narco VOA-8), however, doesn't budget at all regardless of where I am in relation to the VOR. 1st step is checking wire continuity from the navcom to the CDI.

Assuming no issues there, does anyone know if any of the King (KI201, 203, etc.) or other CDIs are compatible with the TKM MX12 radio? I imagine there is no plug and play/slide in replacement (such as the TKM radio was for the original Narco 12A it replaced years ago) - but just wondering if any others will work. Doesn't seem like buying another ancient Narco VOA unit would be a wise use of money.

Thanks in advance for any guidance,

 

[Llewtrah381]

I have a TKM 170 I picked up used when I thought my MAC 1700 had died. Turned out it was the audio panel, so I put the MAC back in and the TKM sat on a shelf until a friend needed one and I sold it to him. He ended up having problems with the Nav side, similar to what you describe. I bought it back and sent it to Bevan Aviation, who repaired the loose/bad wires and solder joints for $450. They said that’s a fairly common problem for the TKMs: their “build quality” isn’t ideal.

You may consider sending it to Bevan for checkout. TKM also repairs them, so that’s another option.

If you have access to another working TKM or Narco, you may consider swapping them out to see if it’s the radio or the indicator.

HTH

 

[CT-Pilot]

Thanks. Bennett Avionics is renting me a loaner so I can do just that - will check to see if it is the radio or the indicator. They said that it is most often an issue with the radio getting the signal out to the indicator. So even though I can tune and identify the signal, it is not then getting it back out to the indicator.

 

[CT-Pilot]

So it's not the radio - either wiring or indicator issue. Guess I can test for wiring continuity relatively easy enough. A replacement indicator I'm up in the air about. From what I am hearing, it has to be one of the compatible Narco VOA indicators (-4, -8, etc.) and the King, Mid-Continent, etc. won't work with that radio. Not sure I want to lay out a few hundred for a repaired/functional 40-year old CDI vs just saving up and upgrading to a newer package overall. This bird is a ways off from being IFR ready, so no rush on getting a functional navcom I guess. Portable GPS/iPad can keep showing me how to get there!