Can you replace a KX-155 with a KX-165?

[MikeOH]

My KX-155 is getting a bit long in the tooth ('crunchy' knobs, a couple of missing segments, occasional 'buzzing') so I'm looking at repair/replacement.  The repair cost and lead-time is getting to where buying a used one (around $2500 from Bennett Avionics) is looking good.  For not much more I can 'upgrade' to a KX-165.  But I have no idea if I can just slide into the KX-155 rack without any issues (like needing a different indicator).

Anyone done this, know for sure?

[N201MKTurbo]

You can. The KX-165 has an internal VOR decoder. If you want to use it, you have to add a couple of wires. If not, just plug in the 165.

[MikeOH]

15 minutes ago, N201MKTurbo said:

You can. The KX-165 has an internal VOR decoder. If you want to use it, you have to add a couple of wires. If not, just plug in the 165.

Thanks!

The VOR decoder is the feature I like....just need to figure out which wires

[AndreiC]

My understanding was that the KX-165 was only made in a 28v version. So unless you have a step up transformer (or plan to install one), I think the answer is no for a vintage Mooney. 

[Ragsf15e]

2 minutes ago, AndreiC said:

My understanding was that the KX-165 was only made in a 28v version. So unless you have a step up transformer (or plan to install one), I think the answer is no for a vintage Mooney. 

This link shows both versions 14v and 28v.  Not sure if tge 14v are available, but tgey seem to have existed at some point.

https://www.seaerospace.com/sales/product/BendixKing/KX-165?srsltid=AfmBOooIJjJzNpuai_Ihsgz2WLXdFiRDQsAOqOxpGk1GsmvH5pN64exp

[N201MKTurbo]

I have a 14v KX-165

[AndreiC]

Oops, I think I confused the KX165 with the KX155A. 

[DCarlton]

17 hours ago, MikeOH said:

My KX-155 is getting a bit long in the tooth ('crunchy' knobs, a couple of missing segments, occasional 'buzzing') so I'm looking at repair/replacement.  The repair cost and lead-time is getting to where buying a used one (around $2500 from Bennett Avionics) is looking good.  For not much more I can 'upgrade' to a KX-165.  But I have no idea if I can just slide into the KX-155 rack without any issues (like needing a different indicator).

Anyone done this, know for sure?

I had my 155 refurbished a few years ago; new display; new lenses; new knobs (the internal plastic parts that create the detents for the frequencies).  It's a great #2 radio now.  And there's NO software.  :>

[hammdo]

I too have a referb kx155, solid radio/nav…

-Don

[Aerodon]

On 7/3/2025 at 5:41 PM, MikeOH said:

Thanks!

The VOR decoder is the feature I like....just need to figure out which wires

I think you are referring to the 'radial indicator' feature.

The KX 155 needs an indicator like a KI209 that has the internal decoder.  The KX165 has this decoder in the radio, and needs an indicator like a KI206.

Last time I looked, I think you can slide a KX165 into a 155 position and it will work.  But not the other way around.

 

Aerodon

 

 

 

[MikeOH]

3 hours ago, Aerodon said:

I think you are referring to the 'radial indicator' feature.

The KX 155 needs an indicator like a KI209 that has the internal decoder.  The KX165 has this decoder in the radio, and needs an indicator like a KI206.

Last time I looked, I think you can slide a KX165 into a 155 position and it will work.  But not the other way around.

 

Aerodon

 

 

 

Yes, ‘radial indicator’

One of my concerns was if the 165 would drive the KI209 that I have, or if I would need to change it to a KI206.

[N201MKTurbo]

4 hours ago, MikeOH said:

Yes, ‘radial indicator’

One of my concerns was if the 165 would drive the KI209 that I have, or if I would need to change it to a KI206.

I pretty sure the KX-165 will drive both indicators. You will need to add some wiring to make the 209 work. I have a bunch of King pins (actually Molex) that I doubt I’ll ever use, if you need some.

[Aerodon]

6 minutes ago, N201MKTurbo said:

I pretty sure the KX-165 will drive both indicators. You will need to add some wiring to make the 209 work. I have a bunch of King pins (actually Molex) that I doubt I’ll ever use, if you need some.

I'm looking at the KX155/165 IM.  If it is wire for a KX155 with glideslope, I am not seeing any extra wiring.  The composite output and G/S wires should already go to the KI209.

If you install a KI206, then yes, the composite output loops back to the other connecter, and a new set of wires to the KI206.

I'm thinking it will work without modification

 

Don

 

 

 

[N201MKTurbo]

12 minutes ago, Aerodon said:

I'm looking at the KX155/165 IM.  If it is wire for a KX155 with glideslope, I am not seeing any extra wiring.  The composite output and G/S wires should already go to the KI209.

If you install a KI206, then yes, the composite output loops back to the other connecter, and a new set of wires to the KI206.

I'm thinking it will work without modification

 

Don

 

 

 

Yep, I had them backwards.

[skykrawler]

On 7/4/2025 at 1:38 PM, DCarlton said:

I had my 155 refurbished a few years ago; new display; new lenses; new knobs (the internal plastic parts that create the detents for the frequencies).  It's a great #2 radio now.  And there's NO software.  :>

Actually, the 155 and 155a are a digital radios.  The have firmware which is a pretty much software.

I think a different indicator (OBS) is required for the 165.

[MikeOH]

2 hours ago, skykrawler said:

I think a different indicator (OBS) is required for the 165.

UGH!  That has been my concern.  It does appear there are opinions, both ways!  Not sure how to be certain.

I may well just buy a used KX-155 if I can't be sure a KX-165 is truly 'plug-n-play'; not worth buying another indicator and rewiring, however minor. I was just hoping to 'upgrade' if I had to buy another radio.

[IvanP]

1 hour ago, MikeOH said:

UGH!  That has been my concern.  It does appear there are opinions, both ways!  Not sure how to be certain.

I may well just buy a used KX-155 if I can't be sure a KX-165 is truly 'plug-n-play'; not worth buying another indicator and rewiring, however minor. I was just hoping to 'upgrade' if I had to buy another radio.

KX-200 is supposed to be a direct "slide-in" replacement for KX 155 or 165 units. I guess that is an "upgrade" option without having to dig into the panel and wiring. My 165 (secondary) is probably on its way out so I may be in the same boat as you. At about 5 AMUs it is not cheap, but worth considering. I am thinking about going thsi route when my radio bites the dust. I definitely do not want to dig into the rats nest behind the panel at this time. I know that we can get cheaper new radio, but the labor cost woud likely exceed the savings.

[Fly Boomer]

2 hours ago, MikeOH said:

Not sure how to be certain.

I often turn to the Bennett web site -- they are typically quite detailed and thorough.

[MikeOH]

26 minutes ago, Fly Boomer said:

I often turn to the Bennett web site -- they are typically quite detailed and thorough.

Doesn't look promising based on what I found on their site: