KX-170 starting to fail?

[bradp]

Interesting issue.  KX-170b is older than me.  Nav and com receive functionality just fine.  During a flight I’ll slowly lose transmitting ability until it just plain doesn’t work. Takes about 1-2 hrs - but I don’t think I’ve needed to transmit on com2 in such a long time that I’m not exactly sure when the box started failing.  

I’m thinking it’s something internal to the box (likely) or there’s some sort of static build up issue (unlikely).  No issue on com1 box.  No difference in clear or wet weather.  

Thinking about getting a spare first and then figuring out whether it’s worth taking a different path.  I have a GI-106A laying around, so I’d probably replace with a digital box of some sort ie SL-30 used or maybe a 255-A. Both those could present a second presentation on a HSI through a GAD-29B, which is nice but not sure whether I’d ever use the functionality.  

Thoughts or advice? 

Thanks

brad 

[ArtVandelay]

Could it be overheating? Check behind it that the air vents are clear and pull the radio, blow some compressed air into it to remove dust accumulation.


Tom

[Marauder]

I had two KX-170Bs when I first bought my plane. They are excellent radios - when they work. Mine became troublesome due to the plastic cam failures. You have several options:

- find functioning units on eBay. They should be fairly common and cheap. Pick up a couple and swap them out as they fail.
- buy a Michel MX-170B slide in replacement. Either new or used.
- pick up a later model used radio
- buy a new 255A or 255B
- buy an Icom, Becker or other manufacturer unit.


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[Jerry 5TJ]

Assuming you have a KX170B there’s a repair guy named Glass who still repairs those antique King radios:

KX170B

I see he now only works during the summer.  

[xcrmckenna]

My kx170 had issues, the volume on the nav side didn’t work very well. So I couldn’t ID a vor or loc. I went the route of buying another 170. They are cheap, till I ended up with three radios all with different issues and not able to use. They came from Mooney Space, Beechtalk, and another from EBay.

I ended up sending my original 170 and the best of the three to Pacific Coast Avionics. They swapped the volume pod from the spare 170 onto my original one. All good now. I wasted a lot of time dealing with used radios that are like you said older than you..... I would contact PCA, or go the route of a new MX170.


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[Igor_U]

I had a similar issue couple of years ago.

It turned out to be intermittent on-off switch that I never used... Issue was diagnosed by a shop on a field when I took it to them and repaired in a day for nominal fee.

I've considered to mail it ot Glass (link above) as he repaired and indicator years ago but according to his website, he works only couple of months a year.

Good luck.

 

[bradp]

Quick follow up:

Found a seemingly decent, apparently working KX-170b on ebay.  High SN, faceplate good.

Nav works perfectly

Com issue - a few frequencies seem to receive better on a 0.25Khz above what it should be (i.e. ATIS is 119.90 and I'm hearing it better on 119.92).

Is this more likely to be a wafer alignment issue or a crystal alignment issue.

Need to get my Mrs to come to the airport with me with a handheld so I can see if this is limited to a low mid or high frequency block.

Any recommendations for getting it aligned/tuned?  Kx170b.com seems to be the go-to but not open until June.

Thanks much,

Brad

 

[N201MKTurbo]

7 minutes ago, bradp said:

Quick follow up:

Found a seemingly decent, apparently working KX-170b on ebay.  High SN, faceplate good.

Nav works perfectly

Com issue - a few frequencies seem to receive better on a 0.25Khz above what it should be (i.e. ATIS is 119.90 and I'm hearing it better on 119.92).

Is this more likely to be a wafer alignment issue or a crystal alignment issue.

Need to get my Mrs to come to the airport with me with a handheld so I can see if this is limited to a low mid or high frequency block.

Any recommendations for getting it aligned/tuned?  Kx170b.com seems to be the go-to but not open until June.

Thanks much,

Brad

 

Clean the channel selector rotary switches. The problem is you need to remove the face plate to do it right. it takes a bit of talent to reassemble the knob gearing to the switches. It took me a while to figure it out.

You could probably get it going by just rotating the knobs a bunch of times in both directions to scrape off the oxidation.

[bradp]

My old one has a broken rotary gear selector so I have one to practice with :-)

[Marauder]

53 minutes ago, bradp said:

Quick follow up:

Found a seemingly decent, apparently working KX-170b on ebay.  High SN, faceplate good.

Nav works perfectly

Com issue - a few frequencies seem to receive better on a 0.25Khz above what it should be (i.e. ATIS is 119.90 and I'm hearing it better on 119.92).

Is this more likely to be a wafer alignment issue or a crystal alignment issue.

Need to get my Mrs to come to the airport with me with a handheld so I can see if this is limited to a low mid or high frequency block.

Any recommendations for getting it aligned/tuned?  Kx170b.com seems to be the go-to but not open until June.

Thanks much,

Brad

 

Brad -- as an owner of two venerable KX-170Bs, they were great radios -- when they worked. I had fairly regular issues with the tuning mechanisms. I know back in the 90s there was something the FAA sent out about the requirements for 720 & 760 comm channels. Not sure if it was related to the 8.33 spacing but I remember a number of guys scurrying because they had 360 channel versions. I eventually slipped a MX-170B in one of the slots which was a welcomed addition.

Good luck on keeping it alive! The guy at 170B.com is the only one I know who still claims to work on them.