Is there such a thing as an affordable nav/com? Mine has a somewhat annoying buzz in the background.

I have currently have a MX300 Nav- Comm

Any suggestions for a replacement?

Nav/com?
Nav/com/gps?

Thanks.

Yes there is, you have it already. The TKM's are a great economical replacement radio. Most issues are the 40 plus year old installation for the original ARC radio. Have you cleaned the terminals on the tray and checked the coax cable ends? Have you adjusted the radio squelch? (hole for a jeweler's screwdriver) I bet the issue isn't the radio itself, if it is I would send it to TKM for a check up. The TKM's are the economical replacement radio, hold your breath for anything else.

Thanks for the reply. I just bought this plane and obviously have some sleuthing to do!!

I've read the pamphlet twice and couldn't figure out how to adjust the squelch. I'll look for it and start with that because it seems like a squelch adjustment would fix the problem to me.

Tony

Arctic Flyer wrote:Thanks for the reply. I just bought this plane and obviously have some sleuthing to do!!

I've read the pamphlet twice and couldn't figure out how to adjust the squelch. I'll look for it and start with that because it seems like a squelch adjustment would fix the problem to me.

Tony

I'd suggest pulling it and cleaning the contacts first. Radio Shack has a good contact cleaner that cleans without damaging anything.

Cary

I had a 300 in my old 172, never had to adjust anything, bought it new and replaced the ARC. Just put new MX 170c and MX 12 into my 182 and had to adjust squelch on them. Looking at the manual for the 300, just looks like sidetone and mic are adjustable on the rear, no squelch adjustment. Ensure the nav volume is turned off all the way. i would pull the radio, clean terminal strip and slide it out and in a few times. Play with the audio panel, go from one com to both and see if it affects it at all. Next would be headset/plugs. Unplug the handheld mic if still in plane. I would call TKM on Monday before going much further, they now have new owners that actually answer the phone and are very helpful. Good luck!

Mark Y. wrote:I had a 300 in my old 172, never had to adjust anything, bought it new and replaced the ARC. Just put new MX 170c and MX 12 into my 182 and had to adjust squelch on them. Looking at the manual for the 300, just looks like sidetone and mic are adjustable on the rear, no squelch adjustment. Ensure the nav volume is turned off all the way. i would pull the radio, clean terminal strip and slide it out and in a few times. Play with the audio panel, go from one com to both and see if it affects it at all. Next would be headset/plugs. Unplug the handheld mic if still in plane. I would call TKM on Monday before going much further, they now have new owners that actually answer the phone and are very helpful. Good luck!

I had a really nice conversation with the new owner at OSH, Ken Beckemeyer, 2 summers ago. Nice guy, came across as honest and forthright. He was formerly the CEO of AmSafe, the seatbelt maker. He had just bought the company a few months earlier, and he expressed that his immediate goal was to improve service to customers. I understand that he has succeeded in that endeavor.

Use that Radio Shack cleaner, and clean everything that moves--headset plugs and jacks, hand mic plug and jack, connectors at the back of the navcoms, etc. It's amazing how a little gunk can screw up a perfectly good radio.

Cary

We used to also use an eraser on the male pins when I was in the repair shop for a couple of large Silicon Valley companies.
Voltage regulator grounding has been known to cause similar noise.
Alternators usually have noise suppression capacitors that can go bad
Intercom squelch can get in the way.
Putting an OLD 2 contact (pin) headset into a 3 pin socket for
headset WITH mike can even shut down the system - Solution
Just pull the 2 pin plug out one "notch" and headset will listen. Co-pilot side.
Might be a stereo vs mono. thing.

Running a generator?

Nuff for now

^ All of the above. I had some similar issues, and while I haven't fully resolved them due to some wiring I just need to re-do, simply cleaning things out helped a good bit. I pulled both of my radios and the audio panel since they were all tray mount, and went to work on them for an evening. I got into all of the connectors with contact cleaner and various implements (q-tip and a soft brush work pretty well), and also cleaned the rotating selectors and other potentiometers. Basically if it moves, the metal wipers in there get oxidized. Get some contact cleaner in there and rotate them fully several times. Blow it out and then let it dry the rest of the way before you turn them back on. If you're slightly ambitious you can pull the faceplate for better access, just be mindful that it's exposed circuitry at that point and sensitive to static. That's a good time to take a lens cloth and wipe the accumulated dust off the display and inner cover surfaces you can't normally get to.

At minimum you can remove and insert tray mounted radios several times just to try and wipe the metal contacts clean through friction, but if you have an evening, do yourself a favor and actually clean them properly.

Just doing that on mine eliminated a great deal of static I was experiencing, and even my strobe "whoop whoop" in the intercom was somehow reduced a little - still not sure how that happened exactly, maybe just a oxidized ground somewhere. Cleaning electric contacts is standard preventive maintenance as these planes age, regardless of where you keep it.

Arctic

Are you still running a generator?

Is the noise level constant - consistent - or does it vary with eng. speed.

Do you have a 4 place intercom - some rear seat folks
end up with the squelch down till it sounds like an open mike hanging out the door.

Do the listening test with no mike plugged in -
just for the hell of empirical evidence of a "clean" start to investigation

Still Curious:

Chris C

No generator.

Consistent noise, does not change with power settings.

4 place intercom and that adjustment does nothing for the real problem.

The noise sounds like staticky Morse code.

Not sure when I'll have a chance to look at this stuff. Still having fun in the plane for sure- just turn the radio down.

Radio shacks and mechanics hard to find up here sometimes.

Do you have wingtip strobes? My strobes made a similar sound in my citabria. They were triple flash, so it sounded similar to Morse code, 3 fast blips at a time.

Sent from my SM-G870W using Tapatalk

Did the old "Ford" regulator box get upgraded to newer lectronic version when switched to alternator? Used to have to burnish contacts in old Ford style regulators.
Never knew enough about how to adjust them.

Burnishing tool is thin like a small feeler guage with find abrasive.
Contacts have to be touching when you do it.
Similar to polishing points in an old distributor.

Still probing,

Chris C

We'll, I'm embarrassed.

Had mechanic friend help me take the radio out. I was a little nervous since I'd never looked at one before.

Radio came out pretty easy and we looked at the business end of it- looked shiny and nice so we reinstalled and discussed next step which was some additional cleaning of headset jacks.

Flew plane next day and the radio is quiet and life is good.

Better to be lucky than good I guess.

A little dirt/corrosion goes a long way to creating problems, right?

Cary