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4RNB

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4RNB
If it matters, this is regarding a Cessna 172. It is equipped with
Garmin 340 audio panel
Two G5s
A Vizion Trutrak autopilot
Two King KX155 nav/com radios- one with glideslope, one with VOR
Garmin GPS 175
Garmin GTX 275 transponder (no ADSB in)
I keep foreflight open.

I've had the plane since December. The former owner said the next thing he would have replaced would have been the radio(s).

I flew with a many hour pilot that prides himself on avionics understanding, he though radio 2 worked better than radio 1, thought he could not get as good reception as he expected.

When I have flown with flight following I have not noticed anything. Once near KOKV I could not here them well, they gave me a new frequency that was better. I thought it was no big deal.

My CFII had some modest frustration today, we had a tough time hearing Center, new frequency was not given. CFII agrees that perhaps radios could be replaced.

I'd like to be wise and prudent if and when I replace radios. As things stand, this is the forever plane. If the stock market Gods show favor upon us, we would consider an upgrade, perhaps only after a commercial license and much more time. In the back of mind I have penciled in a paint job (one year) and 180 HP upgrade (when the engine says so).

I am a bit confused looking at the Garmin product lineup. It looks like radios alone could be just over 4K for the GTR 225s. Up from there there is a 5K unit the GNC 255, but for dual radios that price would be doubled, so 10K just for basic parts. At that price point the whole new GTN 750Xi seems a no brainer for 15k parts, but only if it can work as dual radios and dual nav. But this is a horribly slippery slope that then begets more upgrades...and more upgrades.

I'm reaching a point where I think it might be prudent to buy new radios for IFR flying.
What else should I be aware of?
How many hours labor are involved with such things?
 
Get some radio checks with approach control in your area. If they're receiving you fine, and you aren't having any trouble talking to tower or on CTAF from 10 miles out, chances are your radios are fine. The next time you're having trouble "hearing Center", take note of your altitude, and ask for a different freq.

If it were me, I'd hang onto those Kings until I'm ready to spend the big bucks, or they finally do die (whichever occurs 1st). WIth your set up, if I were gonna replace radios right now, I'd get the GNC-255. Even If I just replaced 1 radio, I'd keep the better of the 2 Kings, and get one GNC-255 with a clean install, new coax and antenna.
 
You could get the GNC-255 now, and get a GTR-225 later. You'd have dual com, IFR GPS, and a radio navigator. That's plenty of avionics for a 172.
 
Another bit of cheap debugging is if you can get access to the BNC connectors and try cleaning them both at the radio and antenna. if you have a friend into ham radio they might have an antenna analyzer and likely will help help too.

this thread on overhauling the 155 might be helpful. https://www.pilotsofamerica.com/community/threads/kx155-repair.123419/

Moving to an in panel GPS navigator is spendy, but also opens the door to many more approaches and can couple to your autopilot too.
 
I will be the second to recommend a GNC255 and a indicator to go with it if yours won't work. That will give you a good radio for ILS and VOR approaches and be reliable.

I am using all Garmin in my 172. The 650 and 255 radios are 10X better that the original ARC 385. First I got the 650 and kept the com/nav1 as my com/nav2 385. It was then I realized how better the garmin stuff is. A few weeks later the 385 nav2 quit working. Then I had the GNC255 and new indicator installed. Now I can tune both of my navs for an ILS or VOR approach and have both running at the same time.


Nothing worse than trying to fly with poor radios, been there done that. Good luck.
IMG_0306.JPG
 
Do both radios act the same? If not, you could try swapping antenna leads from one radio to another. Could be the antennas, cable, or connectors (as mentioned above).

I love the KX155s, nothing wrong with em.
 
In general folks think the 2nd radio works better. I think center was similarly static on both 1 and 2 today.
 
Before you go replacing radios, I'd have the antennas & coax thoroughly checked by a radio shop. And determine whether the problem is truly the radio or is interference from another device.
 
wsuffa said:
Before you go replacing radios, I'd have the antennas & coax thoroughly checked by a radio shop. And determine whether the problem is truly the radio or is interference from another device.
Click to expand...

Is a radio shop an avionics shop or a special and different shop?
 
BTW, you might take a look at the "V is for VOR" thread here on PoA for one of the things that can happen to old coax and cause a receiver problem - that can also happen to com radios.
 
@4RNB obviously needs a new plane.

Don't waste your time or money on 172 that can't even receive simple radio communications.

On the other hand, you could go with a GTN "fill in the blank" Really expensive equipment is often the preferred answer to fixing something. Q: hey, my radio needs some work. A: GTN750 is only 15k + labor

I'm a bit of a miser... talk to a avionics guy and get the problem fixed without shopping.
 
I have a King 165 and find it to be as reliable as my Garmin 430w. As others have suggested, have your antennas and cables checked. Make sure that your cables have been upgraded to RG400. You will have to do this anyway if you decide to get new radios.
 
I have KX155's in my 68 Cardinal FG, they started to get a little scratchy. Sent one at a time into Bevan Rabell (https://bevanaviation.com/our-company/) to have overhauled. Some of the KX155's have capacitors that go bad and need to be replaced. Mine came back like new. They are strong xmit and receivers now. I also have a 73 Cardinal RG that has the GNC255 and GTR225, they are great radios. I purchased them thru (https://avionics-laf.com/collections/garmin) check their sales prices. The GPS 175 is a great WASS navigator, when wired to the GNC255 it gives a lot of options. I also have a gramin xponder with a tail beacon for ADSB OUT.
 
I had trouble with my KX125 one day. Got reports of garbled transmission. Found bad coax. replaced it, and just fine from there.
 
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