KY-197 squelch adjustment

[A64Pilot]

Mine is pretty much constant broken squelch, making it just about unusable.

Twice it’s been bench tested and supposedly squelch adjusted, but when reinstalled the problem persists, I don’t think paying for a third try will fix the issue. I don’t think it’s always broken squelch but to be truthful I haven’t really used the thing due to the squelch issue so I can’t be certain. Only use it to listen to ATIS etc.

On removal and looking at the exterior there appears to be two different squelch adjustments. I haven’t touched either yet because I’m not sure why there are two.

Anyone know what the two different squelch’s are?  Which one to adjust? I also assume clockwise adjustment would increase squelch?

[N201MKTurbo]

Is the volume knob pulled out?

[A64Pilot]

No wish it was that simple

But the plot thickens, I went out to pull the radio to just look and did something I never do, turned the battery then the Avionics switch on, with the radio installed of course, and inside of the hangar.

Both radios were broken squelch.

Engine running the 430’s squelch operates normally, so now I’m confused. Squelch was broken on both radios whenever the pins were pushed in, selecting one radio or the other made no difference, only thing that did was volume on each radio did function and turning a radio off made it silent.

So now I don’t know what to think, Wx is supposed to be really bad until Mon so I can’t go out and see if running the engine makes a difference, but for the last three years it has, so I suspect it still will.

Is my audio panel bad somehow?

Plane stays on a battery minder so battery voltage was I’m sure above 12V, probably about 13 but I didn't check.

Hangar has LED lights so I don’t think that’s it, but didn’t check, maybe they are that noisy?

[A64Pilot]

Went out and left the lights off, turned off the dehumidifier and disconnected the battery tender and tried again.

This time only the KY-197 was broken squelch, so something is in fact noisy enough the break squelch on the 430, I assume it’s the lights but haven’t tried to see what it is.

So I’m back to needing to know what the two squelch adjustments do. I guess I could try trial and error but don’t want to cause a problem

[A64Pilot]

Further digging has me believing the two squelch adjustment pots are Carrier squelch, and Carrier / noise squelch, they are marked c squelch and c/n squelch.

I can find neither a decent definition of the differences of each, nor the adjustment procedure for them

[PT20J]

See if this helps.

http://www.mikeg.net/hobbies/aviation/avionics/combined/King KY-196-197 Combined.pdf

 

[N201MKTurbo]

http://www.mikeg.net/hobbies/aviation/avionics/combined/King KY-196-197 Combined.pdf
 

Here is the service manual, it tells you how to adjust the squelch. I have a Cushman CE-5 service monitor, if you were around here, we could set it up properly.

[N201MKTurbo]

5 minutes ago, PT20J said:

See if this helps.

http://www.mikeg.net/hobbies/aviation/avionics/combined/King KY-196-197 Combined.pdf

 

Jinx

[N201MKTurbo]

5 minutes ago, PT20J said:

See if this helps.

http://www.mikeg.net/hobbies/aviation/avionics/combined/King KY-196-197 Combined.pdf

 

Jinx

 

I have an inspection due on the Mooney, I should head out to the hangar instead of laying on the couch and screwing with Mooneyspace….

[A64Pilot]

Well I’ll tell you what I did prior to seeing the links, I adjusted after marking so I could return it, the C/N squelch 1/8 turn, squelch was not broken, so I kept turning it back towards the original setting by a fraction checking, it’s now just barely above original setting, edge of the screw is beside the sharpie mark denoting the original setting.

Still no broke squelch, Wife came out and announced Breakfast was ready, which means I had better stop what I’m doing. I’m going to go out and try the hangar lights, if they break squelch I’m calling it good until I can fly and test, based solely on they seem to make the 430 break squelch

[A64Pilot]

56 minutes ago, N201MKTurbo said:

http://www.mikeg.net/hobbies/aviation/avionics/combined/King KY-196-197 Combined.pdf
 

Here is the service manual, it tells you how to adjust the squelch. I have a Cushman CE-5 service monitor, if you were around here, we could set it up properly.

Thing is it was set up properly on the bench, twice. Guy who did it was old school, now retired but was a master on these old avionics, he would even repair the old Century autopilots, they apparently have a long ribbon with components on them and he would lay this ribbon out on a long table testing until he found the fault. So I think he was very good, but sadly now gone.

I assume something in my airplane is noisy and it takes a smidge more squelch than the bench setting, but the 430 doesn’t have the problem and it works fine, never have to turn squelch off to hear a transmission.

Went out and conducted a Redneck test, it IS the Chinese LED hangar lights that breaks squelch on the radios, they are on two circuits split roughly half and half, on the 430 both have to be on to break squelch, on the 197 now either or both break squelch making me think squelch is set a little less than on the Garmin.

[A64Pilot]

1 hour ago, N201MKTurbo said:

http://www.mikeg.net/hobbies/aviation/avionics/combined/King KY-196-197 Combined.pdf
 

Here is the service manual, it tells you how to adjust the squelch. I have a Cushman CE-5 service monitor, if you were around here, we could set it up properly.

Unfortunately it only tells you how to set it up on a bench assuming you have proper equipment, no “field” adjustment that I found.

[Fly Boomer]

8 hours ago, A64Pilot said:

Thing is it was set up properly on the bench, twice. Guy who did it was old school, now retired but was a master on these old avionics, he would even repair the old Century autopilots, they apparently have a long ribbon with components on them and he would lay this ribbon out on a long table testing until he found the fault. So I think he was very good, but sadly now gone.

I assume something in my airplane is noisy and it takes a smidge more squelch than the bench setting, but the 430 doesn’t have the problem and it works fine, never have to turn squelch off to hear a transmission.

Went out and conducted a Redneck test, it IS the Chinese LED hangar lights that breaks squelch on the radios, they are on two circuits split roughly half and half, on the 430 both have to be on to break squelch, on the 197 now either or both break squelch making me think squelch is set a little less than on the Garmin.

To be clear, are you saying your hangar lights are noisy in the audible frequency range?  Or maybe they are emitting an RF signal?