Radio Working Poorly

C

Cowboys Air Ranch 84ME

Well-known member
Joined
Apr 24, 2021
Messages
179
Location
Forest Twp, Maine
My 72 Citabria 7ECA has a Icom A-200 Com, and it works great as long as your withing 3-5 miles of airport or other aircraft. When a greater distance is made, it either has no reception of a transmission, or the received transmission is so much static, it can not be heard or understood. Outgoing transmission is the same problem.

I tried pulling the squelch on all the time, but no different. Tried turning off the intercom, and tried different headphones as well. No luck! Now I replaced the Icom unit with a known good unit and exact same problem.

I'm located in northern Maine, and radio shop will not even look at it (Guess I need to install a glass panel) for them to consider any work. Other radio shop in Maine closed all together. Any ideas on what to troubleshoot or how to go about it? Thinking antenna cable/antenna or both? Antenna mounted on right wing root just above door.

This should be a pretty simple and straight forward operation. Just an intercom attached, NO Audio Panel, or multiple radios. Antenna connectors look good w/o any corrosion, also the tray connectors look good. I hate to throw parts at it, but replacing antenna first may be option, then cable if the antenna swap does not work. I am sure it will be something simple, at least I am hoping it is.

Any Suggestions, Advice, Help????
 
Make sure the antenna coax is not RG59 from Radio Shack.

You need RG 58U or its modern replacement RG 400.
 
Clean up every connection from radio to antennae plus the antennae to aircraft attachment.
I have an Icom IC-200 that was working when removed if you want it, send prepaid package and it's yours.
 
Ron86654 said:
Clean up every connection from radio to antennae plus the antennae to aircraft attachment.
I have an Icom IC-200 that was working when removed if you want it, send prepaid package and it's yours.
Click to expand...
Howdy RON86654,

I would love to have a spare, even a non working unit for parts. Do you want to just put it in a US Mail Flat Rate Box and send it that way? I can mail you a prepaid box if you wish, or just wire you the money (PayPal, etc).

Greatly appreciated. (207) 538-7583 Ken "COWBOY" Winiarski
 
Cowboys Air Ranch 84ME said:
Howdy RON86654,

I would love to have a spare, even a non working unit for parts. Do you want to just put it in a US Mail Flat Rate Box and send it that way? I can mail you a prepaid box if you wish, or just wire you the money (PayPal, etc).

Greatly appreciated. (207) 538-7583 Ken "COWBOY" Winiarski
Click to expand...
I am really lazy and since I am giving away, I would like not to have to do any work. If you will send me a prepaid box already addressed I will put my radio into it and put it in the mail box. PM me and I will send my address.
 
Check antenna mounting for good clean grounding.
Check antenna cable for cuts,nick or gouges in the run. Replace if it has any tight bends or kinks.
Check voltage at the radio. Anything less than 12 vdc is problematic.
Check to insure the ground strap going from the engine to the airframe is in good condition and is clean and tight.
Has the radio been working ok and just started acting up?
The fact that you put a known good radio in and had the same problems leaves the power, grounds or antenna at fault...
I'm betting on either the engine/airframe ground or a poor ground to the radio tray itself...😷
Good luck with the troubleshooting.

Chris
 
Nothing more aggravating than a dysfunctional radio. I hate talking on the radio as it is. Any issues with function make me even less likely to use it.

But I love spending other people's money. So my advice is get a GTR 225. :)
 
Big Ed said:
Nothing more aggravating than a dysfunctional radio. I hate talking on the radio as it is. Any issues with function make me even less likely to use it.

But I love spending other people's money. So my advice is get a GTR 225. :)
Click to expand...
Howdy,

Remember, I fly a Old Citabria, 115hp, wood spars and held together by Chicken Wire and Duct Tape.

I do not think I will be spending much on another radio, mainly due to lack of funds. Besides, Fuel for flying is better way to spend money.

COWBOY
 
Did you check your cable? Is it clearly stamped RG58U ?

If not, expect a dramatic improvement when you match impedances.
 
Bob Turner said:
Did you check your cable? Is it clearly stamped RG58U ?

If not, expect a dramatic improvement when you match impedances.
Click to expand...
Howdy,

I have not had a chance to work on the aircraft lately. Now they are calling for more rain here in northern Maine again. Will try to get to it this weekend or early next week.

Have it in the big community hangar at the big airport, so I will be dry, but it is dark, cold and damp. Where did them summer days go?

Also, No "Northeast STOL Series" competition this weekend,..... I'm not happy. I like going to them Fly-in's. Oh well, always next season.

COWBOY
 
Howdy Everyone,

Update: We looked into the wiring, and found no problems at any of the connections (Radio and Antenna). It looks like the grounding plane is good, but was suggested it could be bigger? We still have not checked the cable for anything else besides sharp bends, chafing and OHM's resistance.
The IA is borrowing a tool to check cable further, but suggested that I replace cable anyway since it looks original form 1972. I should replace with 400 series cable or something like that.

I have a friend who may have an antenna that fits that I could try. He is shipping it up here from Connecticut this week. I will let everyone know how I make out as this may help out someone else, once we figure out the issue.

"COWBOY"
 
Checking with an Ohm meter doesn't tell you much with RF. Usually, cables are marked clearly every foot or so - look for marking.
Proper check is impedance at the center frequency. I believe that should be 50 Ohms. A VSWR check can be done with proper equipment.
Sounds a lot like a Radio Shack coax.
An infinite ground plane is theoretically best, but almost anything hooked to the metal parts of the airframe will do - even a small ground plane works (note the size on your hand held).
Finally - an antenna needs a clear view. Having a second antenna (or a gear leg) within a couple feet will distort the pattern. A really good location is on the top wing to fuselage fairing.
 
Bob Turner said:
Checking with an Ohm meter doesn't tell you much with RF. Usually, cables are marked clearly every foot or so - look for marking.
Proper check is impedance at the center frequency. I believe that should be 50 Ohms. A VSWR check can be done with proper equipment.
Sounds a lot like a Radio Shack coax.
An infinite ground plane is theoretically best, but almost anything hooked to the metal parts of the airframe will do - even a small ground plane works (note the size on your hand held).
Finally - an antenna needs a clear view. Having a second antenna (or a gear leg) within a couple feet will distort the pattern. A really good location is on the top wing to fuselage fairing.
Click to expand...
Howdy,

I do know that measuring the OHM's is nearly useless, unless I were looking for a dead short or open circuit. I think my IA did mention getting the SWR meter or something like that.

The antenna is mounted on top between the fuselage and wing. Not sure where else would be better, but this is where it is.

I am trying to get the little things done before my end of October Annual inspection. More I do now, less I do then.

COWBOY
 
If you do replace the cable use RG400/C17 double shielded coax (the gold colored stuff).
If you weren't on the other end of the planet I'd make you one...
Don't forget to check the engine to airframe strap...
 
Hiperbiper said:
If you do replace the cable use RG400/C17 double shielded coax (the gold colored stuff).
If you weren't on the other end of the planet I'd make you one...
Don't forget to check the engine to airframe strap...
Click to expand...
good to know, i'll order some this week. can the ends be crimped on in the plane or does it have to be done on a bench?
 
Has anyone ever heard the saying, "When it rains, it pours?" That's how I feel today.

We unzipped the headliner to access the antenna cable further, and found it goes up the front right post, across the top to the left side, makes a loop, then crosses across again to the right side front, and then to the antenna mounted on the right wing root.

Basically, someone put a extremely long cable where a 4 foot cable would of fit perfectly. Might of been a temp replacement years ago that was never properly addressed. Maybe what they had on hand at the time or antenna originally mounted elsewhere.

Oh well, that is not the problem I am referring to in this post (New problem has nothing to do with the radio).

In our endevors, we found that the left wing fuel tank has a leak, a good leak from bottom. Must of been that way for some time (Lots of interior staining in the wing), but a long story made short, I have to remove the left wing tank now. Boo Hoo,.... Going to start the annual a little early I guess.

Any suggestions how to remove 18 gal tank from 72 7ECA with wood spars? Thinking could cut fabric, and remove from top, and re-fabric over tank once welded?

COWBOY
 
Should be in the maintenance manual? Edit: section 8-2 and 8-3. Looks easier than the Decathlon, which is a giant pain.
 
Last edited:
You must log in or register to reply here.
Back
Top