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Only Sometimes,and Then Not For Everybody!


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I have this radio problem, maybe....Last weekend I was doing circuits in my Jodel at Tyabb. Another aircraft in the circuit gave me a bit of a serve about garbled transmissions, "unreadable " he said. So, of course, I landed and had a look at all connections, nothing, all ok..... After a bit of reading on the 'net I fitted a power supply filter and some "beads" (all recommended by Microair)... Yesterday I tried it out, reception was as clear as a bell ".Vastly improved" I asked for radio check and got "Great, 5x5" from an Europa. Then in the circuit I got another "unreadable reception" message, Maybe from the same bloke?...So what is going on? I rang Microair and the very helpful guy said to check the antenna and co ax cable..I will replace them. I spoke to Melbourne Central on another matter a week ago and he never said a word about bad transmission. ..But .Do I have a problem or don't I ???.............Can I tell/ask the complainer to get His radio checked.? How can I tell if I am transmitting OK....

 

 

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If it's the same guy I'd suggest he's got the problem. You've obviously had a few verification's it's OK so I wouldn't rush out & do something radical. If it happens again, I'd try talking to another AC or ask Melbourne Centre if they can read you when he complains & see what they say. Radio's can be a pain though with intermittent probs. I'm not a techie btw, just played with various 2 ways since the first CB's came here.

 

 

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Just get someone on the ground to check it for you, maybe call the clubhouse or a handheld when you are airborne.

 

I've definitely experienced issues from specific radios to specific radios so not surprised. Perhaps MC can offer further comment, it's about tuning and there's probably not much you can do about it if it's not your problem!

 

 

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Guest DavidH10

We all have tose problems when we talk to people who won't admit they have a problem... just everyone else. No joke, these people do exist. I'd suggest that you have ample proof that your radio is transmitting fine. See if you can interest the other pilot into doing some tests on the ground, where you can hear how your radio sounds through his and also that of an independent radio. If s/he is willing, it shouldn't be hard to determine which radio is in need of some attention.

 

 

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Guest aviatrix27

Testing on the ground is sometimes of no value - I had a problem with one of my radios, everyone was reading everone else "5's" while on the ground, but in the air I had the sounds of silence. It turned out to be antenna related. Just saying it's not ALWAYS a valid test.

 

 

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Guest Michael Coates

The only way to properly test the radio is on the bench with test equipment. There are other test you can do while the radio was in the plane but they are only a third of what can be done on the bench.... I agree with Kaye that testing on the ground is not always a valid test because there are so many other issues like vibration as one example that can make a huge difference between the quality of the transmission and reception on the ground versus in the air, one example comes to mind where the coax cable wasn't crimped correctly and on the ground with the engine at idle everything seemed to work properly but in the air with the added vibration it gave an intermittent ground to the coax and that of course cause problems.

 

The problem could also be with the other aircraft that is reporting your radio as being faulty. VHF radio equipment was probably installed on the ark ! it is a lousy system but unfortunately we are stuck with it. One of the joys of making VHF work properly in aircraft is to make a station which is close and transmitting sound about the same volume as a station that is 50 or 100 miles away. To do this we use a feature called AGC (automatic gain control) and this smooths out powerful stations and boosts quite stations so you are effectively hearing the same audio in your headsets all the time. AGC circuitry can occasionally have problems and it could be that your radio is simply overpowering the other aircraft which is in close proximity. Without their AGC circuitry operating correctly you would overpower their radio and come in garbled and unreadable whereas at the same time they could be talking to somebody 50 or 100 miles away without any issues because the AGC is not being overloaded.

 

I have tried to explain this in plain English without getting complicated with the big words (which even I don't understand but just repeat parrot fashion from the technicians). Hopefully you understand that the problem may not be with your aircraft but it may be with the other aircraft reporting the problem. The only way to find out is to test the radio on the bench and then test it again in the aircraft before use. This requires usually an aerial analyser which is very similar to a VSWR meter but does a lot more checking including coax loss, ground plane issues etc etc. Hope this helps

 

 

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AAAAH Thanks Micheal. That is just about word for word what Microair told me. The complaining pilot was quite close to me, whereas the guy that found the reception 5 x 5 was at the other end of the circuit several kilometers away. I have noticed it myself. Stations hundreds of miles away are as clear as a bell. Toorradin has the same frequency with Echuca and there are times when Echuca is clearer than Tooradin. Can be confusing if you don't hear the "Echuca Traffic" bit of the transmission......Another odd thing I have noticed is that when I am in certain areas the green "receive" light comes on permanently and all I can hear is a hiss that cannot be squelched out. I have a feeling that it may be a TV transmission tower, could that be correct?.....

 

 

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Guest Michael Coates

Hello again and you are absolutely correct in your assumptions. Firstly without pooh-poohing another manufacturer they do have issues with squelch sensitivity. Quite often when the radio gets warm/hot it is impossible to turn the squelch off. I believe they were fixing this at nominal charge for customers but you will need to check with them. We have seen several Microair radios which we have traded in doing exactly the same thing when they get warm/hot. It can also be that the radio is being overpowered by the TV transmission towers. I was flying in a sting aircraft to Tasmania that had a Microair radio, when I was flying past the Dandenong ranges (I think it was called) there were large TV towers upon the hill and the Microware heard nothing but static for about 5 min until I had transited through the zone. Quite convenient at the time because I was trying to set up skeds for crossing Bass Strait. I would suspect that the person complaining has an issue with the AGC of his radio. If you could never find out who it is please let him know and find out what radio he has and we may be able to offer a suggestion to fix. Hopefully, he does not have an XCOM radio because I would not like to see one of our radios with this problem! :eek:

 

 

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  • 2 weeks later...

Thanks MIchael, I have located him and will have a chat to him soon........................ I also have the "green light syndrome" around the Dandenongs, it's the TV transmission towers.... My radio is is fine now with no issues. I would recommend the noise filter (HM5 from radio spares) and the beads to everyone, I now have lovely clear reception.... Thanks again Michael

 

 

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