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Icom A200 transceiver

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lapulce(at)sunrise.ch
Guest

Posted: Sat Nov 30, 2013 1:21 am Post subject: Icom A200 transceiver

[quote]

My name is Guido and I am new to this List. I have some trouble with my Icom A200 which is in my newly built Wittman Tailwind W10. Maybe this topic has already been discussed and if so can you tell where I can find this issue . 	  Quote: 	
		   	  Quote: 	
		   Here in Locarno Switzerland ( LSZL) my local airport the tower transmits with 2 antennas at the same frequency 134.825 ( one directly on the tower and the other about 7 miles north in the direction of the runway 26 ) They told me this is due to the mountains all around the airport. Only at a certain point flying between the two antennas ( for instance on long final ) I cannot hear the tower instructions and the tower hears me only when they shut down one antenna. There is absolutely no problem with all the other airtraffic on ground and in the air. All the other airplanes don't have this problem as we were told. I already changed the antenna, its position on the plane from the bottom to the top and the antenna cable with a double shielded one but with no result.Can anyone of the Forum give me some advice how to solve this problem. I contacted Icom America where I bought the transceiver but they too couldn't get me an answer.Thanks in advance and have a nice weekend.Guido





	






	


[b]

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m.j.gregory(at)talk21.com
Guest

Posted: Sun Dec 01, 2013 3:50 am Post subject: Icom A200 transceiver

Hello Guido,

 

It would be helpful for you to speak to the technicians who look after the ground radio systems at Locarno to find out whether there are 2 separate transmitters operating on 134.825, but at slightly different frequencies (known as offset carrier working). This can be adopted to avoid 2 identical signals interfering with each other – they are both within the pass band of the receiver and so should reinforce each other, but it is possible that they could generate a beat frequency that interferes with the signal-to-noise squelch circuit. 

 

I have no explanation to suggest why the ground receivers should be able to accept other people's transmissions and not those from your ICOM. However, the more you know about the technical setup on the ground that connects to the 2 separate antennas, the better placed you will be to discuss with ICOM what might be causing your problem.

 

Good luck!

 

Mike

Dr Mike Gregory

 

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Guido von Allmen

Sent: 30 November 2013 09:21

To: aeroelectric-list(at)matronics.com

Subject: Icom A200 transceiver

  	  Quote: 	
		  

My name is Guido and I am new to this List. I have some trouble with my Icom A200 which is in my newly built Wittman Tailwind W10. Maybe this topic has already been discussed and if so can you tell where I can find this issue . 

Here in Locarno Switzerland ( LSZL) my local airport the tower transmits with 2 antennas at the same frequency 134.825 ( one directly on the tower and the other about 7 miles north in the direction of the runway 26 ) They told me this is due to the mountains all around the airport. Only at a certain point flying between the two antennas ( for instance on long final ) I cannot hear the tower instructions and the tower hears me only when they shut down one antenna. There is absolutely no problem with all the other airtraffic on ground and in the air. All the other 

airplanes don't have this problem as we were told. I already changed the antenna, its position on the plane from the bottom to the top and the antenna cable with a double shielded one but with no result.

Can anyone of the Forum give me some advice how to solve this problem. 

I contacted Icom America where I bought the transceiver but they too couldn't get me an answer.

Thanks in advance and have a nice weekend.

Guido





	








[quote][b]

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Dec 01, 2013 8:19 am Post subject: Icom A200 transceiver

From: owner-aeroelectric-list-server(at)matronics.com 

[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of 

Guido von Allmen

Sent: 30 November 2013 09:21

To: aeroelectric-list(at)matronics.com

Subject: Icom A200 transceiver



My name is Guido and I am new to this List. I have some trouble with 

my Icom A200 which is in my newly built Wittman Tailwind W10. Maybe 

this topic has already been discussed and if so can you tell where I 

can find this issue .

Here in Locarno Switzerland ( LSZL) my local airport the tower 

transmits with 2 antennas at the same frequency 134.825 ( one 

directly on the tower and the other about 7 miles north in the 

direction of the runway 26 ) They told me this is due to the 

mountains all around the airport. Only at a certain point flying 

between the two antennas ( for instance on long final ) I cannot hear 

the tower instructions and the tower hears me only when they shut 

down one antenna. There is absolutely no problem with all the other 

airtraffic on ground and in the air. All the other

airplanes don't have this problem as we were told. I already changed 

the antenna, its position on the plane from the bottom to the top and 

the antenna cable with a double shielded one but with no result.

Can anyone of the Forum give me some advice how to solve this problem.

I contacted Icom America where I bought the transceiver but they too 

couldn't get me an answer.

Thanks in advance and have a nice weekend.

Guido

    I would not expect ICOM to be helpful . . . nor would

    it be helpful for you to 'do things' to your installation

    on the airplane.



    There are two ways that two antennas can work in close

    proximity on the same frequency to transmit . . .



    (1) you have two separate facilities, probably tied

    together by land line. In this instance, the operator

    of the ground based facilities chooses facility A

    or B to talk to any given airplane. This is done with

    a selector switch of some type . . . a switch that

    usually prevents simultaneous operation of both

    facilities.  This is, I suspect, what has been installed

    at your local airport. BOTH receivers can be active

    at all times but when one receiver gets a strong signal

    from an airplane, there's an indicator lamp that tells

    the operator which receiver took the call and he/she

    is expected to select the appropriate transmitter on

    which to reply, But in no case would you want the both

    transmitters to operate simultaneously.



    (2) two antennas are treated as an array for generating

    emissions from one source or two phase-locked sources.

    This is fraught with potential for compromised transmissions

    as the receiving station (airplane) moves through the

    standing waves set up by troughs and peaks of alternately

    opposing and aiding signals from the two antennas . . .

    heard in the airplane as 'flutter' on the received

    signal.



    If you are experiencing a null zone between the two

    antennas but do not hear flutter or a beat note

    between the two transmitted signals . . . then it's

    probable that system (1) is installed and you have

    a severe sensitivity issue with your installation.



    I suspect an open coax.



    Check SWR on your airplane's comm antenna from

    the transceiver end of the feedline. How's your

    radio's performance for communicating with other

    facilities that do not have remotely located

    transceivers on a shared frequency? From 1000

    feet up, you should be able to talk with a

    ground station that is 25 miles away (assuming

    no intervening mountains) or other airplanes

    from 50 to 100 miles away.





   Bob . . .

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