[OZAPRS] [aprssig] ICOM 706 Data Out (disc)

[Ray Wells]

Dick wrote:

>Just remember though. Portable operation and RF feedback go hand in hand.

>I think you should add something more than a resistor in the mic circuit

>to keep rf out.
>
>Cheers, Dick.
>VK7DIK
>
>Please Note.
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>On Fri, 20 Jul 2007 21:09:16 +1000, Andrew Rich <vk4tec at people.net.au>  
>wrote:
>
>  
>
>>I have another question
>>
>>I would like to use the radio for field events where we track horses.
>>
>>The icom outputs 8 volts DC from the MIC ,
>>
>>I have had a look, so most computer mic ports supply 2.5 volts for the
>>electret ?
>>
>>Maybe all that is required is a resistor ?
>>
>>
>>  -----Original Message-----
>>  From: aprssig-bounces at lists.tapr.org
>>[mailto:aprssig-bounces at lists.tapr.org]On Behalf Of Andrew Rich
>>  Sent: Friday, 20 July 2007 3:43 PM
>>  To: Aprssig
>>  Cc: ozaprs
>>  Subject: [aprssig] ICOM 706 Data Out (disc)
>>
>>
>>  Gudday
>>
>>  I see a port on the back of the ICOM 706 MKii G is marked for packet  
>>use.
>>
>>  It provides 1200 and 9600 baud connection points.
>>
>>  Would I be right in saying that the 9600 baud stage by passes the
audio
>>stage and is what they call a disc out ?
>>
>>  Cheers
>>
>>  Andrew VK4TEC
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>
>
>
>  
>
Remember that the electret insert and the gate of the FET it feeds is 
high impedance, making it more susceptable to small amounts of RF.

If you absolutely don't have to use the electret, from an RF feedback 
perspective, you would be better off with a low impedance (<600ohms) 
dynamic microphone.

Manufacturers of commercial SSB radios (Codan, etc) use a balanced input 
for the microphone, which aids in reducing any induced noises.

Ray vk2tv
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