[Elecraft] Icom SM-8 U/D buttons?

[Don Wilhelm]

Martin,

According to the SM-8 microphone schematic, the UP button connects the 
UP/DN line directly to ground, but the DN button connects the UP/DN 
button to ground through a 470 ohm resistor.  You would have to convert 
these closures to 2 lines each of which is a circuit direct to ground, 
so you would have to provide some sort of level sensing at the input of 
whatever adapter circuit you would come up with.

Much microphone information can be found on G4WPW's wonderful collection 
of microphone connections/diagrams/etc.  Look at 
http://www.timroberts-vk4yeh.id.au/G4WPW_mic_connections/index.htm#icom

73,
Don W3FPR

DM4iM wrote:
> List,
> According to the Icom SM-8 Desktop Microphone manual, there is only 1
> wire for the Up and Down buttons.
> So i suspect Icom feeds a positive voltage for up and a negative voltage
> for down (or vice versa).
> How to adapt this to make it work with K3?
> I had good audio reports so far.
>
> Martin
>
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