[1000mp] PTT keying current on FT1000MKV Field

[Jim W7RY]

Yes. You are missing something.

Take a look at the schematic. There is a diode in between the RCA PTT jack 
and the packet/RTTY jacks. This diode gives an extra .6 volt drop on the 
PTT line on the packet and RTTY jacks. You need a very "hard" (relay) low 
to get the radio to transmit. I just moved my RTTY PTT to the RCA connector 
and the problem is solved.

In my opinion, very poor design philosophy.

They should have added another inverter so a transistor or opto isolator 
could key the radio.


Hope this helps!

73
Jim W7RY


At 11:31 AM 12/27/2004, Mark wrote:
>In building a FSK interface for my FT1000MKV Field. I was having trouble 
>with the PTT, the
>FSK part worked fine.  What I found was that the PTT keying circuit of the 
>FT1000 needed
>a current sink of about 18ma which my poor little opto-isolator was not up 
>to.  This was in
>conflict with the ops manual which indicates a current sink requirement of 
>1.5ma.
>
>(The FSK needed less than .5 ma sink.)
>
>Am I missing something?
>
>Mark N2QT
>
>
>
>
>
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