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Re: 144 MHz TX inhibit on FT-847

>From: Estes Wayne-W10191 <W10191@motorola.com>
>This weekend I opened up my FT-847 to do a mod to mute microphone audio
when the radio is keyed from the data port.  As long as the radio was open,
I looked at the schematic and probed around the 144 MHz PA a little bit.
>J4003 is a connector on the VHF/UHF PA board with VHF control signals.
The pins that looked interesting are:
>Pin 1:  VHF T8
>Pin 5:  VHF AMP
>Pin 2:  VHF ALC

Your comments on the VHF/UHF board are interesting and I'll take a closer
look as I have the service manual.  But your initial reason for opening the
radio is strange.  The Yaesu manual states that when you use the DATA jack,
activating PTT disconnects the front mic?  Why did you fell a mod was
needed.  Did your FT-847 not operate correctly?

I have used this jack for psk-31 and for computer T/R keying when using a
computer generated cw.  The cw key is also controlled by the computer so
PTT isn't strictly needed since the radio operates semi break-in, but when
operating high power for eme I wan't to hard key the radio into xmit mode.
I also take Rx audio from this jack for the computer in psk-31 and for
running FFTDSP-42 sw thru the soundcard.

The VHF AMP line may just be a 2m band enable line.


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