[Elecraft] K3 - MMTTY interface for FSK

[Joe Subich, W4TV]

> All along I have been using COM 1 on my PC for FSK keying. I have
> been using pin 3 to Pin 1 on the Acc K3 socket. I have not used Pin
> 7 (PTT) to Pin 4 on the K3.

I trust you have been using an NPN transistor between the RS-232 output
(+/- 9V) of the serial port and the TTL input (0 to +5V) of the K3 ACC
port.

If you are not using Radio Command and have not connected Pin 7 of the
serial port to pin 4 of the K3 (again using an NPN transistor), I do
not know how the K3 would ever switch to transmit.

73,

    ... Joe, W4TV


On 7/14/2016 10:45 AM, N2TK, Tony wrote:
> I am having brain freeze. I must have changed something but not sure what.
> Both K3's had been working fine on FSK using MMTTY for years. I can still
> receive fine, but I can't transmit on either.
>
> I am using LP Bridge which is talking fine to either K3.
>
> When I hit Xmit in MMTTY the program shows it is sending, but it does not
> key the K3.
>
>
>
> All along I have been using COM 1 on my PC for FSK keying. I have been using
> pin 3 to Pin 1 on the Acc K3 socket. I have not used Pin 7 (PTT) to Pin 4 on
> the K3.
>
> When I measure voltage on Com 1 pin 3 it is -9V. When I hit Xmit in MMTTY it
> stays at -9V.
>
>
>
> MMTTY is setup as follows:
>
> -          Misc tab - COM-TxD (FSK)
>
> -          TX tab - Port Com1.
>
> -          I am not using Radio Command
>
>
>
> K3
>
> -          PTT-KEY is OFF-OFF.
>
> One K3 has KIO3A using RS232. The other has KIO3B using USB.
>
>
>
> Also if I ground pin 4 on the Acc socket it does not transmit.
>
> Tried another Com port and made the change in MMTTY but the same result.
>
> What could I have inadvertently changed so that the Com 1 Pin 3 to stay at
> -9V?
>
>
>
> Tnx for any feedback.
>
> N2TK, Tony
>
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