[Elecraft] K3s on rtty

[efortner]

Rich,
Thanks for the explanation. I sure thought I could get FSK keying with the
LP-Bridge but I understand what you are saying. I was using USB SignaLink
with a modification to a FSKit circuit published in QST a few years back for
FSK keying of my Icom Pro III and it worked well. I have used AFSK before
but
Still prefer FSK so I guess it's back to getting it all set up again.
73, Earl, K4KAY


-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of
Richard Ferch
Sent: Wednesday, October 21, 2015 2:59 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3s on rtty

You cannot use the same serial port for CAT (rig) control and FSK keying.
The reason has nothing to do with COM port sharing between parallel rig
control applications, which is the issue LP-Bridge solves. 
The fundamental issue is that FSK keying and CAT control use the RS-232
signal lines in incompatible ways. You must use a different serial port for
FSK keying than the one you use for CAT control, and no port-sharing method
(LP-Bridge, com0com, VSPE) can change this. LP-Bridge will allow you to use
two rig control programs in parallel, but it will not allow you to use one
serial port in two fundamentally incompatible ways.

For FSK keying you need a one-transistor switching interface between the
RS-232 voltage levels (plus and minus 12V) on the COM port you are using for
FSK and the FSK keying input (pin 1) on the K3's ACC connector.

If you don't already have an FSK keying circuit, it would be easier to use
AFSK with MMTTY. From the operator's point of view, AFSK A on the K3 is
almost indistinguishable from FSK D. The K3's transmitted signals using AFSK
are just as clean as its FSK. In fact, until relatively recently the K3's
AFSK was cleaner than its FSK. And with AFSK, no special keying circuit is
necessary. Indeed, if you are using the K3S's USB port for rig control, I
believe no new cables are needed at all. 
Just tell MMTTY to use the sound card inside the K3S.

If you were using a SignaLink before, that was AFSK. You do not need the
SignaLink with the K3S, because everything it does is already provided for
inside the K3S, but apart from changing the sound card MMTTY uses, there
should be little difference between using the SignaLink and using the K3S's
internal sound card.

73,
Rich VE3KI


K4KAY wrote:

> From Earl, K4KAY. I now have lp-bridge running and cat control is working
> fine. I have to give credit to my friend Richard, K4KRW for his help.
>
>
>
> I am now trying to get MMTTY going and reading other posts about using
> transistor to invert the signal etc, to do FSK. I have done this with
>
> Other rigs but also remember others saying I no longer need the signal
link.
> Which rtty program would be simpler. I already have MMTTY on
>
> My computer and not successful on my first try. I assume I would use the
> lp-bridge to get it on the K3s but when I assign the comport on the
>
> Lp-bridge MMTTY tells me I have no comport.
>
>
>
> I am open for suggestions. I prefer MMTTY but can go another route if
> simpler and I want to stay with FSK with my K3s and P3 panadapter with the
> VGS option.
>
>
>
> Regards,
>
> Earl, K4KAY
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