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RTTY via FSK-D

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Brett Howard

RTTY via FSK-D

So I'm thinking about wiring up the FSK IN pin on the AUX connector to
do RTTY TX "properly". I'm curious of a few things before I take the
time to make the cable.

First off how do people usually drive this signal? I assume its usually
taken off of a serial port... I've tried a few RTTY apps and I've
gotten them all to work via AFSK and all seem to have their pros/cons.
I have a feeling in the end that I'll probably most use MMTTY being that
it has a very nice interface into N1MM (unless there is another
application that has a nice interface into N1MM that I should be aware
of).

Finally my last question is that if this comes off of a UART how has the
timing been for people? I remember a while back I used a UART to to CW
keying in N1MM. I remember being embarrassed by the CW that was sent
and I've since bought a K1EL WKUSB kit and put that together... Very
happy with that little box. Would I have these same timing issues in
this FSK_IN setup? If there was ever a stupid thing is trying to use
Windows as an RTOS. ;)

Anyway thoughts appreciated.

~Brett (KC7OTG)

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Dave Hachadorian

Re: RTTY via FSK-D

Comments interspersed.

Dave Hachadorian, K6LL
Yuma, AZ

--------------------------------------------------
From: "Brett Howard" <[hidden email]>
Sent: Thursday, March 04, 2010 1:11 AM
To: <[hidden email]>
Subject: [Elecraft] RTTY via FSK-D

> So I'm thinking about wiring up the FSK IN pin on the AUX
> connector to
> do RTTY TX "properly". I'm curious of a few things before I
> take the
> time to make the cable.
>
> First off how do people usually drive this signal? I assume
> its usually
> taken off of a serial port...

Yes, circuit is shown here:
http://www.aa5au.com/rttyinterface.html

I've tried a few RTTY apps and I've
> gotten them all to work via AFSK and all seem to have their
> pros/cons.
> I have a feeling in the end that I'll probably most use MMTTY
> being that
> it has a very nice interface into N1MM (unless there is another
> application that has a nice interface into N1MM that I should
> be aware
> of).

MMTTY is the way to go.

>
> Finally my last question is that if this comes off of a UART
> how has the
> timing been for people?

The timing is solid.

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alsopb

Re: RTTY via FSK-D

Comment on the FSK circuit.
MMTTY used to send upside down in FSK and there was no way to change it
via software.
It is possible the circuit may have to be modified to invert the polarity.

73 de Brian/K3KO

Dave Hachadorian wrote:

> Comments interspersed.
>
> Dave Hachadorian, K6LL
> Yuma, AZ
>
> --------------------------------------------------
> From: "Brett Howard" <[hidden email]>
> Sent: Thursday, March 04, 2010 1:11 AM
> To: <[hidden email]>
> Subject: [Elecraft] RTTY via FSK-D
>
>> So I'm thinking about wiring up the FSK IN pin on the AUX
>> connector to
>> do RTTY TX "properly". I'm curious of a few things before I
>> take the
>> time to make the cable.
>>
>> First off how do people usually drive this signal? I assume
>> its usually
>> taken off of a serial port...
>
>
> Yes, circuit is shown here:
> http://www.aa5au.com/rttyinterface.html
>
>
>
>
> I've tried a few RTTY apps and I've
>> gotten them all to work via AFSK and all seem to have their
>> pros/cons.
>> I have a feeling in the end that I'll probably most use MMTTY
>> being that
>> it has a very nice interface into N1MM (unless there is another
>> application that has a nice interface into N1MM that I should
>> be aware
>> of).
>
>
> MMTTY is the way to go.
>
>
>> Finally my last question is that if this comes off of a UART
>> how has the
>> timing been for people?
>
>
> The timing is solid.
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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> Please help support this email list: http://www.qsl.net/donate.html
>
>
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.733 / Virus Database: 271.1.1/2721 - Release Date: 03/03/10 19:34:00
>

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Richard Ferch

Re: RTTY via FSK-D

In reply to this post by Brett Howard

Brett,

Regarding the timing problems you had with CW from a serial port: In
this situation the timing is not done by the UART, it is done directly
by the CPU toggling the control line (usually DTR) on and off, and is
therefore subject to non-RTOS timing problems. If you are using a UART
to do FSK on its standard TxD data output, the timing is controlled by
the clock in the UART, so the timing issues that affect serial port CW
do not affect FSK done in this way. In a sense, the UART for FSK is a
logical equivalent to the Winkeyer chip for CW.

However, this only applies if the UART is capable of doing 5-bit codes
at 45.45 baud. The UARTs used in PC serial ports have this capability,
but most USB-to-serial adapters do not. One giveaway is the maximum
speed supported by the adapter; if it is greater than 230 kb/sec, then
the minimum speed is too high for RTTY. Currently available single
USB-to-serial adapters are too fast for RTTY, but some 4-port or 8-port
USB adapters can handle the slower speed.

There is an add-in for MMTTY called EXTFSK that is capable of doing
45.45 baud RTTY with any USB-to-serial adapter. EXTFSK can key any of
the TxD, DTR or RTS signal lines on any serial port or serial adapter;
in fact, it can even do FSK keying via a parallel port. The downside is
that the timing is handled by the CPU, not by the UART. However,
apparently EXTFSK uses the same sound card timer that is used for AFSK,
so the timing of EXTFSK-sent FSK should be the same as the timing of
sound card AFSK, no better and no worse.

You do need a keying circuit between the serial port and the K3's FSK
input. The same kind of one-transistor or opto-isolator circuit that is
usually used for serial port CW or PTT will also work for FSK keying.

73,
Rich VE3KI

KC7OTG wrote:

> So I'm thinking about wiring up the FSK IN pin on the AUX connector to
> do RTTY TX "properly". I'm curious of a few things before I take the
> time to make the cable.
>
> First off how do people usually drive this signal? I assume its usually
> taken off of a serial port... I've tried a few RTTY apps and I've
> gotten them all to work via AFSK and all seem to have their pros/cons.
> I have a feeling in the end that I'll probably most use MMTTY being that
> it has a very nice interface into N1MM (unless there is another
> application that has a nice interface into N1MM that I should be aware
> of).
>
> Finally my last question is that if this comes off of a UART how has the
> timing been for people? I remember a while back I used a UART to to CW
> keying in N1MM. I remember being embarrassed by the CW that was sent
> and I've since bought a K1EL WKUSB kit and put that together... Very
> happy with that little box. Would I have these same timing issues in
> this FSK_IN setup? If there was ever a stupid thing is trying to use
> Windows as an RTOS. ;)

Dave Hachadorian

Re: RTTY via FSK-D

In reply to this post by alsopb

--------------------------------------------------
From: "Brian Alsop" <[hidden email]>
Sent: Thursday, March 04, 2010 8:11 AM
To: "Dave Hachadorian" <[hidden email]>
Cc: "Brett Howard" <[hidden email]>; "Elecraft
Reflector" <[hidden email]>
Subject: Re: [Elecraft] RTTY via FSK-D

> Comment on the FSK circuit.
> MMTTY used to send upside down in FSK and there was no way to
> change it via software.
> It is possible the circuit may have to be modified to invert
> the polarity.
-------------------------------------------------

I am using the simple npn transistor circuit. Keying polarity can
be selected in the K3.
My setting is K3/config/fsk pol = 1

Dave Hachadorian, K6LL
Yuma, AZ

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Joe Subich, W4TV-4

Re: RTTY via FSK-D

In reply to this post by alsopb

> MMTTY used to send upside down in FSK and there was no way to
> change it via software.

MMTTY does not "send upside down." It generates a "1" (high) on
the output of the UART for mark which is correct. Most interfaces
use a simple NPN transistor which turns that "1" into a closed
contact (again correct for the old 60 mA "loop" circuits).

Unfortunately, many rigs expect the FSK input to be OPEN (or
high due to their internal pull-up) for Mark. The user needs
to read his transceiver manual and if it is normally "mark open"
or "mark High", select "REV" in the menu ... this applies to
such a diverse group of transceivers as the FT-1000D, FT-1000MP,
IC-706mkIIg, TS-870, etc.

Again, MMTTY is not "upside down" ... it is the interface
standards that are still rooted in the 60 mA current loop
instead of the data communications world where Mark=1/Space=0.

73,

... Joe, W4TV

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Brian Alsop
> Sent: Thursday, March 04, 2010 10:12 AM
> To: Dave Hachadorian
> Cc: Elecraft Reflector
> Subject: Re: [Elecraft] RTTY via FSK-D
>
>
> Comment on the FSK circuit.
> MMTTY used to send upside down in FSK and there was no way to
> change it
> via software.
> It is possible the circuit may have to be modified to invert
> the polarity.
>
> 73 de Brian/K3KO
>
> Dave Hachadorian wrote:
> > Comments interspersed.
> >
> > Dave Hachadorian, K6LL
> > Yuma, AZ
> >
> > --------------------------------------------------
> > From: "Brett Howard" <[hidden email]>
> > Sent: Thursday, March 04, 2010 1:11 AM
> > To: <[hidden email]>
> > Subject: [Elecraft] RTTY via FSK-D
> >
> >> So I'm thinking about wiring up the FSK IN pin on the AUX
> >> connector to
> >> do RTTY TX "properly". I'm curious of a few things before I
> >> take the
> >> time to make the cable.
> >>
> >> First off how do people usually drive this signal? I assume
> >> its usually
> >> taken off of a serial port...
> >
> >
> > Yes, circuit is shown here: http://www.aa5au.com/rttyinterface.html
> >
> >
> >
> >
> > I've tried a few RTTY apps and I've
> >> gotten them all to work via AFSK and all seem to have their
> >> pros/cons.
> >> I have a feeling in the end that I'll probably most use MMTTY
> >> being that
> >> it has a very nice interface into N1MM (unless there is another
> >> application that has a nice interface into N1MM that I should
> >> be aware
> >> of).
> >
> >
> > MMTTY is the way to go.
> >
> >
> >> Finally my last question is that if this comes off of a UART
> >> how has the
> >> timing been for people?
> >
> >
> > The timing is solid.
> >
> >
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> >
> >
> >
> ----------------------------------------------------------------------
> > --
> >
> >
> > No virus found in this incoming message.
> > Checked by AVG - www.avg.com
> > Version: 9.0.733 / Virus Database: 271.1.1/2721 - Release
> Date: 03/03/10 19:34:00
> >
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Hank Garretson

Re: RTTY via FSK-D

I've never had occasion to use it and maybe I misunderstand what it is
supposed to do, but it looks as if one can switch MMTTY transmit logic as
follows:

Open MMTTY

Option

Setup MMTTY

TX

Check or uncheck Invert Logic

73,

Hank, W6SX

Mammoth Lakes, California

Elevation 8083 feet in John Muir's Range of Light
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Richard Ferch

Re: RTTY via FSK-D

In reply to this post by Brett Howard

The "Invert logic" option in MMTTY only applies to PTT. The UART's FSK
output cannot be inverted. If you are using EXTFSK, there is an option
to invert the FSK logic in EXTFSK. This is immaterial with a K3, though;
all you have to do is adjust CONFIG:FSK POL (set it = 1 for normal
polarity).

73,
Rich VE3KI

W6SX wrote:

> I've never had occasion to use it and maybe I misunderstand what it is
> supposed to do, but it looks as if one can switch MMTTY transmit logic as
> follows:
>
> Open MMTTY
>
> Option
>
> Setup MMTTY
>
> TX
>
> Check or uncheck Invert Logic

Ed Muns, W0YK

Re: RTTY via FSK-D

In reply to this post by Brett Howard

> First off how do people usually drive this signal? I assume
> its usually taken off of a serial port... I've tried a few
> RTTY apps and I've gotten them all to work via AFSK and all
> seem to have their pros/cons.

The most common way, and compatible with most loggers and RTTY software, is
to drive the K3 FSK and PTT lines on the AUX connecter from a serial COM
port on the PC. All that's needed is a level shifter from the PC RS-232 to
the K3 TTL. Use a 1-2Kohm base resistor and an NPN switching transistor in
the FSK and PTT lines. A diagram of this (except for the K3 AUX connector
pins which is in the K3 manual) can be found many places, including
www.rttycontesting.com.

> I have a feeling in the end that I'll probably most use MMTTY
> being that it has a very nice interface into N1MM (unless
> there is another application that has a nice interface into
> N1MM that I should be aware of).

In the recent RTTY Contesting Survey just completed, 75% of the respondents
use MMTTY. Look no further. It is beautifully integrated with N1MM Logger.

> Finally my last question is that if this comes off of a UART
> how has the timing been for people? I remember a while back
> I used a UART to to CW keying in N1MM. I remember being
> embarrassed by the CW that was sent and I've since bought a
> K1EL WKUSB kit and put that together... Very happy with that
> little box. Would I have these same timing issues in this
> FSK_IN setup? If there was ever a stupid thing is trying to
> use Windows as an RTOS. ;)

Timing is perfect. I've never heard of a problem, especially because of the
UART in the PC.

Ed - W0YK
-----------------------------------------------
Ed Muns
Muns Vineyard - www.munsvineyard.com
FaceBook - www.facebook.com/munsvineyard

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Roy Davis

Re: RTTY via FSK-D

In reply to this post by Richard Ferch

Is the duty cycle of the K3 so that it will handle 100 watts output safely
in a cw or rtty contest?

At home I use a amplifier with 40 watts of drive. But, I would like to be
able to operate portable at the river with just the K3 in a cw or rtty
contest if it can handle the continious duty on these modes.

Roy - WK4Y

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John_N1JM

Re: RTTY via FSK-D

I don't know about most of you but with WL and MMTTY with the simple transistor keyer, I have to set FSK-pol to 0 in my K3.

Dave Hachadorian

Re: RTTY via FSK-D

In reply to this post by Roy Davis

> Is the duty cycle of the K3 so that it will handle 100 watts
> output safely
> in a cw or rtty contest?
>
> At home I use a amplifier with 40 watts of drive. But, I would
> like to be
> able to operate portable at the river with just the K3 in a cw
> or rtty
> contest if it can handle the continious duty on these modes.

I have run both of mine flat-out at 100 watts in the NAQP RTTY
contest, where amps are not allowed. There were no problems. The
fan comes on at high speed, but PA temp stabilizes way below the
high temp cutoff point.

Dave Hachadorian, K6LL
Big Bear Lake, CA

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