K3 - AFSK A

[Stewart Baker]

I have been busy setting up MMVARI together with N1MM to use in
RTTY contests. I have not encountered any real problems, however I
am a little confused when it comes to using the K3 in the AFSK A
mode.

I am using this mode because it always has the RTTY LSB selected
as default. The audio tones are fed into the K3 via the LINE IN.

In the Data Mode section of the K3 Owners Manual it says:-
AFSK A also uses Audio-shift transmit, but is optimized for RTTY.

The VFO displays the RTTY Mark frequency, and LSB is "normal".

I am not seeing the Mark frequency displayed on the VFO, but one
which seems to represent the suppressed carrier. The displayed
frequency is offset from the Mark frequency by about 1.3 kHz.
This would correspond with the middle of the K3 filter passband.

It would be nice to display the real (yes I know it's audio) Mark
frequency as this seems to be a standard.

a) Am I missing something in my K3 setup ?
or
b) The manual is wrong ?
or
c) Something else ?

73
Stewart G3RXQ
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[KK7P]

Hello Stewart!

Be sure you use the PITCH control to select the tone pair you desire to
use. The K3 will then display the RF frequency corresponding to the RTTY
Mark tone.  As you change pitches, the frequency display won't alter but
the offset of the radios suppressed carrier will move in accordance with
the selected PITCH.

If you engage the dual tone RTTY filter, it will be set up for the
selected PITCH.

Be sure the RTTY program is set to the same pitch.  Some programmes are
waterfall-based and change the Tx tones to match the Rx tones.  If you
are using such a program, you may be better off with DATA A, and if you
want LSB then hold ALT to change sidebands for DATA A so that you see
the LSB icon. IN thie case of using DATA A, the radio will display the
suppressed carrier frequency rather than the MARK frequency.

73,

Lyle KK7P
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[Joe Subich, W4TV-4]

> I am not seeing the Mark frequency displayed on the VFO, but one
> which seems to represent the suppressed carrier. The displayed
> frequency is offset from the Mark frequency by about 1.3 kHz.
> This would correspond with the middle of the K3 filter passband.

What do you have set for "pitch" in AFSK A?  If your mark is 2125
but the AFSK A "Pitch" is 915, you would see an approximately 1300
Hz offset.

73,

   ... Joe, W4TV
 

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Stewart Baker
> Sent: Monday, February 09, 2009 10:02 AM
> To: Elecraft Reflector
> Subject: [Elecraft] K3 - AFSK A
>
>
> I have been busy setting up MMVARI together with N1MM to use in
> RTTY contests. I have not encountered any real problems, however I
> am a little confused when it comes to using the K3 in the AFSK A
> mode.
>
> I am using this mode because it always has the RTTY LSB selected
> as default. The audio tones are fed into the K3 via the LINE IN.
>
> In the Data Mode section of the K3 Owners Manual it says:-
> AFSK A also uses Audio-shift transmit, but is optimized for RTTY.
>
> The VFO displays the RTTY Mark frequency, and LSB is "normal".
>
> I am not seeing the Mark frequency displayed on the VFO, but one
> which seems to represent the suppressed carrier. The displayed
> frequency is offset from the Mark frequency by about 1.3 kHz.
> This would correspond with the middle of the K3 filter passband.
>
> It would be nice to display the real (yes I know it's audio) Mark
> frequency as this seems to be a standard.
>
> a) Am I missing something in my K3 setup ?
> or
> b) The manual is wrong ?
> or
> c) Something else ?
>
> 73
> Stewart G3RXQ
> ______________________________________________________________
> 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

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[Stewart Baker]

Hi Lyle,
Thanks for your reply. A bit more investigation shows that
switching between AFSK A, DATA A, USB or LSB makes no difference
as far as the frequency offset is concerned.

What does make a difference is switching between Digital mode and
CW/SSB in N1MM...
In non Digital Modes the K3 VFO frequency display corresponds
exactly with the Bandmap for any K3 mode selected.

However, it appears that in the Digital modes N1MM offsets the K3
carrier frequency whilst showing the correct Mark frequency on the  
Bandmap and MMVARI cursor.

Or, I think that is what is happening... My brain hurts !

73
Stewart G3RXQ
On Mon, 09 Feb 2009 07:11:25 -0800, Lyle Johnson wrote:
> Hello Stewart!
>
> Be sure you use the PITCH control to select the tone pair you
desire to
> use. The K3 will then display the RF frequency corresponding to
the RTTY
> Mark tone.  As you change pitches, the frequency display won't
alter but
> the offset of the radios suppressed carrier will move in
accordance with
> the selected PITCH.
>
> If you engage the dual tone RTTY filter, it will be set up for
the
> selected PITCH.
>
> Be sure the RTTY program is set to the same pitch.  Some
programmes are
> waterfall-based and change the Tx tones to match the Rx tones.
 If you
> are using such a program, you may be better off with DATA A, and
if you
> want LSB then hold ALT to change sidebands for DATA A so that
you see
> the LSB icon. IN thie case of using DATA A, the radio will
display the
> suppressed carrier frequency rather than the MARK frequency.
>
> 73,
>
> Lyle KK7P


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