Is my AFSK A problem a Ghost?

[dougfree]

I am trying to determine if I am trying to track down a problem that  
doesn't have an answer.  I have a on and off problem, with AFSK A and  
RTTY.  I key and send tones, see bars on ALC but get no RF and do not  
hear anything on Monitor playback.

Everything works OK in Data A both RTTY and PSK.  Same software same  
signals out.  Maybe 1 out of 20 times something happens and AFSK A  
works and contacts are made!  I know Data A will work but the software  
doesn't handle 2125 offset when you reverse Data A to get LSB.  Makes  
things awkward to tune correctly and you do not get to use Dual BP  
which is a big plus!

I have tried various power, level, and input settings, and just about  
anything else I can think of so if someone has any advice to offer I  
would appreciate it.  Or...  maybe it is on the list to be addressed?

73s,
Doug - W5ION



_________________
Doug Freeman
[hidden email]
www.dougfree.com



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[Greg - AB7R]

Doug.

You have your tones set on the K3 Pitch to something different than  
your digital mode software is set to.  If you set them to the same  
(usually 2125 with 170Hz shift) you will be all set.

73
Greg
AB7R

On Apr 30, 2009, at 11:19 AM, Doug Freeman wrote:

> I am trying to determine if I am trying to track down a problem that
> doesn't have an answer.  I have a on and off problem, with AFSK A and
> RTTY.  I key and send tones, see bars on ALC but get no RF and do not
> hear anything on Monitor playback.
>
> Everything works OK in Data A both RTTY and PSK.  Same software same
> signals out.  Maybe 1 out of 20 times something happens and AFSK A
> works and contacts are made!  I know Data A will work but the software
> doesn't handle 2125 offset when you reverse Data A to get LSB.  Makes
> things awkward to tune correctly and you do not get to use Dual BP
> which is a big plus!
>
> I have tried various power, level, and input settings, and just about
> anything else I can think of so if someone has any advice to offer I
> would appreciate it.  Or...  maybe it is on the list to be addressed?
>
> 73s,
> Doug - W5ION
>
>
>
> _________________
> Doug Freeman
> [hidden email]
> www.dougfree.com
>
>
>
> ______________________________________________________________
> Elecraft mailing list
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... [show rest of quote]

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[Ron NA9F]

Doug I use DM-780 and discovered the same thing you are experiencing once in a while. I finally figured out what I was doing wrong.  I narrowed down my K3 filter to 250 hz and saw on the display that I was centered on 1500 hz in Data A mode but when I switched to AFSK for RTTY it was centered on 1000 hz. If If I click on a waterfall very far from the 1000 hz I will not hear or tx the tones. Try finding your center BW tone/freq on the waterfall and tune the station to that and see if your monitor and tx output works.

Ron NA9F



no RF and do not  
hear anything on Monitor playback.

Everything works OK in Data A both RTTY and PSK.  

73s,
Doug - W5ION



_________________
Doug Freeman
[e-mail]
www.dougfree.com



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[Richard Ferch]

Doug,

DM-780 appears to start with its tuning guides at 1415/1585, which does not
match any of the K3's RTTY pitch settings exactly, but is quite close to the
K3's 1445 Hz setting. With the K3 in AFSK A sub-mode, hold the K3's PITCH
button (just above the VFO B knob) to see the pitch displayed in the main
display. Using the VFO A knob, you can adjust the K3's Pitch setting to
2125, 1445, 1275 or 915 Hz. I would suggest that for DM-780, you start by
setting the K3's pitch in AFSK A to 1445. This will work fine at wider
filter settings. If you are using a very narrow filter setting on the K3,
you may have to move DM-780's tuning guides slightly to center them on 1530
Hz instead of 1500 Hz.

I would also suggest disabling AFC in DM-780, as that can cause the tuning
guides to move away from the center of the filter bandpass. If you use the
K3's tuning knob to do all of your tuning, you will always be centered in
the bandpass. If the radio's tuning seems too touchy for this, try pressing
the K3's FINE button to see if that helps.

I don't usually use DM-780 (DM-780 and HRD each seem to work on their own,
but the combination locks up on my computer), so I am not very familiar with
it. However, it looks to me as if DM-780 expects the radio to be on upper
sideband, whereas the K3's AFSK A uses lower sideband. You may have to press
the Reverse button in DM-780 to get it to decode RTTY correctly in AFSK A
sub-mode.

DATA A works fine for you because it is centered on 1500 Hz (the same as
DM-780), and it uses upper sideband (ditto). On the other hand, in DATA A
mode you do not have access to the K3's RTTY-specific features (the Dual PB
filter, spot tones and CWT tuning aids, and text decode).

Note also that with DM-780 you must use AFSK A and not FSK D sub-mode for
RTTY. AFAIK, DM-780 does not support FSK keying, only AFSK.

73,
Rich VE3KI


> no RF and do not  
> hear anything on Monitor playback.
>
> Everything works OK in Data A both RTTY and PSK.  
>
> 73s,
> Doug - W5ION


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[Richard Ferch]

In my previous message I forgot to mention one other difference between AFSK
A and DATA A sub-modes. In AFSK A, the K3's dial displays the actual mark
frequency, whereas in DATA A the dial displays the suppressed carrier
frequency.

Thus, to tune in the W1AW RTTY bulletins on 14095 kHz, in AFSK A you would
simply set the K3's tuning dial to 14095. In DATA A, if you wanted to center
the signal on exactly 1500 Hz, you would set the radio's dial to 14093.415
kHz (1585 Hz below the desired mark frequency). I don't know for sure what
frequency DM-780/HRD would log in each of these two cases, nor how to
correct any offset if there is one.

73,
Rich VE3KI

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