I'm using DATA A mode. Contrary to the manual, the Dual Tone RTTY filter
will not activate in DATA A mode. When attempted, the display shows N/A.
To use the DTF, I changed to AFSK A mode. This allows the DTF to work
however the center frequency of the IF changes from 1500Hz to 1356Hz. I will
notify Elecraft about these.
As far as copying RTTY with the 200hz filter and DTF....It appears to work
fine. The only difference I could detect on the waterfall with DTF turned on
is the obvious "hole" between the filter peaks.
Steve Ellington
[EMAIL PROTECTED]
----- Original Message -----
From: "K3KO" <[EMAIL PROTECTED]>
To: <elecraft@mailman.qth.net>
Sent: Sunday, May 18, 2008 10:12 AM
Subject: Re: [Elecraft] RTTY filter for K3
Please turn on the K3 dual peak RTTY filter and tell us what you see then.
Brian/K3KO
n4lq wrote:
Axel
I was the first to respond to your question. I told you that I was
listening
to RTTY through the 200 Hz, 5 pole filter and it worked fine. Then the
experts came on here and using many words, explained why it couldn't work
because it is too narrow. Maybe they do not actually have the filter but
I
do.
Looking at the waterfall on MixW, 200Hz filter engaged, a RTTY signal
easily
fits within the waterfall's passband with a little room on either side.
The
vertical stripes of the RTTY signal do not quiet reach the outer edge of
the
waterfall which tells me that the "data" is not being chopped off. Both
weak
and strong RTTY signals seem perfectly copyable.
No I would not use this in a contest unless I had a bandscope so I could
find signals. I have ordered the LP-PAN which should take care of that
little detail.
73
Steve Ellington
[EMAIL PROTECTED]
----- Original Message -----
From: "Axel Kaiser" <[EMAIL PROTECTED]>
To: "Elecraft Reflector" <elecraft@mailman.qth.net>
Sent: Sunday, May 18, 2008 4:14 AM
Subject: [Elecraft] RTTY filter for K3
To all you filter aficionados,
first of all thank you very much for all your detailed answers to my
original question, which roofing filter ist best for RTTY operation of
the
K3. Lots of very detailed and informative answers were given and even a
general discussion on this issue among several others was started. But to
tell you the truth, I am still somewhat uncertain, which filter to order
with my K3.
One of my theory books about HF technology, modulation, bandwidth and so
forth, tells me, that the necessary bandwidth for a 170 Hz shift RTTY
signal
should be around 320 Hz. Now some of you guys write, that you are using a
250 Hz filter for RTTY operation. A 250 Hz filter though has this 250 Hz
(ok, a few Hz more in reality) bandwidth at - 6dB attenuation, which
means
that the actual bandwidth at about 0 db is even less.
So my understanding for a 170 Hz shift RTTY operation is, to use a filter
of
at least 400 - 500 Hz (at -6dB) in order to get all the information
through
the filter. This I can confirm also with my current OMNI VI+ which does
not
allow me to copy RTTY signals with a 250 Hz filter . So please, where is
the
point which I am missing with the K3, that you can work weak RTTY signals
with a 250 Hz roofing filter??
Best 73 de
Axel, DL3ZH
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