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RTTY Problems

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Ken Alexander-2

RTTY Problems

Hi folks,

I'm operating in the BARTG RTTY contest this weekend
with my K2 with a Tigertronics SL-1+ audio interface
and a MicroHam CW Keyer, which handles the computer
control of the K2. I'm using MMTTY and N1MM logger.

Everything worked fine last night. I was in RTTY mode
because the DSP filters are set up nicely for RTTY.
(The crystal filters in RTTY mode are unusable for
RTTY because they're centred on voice audio
frequencies and not RTTY freqs. But that's another
story.)

Anyway, the real problem started when I started
operating this morning. I called someone and the
interface keyed the PTT line but no transmitter
output. I hit the K2's Tune button and get full
output. I switch to LSB and transmit and get full
output on RTTY, but of course the filter situation is
even worse for RTTY operation when in LSB.

Strange that it would work OK all evening and then not
the next morning. I guess that's my punishment for
sleeping during a contest!

Any theories, suggestions or recommendations would be
most welcome!

73 and thanks,

Ken Alexander, VE3HLS

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list1

Re: RTTY Problems

> (The crystal filters in RTTY mode are unusable for
> RTTY because they're centred on voice audio
> frequencies and not RTTY freqs. But that's another
> story.)
Hi Ken,
As far as the other story goes....center them on 2210 Hz or whatever the
RTTY center frequency is, then narrow them down to about 400 hz wide and
then it will work fabulously. My PK232 is centered on 2210 Hz so I aligned
the K2 filters to match. Now I can do PACTOR I with my K2.
See:
http://www.pituch.net/p/Steve's%20Page/Radio/RTTY/RTTY.html
or just page down from www.pituch.net

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Ken Alexander-2

Re: RTTY Problems

--- Steven Pituch <[hidden email]> wrote:

> As far as the other story goes....center them on
> 2210 Hz or whatever the
> RTTY center frequency is, then narrow them down to
> about 400 hz wide and
> then it will work fabulously.

Actually, I was just reading about that on Don
Wilhelm's website and will probably give that a try
tonight. I had my K2 built for me (arthritis in
hands) and recall now that I asked my builder (Don) to
set up the RTTY filters for PSK31, which was the
digital mode du jour at the time. Since then I've
become interested in RTTY and because I never got the
benefit of setting up my own filters I didn't realize
they were that configurable!

Don reminded me of all this several weeks ago but it
didn't register with me (arthritis of the brain?)

73 - Ken
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n8ewy

RE: RTTY Problems

In reply to this post by list1

If one centers their filters at 2210 Hz in RTTY mode for use in RTTY, then
is RTTY no longer the mode of choice for PSK31? Would you just use USB for
PSK31 and adjust your speech compression? Are RTTY and PSK31 both useable
with RTTY mode with filters centered around 2210 Hz?

Dohn N8EWY

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Steven Pituch
Sent: Saturday, March 17, 2007 5:29 PM
To: Elecraft
Subject: Re: [Elecraft] RTTY Problems

> (The crystal filters in RTTY mode are unusable for
> RTTY because they're centred on voice audio
> frequencies and not RTTY freqs. But that's another
> story.)
Hi Ken,
As far as the other story goes....center them on 2210 Hz or whatever the
RTTY center frequency is, then narrow them down to about 400 hz wide and
then it will work fabulously. My PK232 is centered on 2210 Hz so I aligned
the K2 filters to match. Now I can do PACTOR I with my K2.
See:
http://www.pituch.net/p/Steve's%20Page/Radio/RTTY/RTTY.html
or just page down from www.pituch.net

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Don Wilhelm-3

Re: RTTY Problems

Dohn,

You can always tune the PSK31 signal with the K2 VFO so the audio will
appear near 2210 Hz rather than the more traditional 1000 Hz. But many
RTTY software packages offer another alternative - adjust the RTTY tones
in the RTTY software.

I believe the better way is to tell the RTTY software to use lower tones
rather than the traditional 2210 Hz center. Of course that cannot be
done if one is using a hardware TU which does not implement a switch for
low tones. The traditional "Low Tones" for RTTY is 1275 mark and 1445
space - only the shift amount is critical. If you have your PSK31
filters set for 1000 Hz center and you can tell the RTTY software to use
915 Hz mark and 1085 space tones both RTTY and PSK31 signals can be
received with the narrow RTTY filters at a 1000 Hz center.

Remember that with all digital modes, the SSBC parameter should be set
to 1:1 for the lowest IMD and that RTTY FL1 must be set to OP1 (or OP2,
3, 4 or 5 - they are the same). Adjust the RTTY FL1 BFO to be the same
as those for SSB and all will be well on transmission.

73,
Don W3FPR

Dohn wrote:

> If one centers their filters at 2210 Hz in RTTY mode for use in RTTY, then
> is RTTY no longer the mode of choice for PSK31? Would you just use USB for
> PSK31 and adjust your speech compression? Are RTTY and PSK31 both useable
> with RTTY mode with filters centered around 2210 Hz?
>
> Dohn N8EWY
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Steven Pituch
> Sent: Saturday, March 17, 2007 5:29 PM
> To: Elecraft
> Subject: Re: [Elecraft] RTTY Problems
>
>> (The crystal filters in RTTY mode are unusable for
>> RTTY because they're centred on voice audio
>> frequencies and not RTTY freqs. But that's another
>> story.)
> Hi Ken,
> As far as the other story goes....center them on 2210 Hz or whatever the
> RTTY center frequency is, then narrow them down to about 400 hz wide and
> then it will work fabulously. My PK232 is centered on 2210 Hz so I aligned
> the K2 filters to match. Now I can do PACTOR I with my K2.
> See:
> http://www.pituch.net/p/Steve's%20Page/Radio/RTTY/RTTY.html
> or just page down from www.pituch.net
>
> _______________________________________________
> Elecraft mailing list
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> You must be a subscriber to post to the list.
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>
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>
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>

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Ken Alexander-2

Re: RTTY Problems

I'm all for anything that keeps me from fiddling with
the K2's filter setup! The thought of playing with
them makes me squeamish.

I just downloaded MMTTY and installed it on my
computer at the office and now see where I can change
the mark freq to 1275 Hz.

I know I should be embarassed for asking this, but:
If I'm generating tones at 1275 and 170 Hz shift and
somebody who's software is set up for 2125 & 170 Hz
tunes me in, he'll centre me in his display and decode
me fine. But if he transmits with his setup won't I
have to re-tune to decode him properly?

Ohhh...I know I'm going to regret this, but it's
Monday and I'm not firing on all cylinders yet!

73,

Ken Alexander, VE3HLS

--- Don Wilhelm <[hidden email]> wrote:

> Dohn,
>
> You can always tune the PSK31 signal with the K2 VFO
> so the audio will
> appear near 2210 Hz rather than the more traditional
> 1000 Hz. But many
> RTTY software packages offer another alternative -
> adjust the RTTY tones
> in the RTTY software.
>
> I believe the better way is to tell the RTTY
> software to use lower tones
> rather than the traditional 2210 Hz center. Of
> course that cannot be
> done if one is using a hardware TU which does not
> implement a switch for
> low tones. The traditional "Low Tones" for RTTY is
> 1275 mark and 1445
> space - only the shift amount is critical. If you
> have your PSK31
> filters set for 1000 Hz center and you can tell the
> RTTY software to use
> 915 Hz mark and 1085 space tones both RTTY and
> PSK31 signals can be
> received with the narrow RTTY filters at a 1000 Hz
> center.

Don Wilhelm-3

Re: RTTY Problems

Ken,

MMTTY allows you to select 915 for the mark frequency. If your K2 RTTY
filters are centered at 1000 Hz, that is a better choice than 1275 Hz.
Those you transmit to will not know the difference, and you can
communicate with anyone using the same shift (170 Hz). The software
compensates automatically.

73,
Don W3FPR

Ken Alexander wrote:

> I'm all for anything that keeps me from fiddling with
> the K2's filter setup! The thought of playing with
> them makes me squeamish.
>
> I just downloaded MMTTY and installed it on my
> computer at the office and now see where I can change
> the mark freq to 1275 Hz.
>
> I know I should be embarassed for asking this, but:
> If I'm generating tones at 1275 and 170 Hz shift and
> somebody who's software is set up for 2125 & 170 Hz
> tunes me in, he'll centre me in his display and decode
> me fine. But if he transmits with his setup won't I
> have to re-tune to decode him properly?
>
> Ohhh...I know I'm going to regret this, but it's
> Monday and I'm not firing on all cylinders yet!
>
> 73,
>
> Ken Alexander, VE3HLS
>
>
> --- Don Wilhelm <[hidden email]> wrote:
>
>> Dohn,
>>
>> You can always tune the PSK31 signal with the K2 VFO
>> so the audio will
>> appear near 2210 Hz rather than the more traditional
>> 1000 Hz. But many
>> RTTY software packages offer another alternative -
>> adjust the RTTY tones
>> in the RTTY software.
>>
>> I believe the better way is to tell the RTTY
>> software to use lower tones
>> rather than the traditional 2210 Hz center. Of
>> course that cannot be
>> done if one is using a hardware TU which does not
>> implement a switch for
>> low tones. The traditional "Low Tones" for RTTY is
>> 1275 mark and 1445
>> space - only the shift amount is critical. If you
>> have your PSK31
>> filters set for 1000 Hz center and you can tell the
>> RTTY software to use
>> 915 Hz mark and 1085 space tones both RTTY and
>> PSK31 signals can be
>> received with the narrow RTTY filters at a 1000 Hz
>> center.
>
>

Bill Coleman-2

Re: RTTY Problems

In reply to this post by n8ewy

On Mar 19, 2007, at 5:36 AM, Dohn wrote:

> If one centers their filters at 2210 Hz in RTTY mode for use in
> RTTY, then
> is RTTY no longer the mode of choice for PSK31? Would you just use
> USB for
> PSK31 and adjust your speech compression? Are RTTY and PSK31 both
> useable
> with RTTY mode with filters centered around 2210 Hz?

PSK31 can be used at any center frequency, so 2210 Hz won't be a
problem.

I use Cocoamodem and MMTTY for RTTY, and have adjusted them for
frequencies of 1415 and 1585 for Mark and Space, respectively. This
gives me a 1500 Hz center frequency, which is perfect for using the
DSP filters as well.

One problem with using 2210 Hz as a center frequency with the K2 is
that you may not have sufficient BFO range to center your filters for
both sidebands. You may have to modify the BFO to get greater range.
Having both sidebands centered is important. Even though you might
only use the LSB sideband for RTTY, remember the sidebands are
swapped on 15m and above due to the inversion.

Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901

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