[GreenKeys] ITTY question

Mon Nov 20 06:40:39 EST 2017

Sorry Nick, I forgot to mention the "European" tones of the Europe channel.

Now you can see how we Europeans felt all the years when we wanted to copy
ITTY...;-)
Before I got a Dovetron I modified the filters of a European RTTY TU to the
US tones.
Only VERY RARE (over here) Dovetrons were able to use both sets of tone
pairs
by easy adjustment.

73 Henning DF3OE

2017-11-20 4:01 GMT+01:00 Duncan Brown <duncanancy at earthlink.net>:

> Nick,
>
> The old RTTY standard used a 850 Hz shift, with standard M/S tones being
> 2125/2975 Hz.
>
> At some point in time, hams moved to a narrower shift of 170 Hz (military
> & commercial stayed with 850 Hz).  For 170 Hz shift, the mark tone was kept
> at 2125 and the space tone moved down to 2295 Hz. So on your board, NARROW
> is for 170 Hz, and CENTER is set for 2210Hz for ITTY US.
>
> For ITTY Europe, with 1275/1445 Hz tones, the center must be moved down to
> 1360 Hz.
>
> I found some info on Erick's board. It uses a standard phase-lock loop FSK
> detector chip, the 2211. I designed FSK  detectors with the 2211 chip 20-25
> years ago, but don't remember the details of it and can't tell from Eric's
> circuit how much range the CENTER control has. But you could try adjusting
> it and see if it will go down that low. Otherwise, you will need to make
> some component changes to copy ITTY Europe with it.
>
> As I remember, you can put a scope on pin 11 of the 2211 (which is the
> same point as the non-grounded lend of the "shift" resistors) and see the
> free-running frequency of the 2211. The CENTER control is adjusted to
> center this oscillator to your FSK signal.
>
> Good luck!
>
> Duncan
>
>
> On 19-Nov-17 20:32, Nick wrote:
>
>> Thanks Duncan
>>
>> The only two things I can change on Eric's board is a bridge, WIDE to
>> NARROW - it is bridged to NARROW at the moment and an adjustment screw,
>> named and marked on the board as CENTER.
>>
>> Nick  -  N0NCQ
>>
>>
>>
>>
>> Sent from my T-Mobile 4G LTE Device
>>
>>
>> -------- Original message --------
>> From: Duncan Brown <duncanancy at earthlink.net>
>> Date: 11/19/17 8:18 PM (GMT-05:00)
>> To: greenkeys at mailman.qth.net
>> Subject: Re: [GreenKeys] ITTY question
>>
>> Nick,
>>
>> ITTY Europe uses different tones than ITTY US - you should be able to
>> hear the difference.  Your AFSK converter/demodulator must be set up for
>> the proper tones. US tones are 2125/2295 Hz. Europe tones are 1275/1445
>> Hz. Go to RTTY.com and see
>>
>>
>>     Our RTTY over Internet Services
>>
>> for details.
>>
>> I'm not familiar with Eric's board. Does it have capability of switching
>> tones?
>>
>> have fun,
>>
>> Duncan
>> K2OEQ
>>
>>
>> On 19-Nov-17 19:32, Nick wrote:
>> > Hi gang,
>> >
>> > As I posted last week, I aquired a Siemens T37h in a beautiful wooden
>> > case (oak) and like to use that machine in the near future with
>> > iTelex. I got the machine running and the dialing until is repaired.
>> > Our iTelex-guru, Henning from Germany want me to do a final test
>> > before we go iTelex. He want me to copy ITTY EUROPE (50 baud, I guess)
>> > to see if absolute everything is in order with the T37 and the dialing
>> > until.
>> > Using Eric's demodulator board, I can copy ITTY news America on my
>> > 28KSR without a problem. Trying to copy ITTY EUROPE on the T37, the
>> > demodulator board doesn't do a thing, but I can hear the tone coming
>> > out of my PC and/or phone. It is not about what machine I am using,
>> > it's about that the demodulator is not kicking in. I know, on the
>> > demo-board is an adjustment screw for fine-tuning but I still can't
>> > get the board into action.
>> >
>> > Anybody with any info on my little challenge ???
>> >
>> > Nick  -  N0NCQ
>> >
>> >
>> >
>> > Sent from my T-Mobile 4G LTE Device
>> >
>> >
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>
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> 1998-to-2001 greenkeys archive: http://mailman.qth.net/archive
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>
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