[GreenKeys] Getting RTTY on the air

[Harold Hallikainen]

Thanks! I just recorded my signal off a websdr and then tried playing it
back into the TU-170. Didn't work! But receiving ITTY works. I checked the
transmit tone frequencies yesterday, and they looked good. I noticed that
they are not equal level, though. I'll look at the receive signal on a
scope and see if I can determine anything. The TU-170 did not even key the
loop on my signal.

Time for debug!

Harold


> Hi Harold,
>
> I think RTTY has been relegated to below 3600 now...sniff.....
>
> I believe there might still a RTTY group (RATTSNET) that meets in the
> evenings on the left coast here on 3598, LSB.  I quit listening to them
> when they changed to Olivia, so I dunno if they ever changed back.
>
> I'm sure some of the other gurus here on the list can fill you in on 
> your technical queries.
>
> Keep us updated!
>
> Richard kn7sfz in Orygun
>
> On 11/10/2020 6:59 PM, Harold Hallikainen wrote:
>> I've finished connecting my model 15 to the TU-170 to my radio (
>> https://w6iwi.org/SEA245/ ). I added an audio transformer and a reed
>> relay
>> to the TU-170 to drive the SEA245 tri-state audio bus. For testing, I'm
>> trying to get the RTTY decoder on a KiwiSDR ( http://rx.linkfanel.net/ )
>> to decode my signal. So, here are some questions.
>>
>> 1. I remember from MANY years ago, that LSMFT, or Low Space Makes Fine
>> Teletype. That, as I recall, is on RF, and it's reversed on AFSK. So,
>> the
>> TU-170 uses 2.125 kHz for mark and shifts up 170 Hz for space. That
>> indicates that the transceiver should be set for LSB to get the signal
>> right side up. Is this correct?
>>
>> 2. How is the transmit frequency normally specified? I can think of
>> several ways:
>>
>> a - Mark frequency
>> b - Center frequency (Mark frequency minus 135 Hz)
>> c - LSB "carrier frequency" (Mark frequency + 2.125 kHz
>>
>> Is one of these correct? If so, which one?
>>
>> 3. What are common frequencies on the HF bands for RTTY? From many years
>> ago, I think I remember 3.635 MHz for the mark frequency.
>>
>> 4. Anything special in the FSK settings on a KiwiSDR? Should the signal
>> be
>> inverted?
>>
>> THANKS!
>>
>> Harold
>>
>>
>>
>
>


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